Tag Archives: spray foam

A BONUS PBG for Friday May, 17th– Roof Insulation, Column Sizing, and a Moisture Issue. 

A BONUS PBG for Friday May, 17th– Roof Insulation, Column Sizing, and a Moisture Issue.

DEAR POLE BARN GURU: Hi Mike. I built a post and beam shop and am trying to figure out how to insulate the roof on the second floor. The bents are true sawn 6×6 on ten foot centers (building is 40 feet long and loft is 16 feet wide). I used true 4×4 purlins on top of the 6×6 bents. I put 5/8 OSB over that, underlayment, then metal on top. I put a ridge vent system in. Now I’m looking at insulating the roof from the inside. I really have no air passage ways as the purlins run horizontally. My thought was to use 3 inch owens corning foam leaving a one inch gap to the OSB. I read your piece on closed cell spray foam for unvented roofs but mine is already vented. Can you give me any advice please? Thank you. MATT in ATHOL

DEAR MATT: While your idea is noble, it is impossible to place foam boards to completely eliminate warm, moist air from getting through cracks and seams. Eventually moisture will be trapped against underside of your OSB and there the fun (not really) begins. You really need to block your ridge vent and use closed cell spray foam. This article is in regards to another person in a similar circumstance: https://www.hansenpolebuildings.com/2023/10/properly-insulating-between-roof-purlins/

 

DEAR POLE BARN GURU: I am planning to build a 48 x 48 Monitor style pole barn that I intend to use for RV storage in the middle and living space above the center section. Will 6″ x 6″ posts be adequate spaced 12 ft apart or should I use 8″ x 8″? TIMOTHY in MARION

DEAR TIMOTHY: Your building columns will be sized by our engineers based upon building heights and loads carried. I would suspect our 3 ply 2×6 glulaminated columns produced from 2400msr lumber (roughly 50% stronger in bending than any other readily available columns) will be likely to adequately carry imposed loads.

 

DEAR POLE BARN GURU: When vinyl backed fiberglass insulation is installed on a metal roof, and is enclosed with rib closures and the roof extends 2″ over the purlin, should water still be able to reach the fiberglass? If so, should the fiberglass be replaced? Would this be something the contractor would be responsible for? Thank you. MARY in GREENEVILLE

DEAR MARY: Properly installed water should not reach fiberglass. If you see any fiberglass at juncture of wall and roof steel, then it was not properly installed. During installation, last roughly four inches of fiberglass should be removed from vinyl, then vinyl folded back over fiberglass. Folded edge should be even with outside of beveled eave strut (eave girt/purlin). If improperly installed contractor should at the least remove roofing to allow fiberglass to dry, then reinstall correctly.

 

The Advantages of Spray Foam Insulation in Pole Barns

The Advantages of Spray Foam Insulation in Pole Barns

Spray foam insulation is an all-in-one solution that can effectively regulate temperature, reduce noise, and prevent moisture in your pole barn. Although all types of insulation minimize heat transfer, spray foam is the only material that can also seal against air leaks, potentially resulting in energy savings of up to 20%. Spray foam insulation is a liquid foam that hardens to form an air and vapor barrier made up of numerous tightly-packed air pockets or “cells” that are resistant to heat, sound, and moisture transfer. The foam also expands up to 30-60 times its original volume before it cures, so it can fill air gaps that traditional insulation materials can’t so easily reach. Spray foam insulation can therefore lower your heating and cooling bills and transform your pole barn into a comfortable and functional living space.

Temperature control

Spray foam insulation tends to regulate temperature better than other types of insulation. Closed-cell spray foam, in particular, has an impressive R-value of around 7 per inch (R-value is simply a measurement of how well a material reduces the flow of heat). And that’s a far higher R-value than most. Just take a look at other popular insulation materials in comparison — fiberglass batts provide around R-2.9 to 3.8 of insulation per inch, while stone wool batts provide R-3.3 to 4.2 per inch on average. The reason for closed-cell spray foam’s effectiveness is its unique structure: the interior cells within the foam remain fully closed and densely packed, which makes it harder for heat and air to flow through them. Alternatively, open-cell spray foam is still a fairly good insulator compared to other materials — providing roughly R-3.5 of insulation per inch — although it isn’t as powerful as closed-cell spray foam. As the cells in open-cell spray foam remain open and aren’t completely sealed, it’s a softer and less dense material. It therefore doesn’t regulate temperature quite as well as its closed-cell counterpart. In terms of price, spray foam insulation is a relatively expensive option, with closed-cell spray foam costing around $1-$1.50 per board foot (144 cubic inches) on average, whereas open-cell costs between $.045-$0.65 per board foot. However, the energy savings provided should offset that initial cost in the long-term.

Noise reduction

Spray foam insulation can also effectively reduce the amount of sound that gets in and out of your pole barn. The barrier created by the interior air pockets in both open- and closed-cell spray foam insulation successfully absorbs noise and minimizes sound transmission. Of course, without adequate insulation, the sound of wind, rain, and nearby traffic can sometimes be a problem inside pole barns due to their metal roofs. So, the noise reduction provided by spray foam insulation is an important benefit for most people, particularly if you need your pole barn to be a calm and peaceful living or working environment. Alternatively, if you use your pole barn for noisy activities (such as, music practice, woodwork, or metalwork) effective soundproofing with spray foam insulation is just as important to prevent noise pollution seeping through to the outside.

Moisture prevention

Closed-cell spray foam insulation also forms a strong vapor barrier that can keep moisture and mold out of your pole barn. Surprisingly, air leaks are actually the biggest reason moisture gets into buildings, accounting for “98% of all water vapor movement in building cavities”, the U.S. Department of Energy reveals. That said, it’s still important to prevent the problem of slow moisture diffusion, which is responsible for the remaining 2% of moisture problems. Closed-cell spray foam insulation can help here as it’s an effective standalone vapor retarder that simultaneously works to prevent the flow of moisture, air, and heat. Open-cell spray foam, on the other hand, is generally too light and airy to be able to form a strong vapor barrier. So, if you do opt for open-cell spray foam, you’ll also need to invest in additional vapor barrier coatings to adequately control moisture levels in your pole barn.

Spray foam insulation — and particularly closed-cell spray foam — is a great choice for your pole barn. It’s an all-in-one solution that effectively regulates temperature, reduces noise, and keeps out moisture to ensure your pole barn stays as comfortable, quiet, and energy-efficient as possible.

Challenges to Insulating an Existing Pole Building

Challenges to Insulating an Existing Pole Building

Reader TODD in STACY writes:

“Hello, I am looking to insulate and heat an existing 30x40x12 pole building that was built in the mid 2000’s. It does not have soffits or ridge vents. The way it is now it gets condensation on the inside quite often just with daily weather, I assume because of the lack of ventilation. I am planning on steel liner panel ceiling, poly vaper barrier and blown in fiberglass. But the problem is how do I achieve adequate ventilation without soffits? I am worried that once i get all the insulation in and still have condensation problems and end up with wet insulation. Also, last spring, as ALL the snow from last winter was melting the water was making it up and under the roof overlaps and was freezing and spreading them open and dripping inside! Would having it insulated have kept this from happening? I couldn’t help but think it was a good thing I didn’t have it insulated then or my insulation would of been soaked! But I thought maybe it wouldn’t of happened if it had been insulated, what are your thoughts on that? When it comes the wall insulation some say to wrap everything with a house wrap from the inside, insulate with fiberglass and then poly vaper barrier and then the steel liner panel. Others say the house wrap isn’t necessary just the inside poly. What do you recommend? Thank you for your help!”

It sounds like your building has several things going on, some of them easily fixable.

If your building does not have an under-slab vapor barrier – seal it. This is your top source of moisture inside of buildings. Think of concrete as a sponge rather than a solid (concrete being actually relatively porous). Pores in concrete (smaller than human hairs. so invisible to a naked eye) constitute 12 to 18% or more of a concrete slab!

Water coming through roof steel laps…this will normally only occur if steel has been overlapped incorrectly. Smaller, or partial, rib should go over top of larger full rib. This occurs all too often, even when supposedly professional builders are hired. If this is your case, it can be remedied – remove ridge caps (number them, so they get put back in same order they came off), then remove screws closest to laps. Pull up on edge of panel currently on top. While it is being held up, pull up on other panel edge, then put full lap edge down, overlapping it with partial lap. Use screws one size large diameter and 1/2″ greater in length to refasten steel panels.

vented-closure-stripWhile ridge cap is off, replace solid foam closure strips with vented ones. Use 1-1/4″ long #12 stitch (metal-to-metal) screws to reattach ridge caps.

Add gable vents for air intake, bottom edge of vents should be just above thickness of ceiling insulation you will be adding. You will need to add 144 square inches of NFVA (Net Free Ventilating Area) at each end.

I am guessing your roof steel has no means of controlling condensation currently. Your easiest solve, at this point, is to have two inches of closed cell spray foam applied directly to underside of roof steel. Otherwise, you could remove entire roof and install a thermal break. Some possibilities would be reflective radiant barrier (with seams taped), metal building insulation (with seams overlapped and stapled together), or solid sheathing (such as plywood or OSB) with 30# felt applied over top.

If you can obtain it, consider blowing in granulated rockwool, rather than fiberglass, as it is not affected by moisture.

Walls – while housewrap would have been nice, rather than pulling off all wall steel, I would use rockwool batts to entirely fill cavity, well-sealed interior vapor barrier, then your steel liner panels.

Vapor Barriers, Post Longevity, and Spray Foam

This Wednesday the Pole Barn Guru answers reader questions about the need for a vapor barrier, the longevity of properly treated posts, and the better spray foam between open and closed cell.

DEAR POLE BARN GURU: Hello Sir, hoping you can help answer a question I cannot get a straight answer on. Currently building a 30x40x14 building and have the walls and roof house wrapped with Kelly Clark Block It. Steel is going on the building now. I just ordered steel for interior ceiling and trying to figure out if I should add a vapor barrier to bottom of truss first. Thoughts? MATT in ILLINOIS

DEAR MATT: Block it is wrong product for under roof steel. It allows moisture to pass through and be trapped between it and roof steel. As long as you do not blow in cellulose, you should not need a ceiling vapor barrier.

 

DEAR POLE BARN GURU: I bought a pole barn that has been retrofitted to a house. The posts are in ground. I’m worried about future resell and longevity of the post. Also, I’m in a cold climate and wonder if a proper footing would help with heating. Is there any good way to retrofit from in ground post to stem wall or something similar. I’m sure it’s all possible if money was not an issue. I’m looking for an economical solution. Thanks!! NICK in WEST LIBERTY

DEAR NICK: Properly pressure preservative treated columns (UC-4B) should outlast anyone alive on our planet today, especially in climates (such as yours) not prone to termite infestations. As for improving ability to heat – dig a trench around outside of building at least two feet wide and two feet deep. Invest in 2′ x 8′ (or 4′ x 8′ to be cut in half lengthwise), R-10 EPS insulation boards. Attach vertically to exterior side of pressure treated splash plank with top of insulation even with top of interior concrete slab. Run another 2′ horizontally out away from building at bottom of vertical. Any portion of vertical insulation above backfill will need to be protected from UV rays. This should keep your slab from getting so cold, as well as help to avoid frost heave. If you are in an area prone to burrowing rodents, you should further protect insulation https://www.hansenpolebuildings.com/2021/03/rascally-rodents/

 

DEAR POLE BARN GURU: I am trying to decide whether to go with open cell or closed cell spray foam on my bare metal pole barn walls. I will be enclosing the walls with some material, most likely plywood. What are your opinions regarding the pros/cons (is one or the other worse for corrosion, condensation, other pertinent factors, etc.) of the two foam approaches? Thanks so much! TERRI in CHESTER

DEAR TERRI: Open cell spray foam allows moisture to pass through and condense against steel cladding. I would not recommend it being used unless a two-inch thick layer of closed cell was first applied, then add open cell for extra R value (and to deaden sound).

Sourcing Treated Columns, Truss Bracing, and Insulating a Roof

This Wednesday the Pole Barn Guru answers reader questions about sourcing 4pc of 4x6x18′ treated columns, truss bracing in a custom cabin, and insulating a roof on a metal pole barn.

DEAR POLE BARN GURU: Looking for 4pcs 4x6x18 treated ground contact. JERRY in COATESVILLE

DEAR JERRY: This one is going to be tough. Very few lumber dealers inventory pressure preservative treated 4×6 in lengths over 16′. other than in Pacific Northwest states. For a lumberyard to bring them in, they will usually be forced to have to purchase an entire unit – not very practical for them or for you. Your solution is most likely to source 6x6x18′ as they should be in stock.

 

DEAR POLE BARN GURU: Trying to figure if I need more braces or not. 18 ft cathedral with king post truss. No supporting interior walls both garage below and great room are open floor plan. So I used 5/8 plywood both sides of garage walls to help with sheer wall and racking bolted everything down and now got tongue and groove on interior upstairs so should be ok . Just would like something more but maybe this enough just as it is. I got horizontal Xs up in rafter ties. I also have collar ties in peak. But other than that everything seems good I used double 2×10 for each truss from sill to peak then double 2×6 as rafter ties. BUCK in DERBY LINE

DEAR BUCK: Every bottom chord should probably be braced at centerline, not just some of them. Short of this, I couldn’t venture a guess without reviewing an entire set of structural plans.

 

DEAR POLE BARN GURU: After reading some opinions on some forums I am getting ready to insulate the roof of my metal pole barn. Paper backed fiberglass insulation will not stop condensation without putting plastic sheeting over top of it. How do you feel about this method? Insulation against the underside of the metal roof with plastic over the insulation. DAVE DEAR

DAVE: This should answer some of your questions https://www.hansenpolebuildings.com/2023/10/properly-insulating-between-roof-purlins/

 

Ballpark Figures, Blueprint Costs, and Condensation Drip

This Wednesday the Pole Barn Guru answers reader questions about ballpark figures to estimate costs of a barndominium, the costs for blueprints for a 40x60x20 building, and what the best way to stop condensation drip on a post frame building would be.

DEAR POLE BARN GURU: I’ve got a very general question, hope you can help. Is there a very ballpark figure for estimating a barndominium? As in square foot to dollars. My current house is 2500 sqtf. on two acres. I’d like less house on larger property. Currently negotiating with a friend for 7 acres. Need a ballpark figure on construction in order to decide if it’s just a pipe dream. Thanks JIM in MONEE

DEAR JIM: Thank you for reaching out to me Jim, message me any time with questions. Fully engineered post frame, modest tastes, totally DIY, move in ready, budget roughly $70-80 per sft of floor space for living areas, $35 for all others. Does not include land, site prep, utilities, permits. If you hire a General Contractor to do everything, expect 2-3x as much.

 

DEAR POLE BARN GURU: I’m looking to some blueprints for a 40x60x20 pole barn it will have 2 10×12 doors on the gable end wall. I want a 2 foot over hang. I want to sheet the roof with 5/8 cdx and walls with 1/2cdx. How much would the blueprints cost? MICHAEL in COOS BAY

DEAR MICHAEL: Thank you for reaching out to me Michael. Our engineers will only seal plans when we provide the materials, as it is the only way they can guarantee materials they specify will actually arrive onsite. Please send your specifics to Caleb@HansenPoleBuildings.com along with your site address and best contact number. You will find we are very competitive and have provided hundreds of fully engineered post frame buildings to our clients in Oregon.

 

DEAR POLE BARN GURU: Hello, I asked an insulation question on social media and it quickly turned into a debate among other members. In your opinion is there any way to stop the condensation drip on a porch we would like to cover with T/G, box in with soffits? This is a new post frame building with an offset porch. Initially we planned to leave framing exposed but due to birds and wanting a more finished look we would like to put a ceiling in place. Thank you. MEL in ISLAMORADA

DEAR MEL: As it is already existing, your quickest and easiest is to do 2″ of closed cell spray foam directly to roof steel underside.

 

 

Open Cell Spray Foam to Roof Steel – When Insulation is Done Wrong

Open Cell Spray Foam to Roof Steel – When Insulation is Done Wrong

Reader JOSH in FARMINGTON writes:

“I recently had a pole barn built and after doing a lot of research, went with 5″ of open cell under the roof and on the gables. I did not have any kind of vapor barrier, as I was worried the weight of the foam would cause it to sag and create air gaps where moisture could accumulate. I checked with the metal supplier to confirm it would not cause warranty issues and they said it would not. I am somewhat 2nd guessing the open cell, but I did it because I want to make sure I see any leaks that might occur from the exposed fasteners. I have not insulated the walls yet as I wanted to get all the electrical done. My plan was I would spray low expansion foam at the top and bottom of the metal sheets because right now there are no foam seals so you can actually see daylight even with the metal rat guards. To seal these up I want to use Great Stuff Pond & Stone foam. It’s black to match the trim in case it pushes out, it’s waterproof, it’s low expansion, and it’s UV rated. Then I was going to put 1.5″ foam board between the purlins, sliding it behind the posts. Following up with covering both with another sheet of 2″ foam board and use tape at the seams and some more foam at the posts. My thought is this would create a good vapor barrier, but I’m second guessing that now. For one reason, I don’t know how I’d seal things up above the header. They used a double 2×10 on each side of the post to act as the header. I do not plan to put a ceiling up and I will have a split system with a gas furnace installed soon to keep the space tempered between 60-80. I’ll heat it up or cool it down as needed when I’m using it. Do you see any issues with this setup? I’m a little worried about not having a vapor barrier on the roof. In Arkansas, we have all seasons, but it stays pretty muggy.”

My first concern is your open cell spray foam against roof steel. You have an application here I would never recommend. Open cell spray foam allows moisture to pass through, so you are going to end up with moisture condensing on underside of roof steel. I do not have a solution at hand for this – perhaps whoever installed your spray foam has some ideas.

As you propose to insulate your walls, you are creating a vapor barrier – meaning your walls will ‘dry to inside’ – adding even more moisture to potentially cause a problem in your open cell roof insulation. I would remove steel siding from a wall at a time, then install a well-sealed housewrap. Fill insulation cavity with rockwool batts (as it is not affected by moisture), with an interior vapor barrier. Walls will now dry to outside.

Chances are you are going to need to mechanically dehumidify your building in order to minimize condensation from moisture hitting roof steel.

Greyed Lumber, Insulation, and Flat Purlins over Trusses

This week the Pole Barn Guru answers reader questions about cleaning up rough cut lumber that has greyed from exposure to the elements, advice on house wrap and insulation, and the ability of flat purlins over trusses to carry a load in Kentucky.

DEAR POLE BARN GURU: My barn project has been a long drawn out process. The project stalled for 6 months but has picked back up again. I’m using rough cut lumber. Unfortunately, the wood has a grey color to it (probably from dirt, mold or algae on the surface).

What’s the best way to clean it to make it look fresh/revived again? Any products that you recommend?

Thank you again for all your help and advice. JAMES in MILTON

DEAR JAMES: Clean with sodium percarbonate or hydrogen peroxide, then apply oxalic or citralic adid (second step restores wood to its natural pH and neutralizes sodium percarbonate cleaner).

 

DEAR POLE BARN GURU: I added a lean-to to my 60×90 pole barn. The builder put house wrap around exterior walls. When the tin guys put up the metal they put bubble wrap over the house wrap then the metal. I spray foamed with closed cell inside 2 inches. The interior will be knotty pine so do I need to put another barrier before the wood? Also on the roof they put the bubble wrap under the steel I will have blow in on top of the knotty pine. I plan on putting plastic sheathing before the knotty pine. Is this the correct way of doing or should we change something? SCOTT in KOUTS

DEAR SCOTT: It was bad enough when your tin guys put bubble wrap over your housewrap. Compounding your having spent your hard earned money on both, is closed cell spray foam should have been applied directly to inside of steel siding. Water under a bridge at this point. You should fill balance of wall cavity with unfaced rock wool and no interior vapor barrier. Wall will now dry to inside (meaning you may have to mechanically dehumidify). You did not say if your added lean to has an attic space or not. If your intent is to insulate with plane of roof (purlins) here is some guidance: https://www.hansenpolebuildings.com/2023/10/properly-insulating-between-roof-purlins/

If you are insulating above a lower ceiling height (as you say blow in – I will guess this is your case), in your Climate Zone 5A a vapor retarder should be on warm in winter side of insulation (not a vapor barrier, like plastic sheeting). A vapor retarder could be as simple as kraft facing from batt insulation, or latex ceiling paint. Make sure to adequately vent any non-conditioned attic space.

 

DEAR POLE BARN GURU: I love reading your posts. I’ve learned much about your ideas and it’s changing the way I think. Thank you. Iowa and SD have different wind and snow loads than central KY. I routinely see farmers building barns with 2×4 purlins laid flat on trusses spaced every 8 feet. Your designs call for 12 spacing, which I love, and 2×6 purlins on edge in joist hangers. Would 2×4 purlins in joist hangers work in central KY?

CHRISTOPHER in RICHMOND

Welcome to Kentucky road sign at the state borderDEAR CHRISTOPHER: Thank you for your kind words.

We have provided fully engineered post frame buildings in places with no snow, to places where snow load is over 400 pounds per square foot – so we have pretty much seen it all!

Those farmers laying 2×4 purlins flat (wide face to sky) spanning eight feet are risking not only their buildings, but their lives. I am amazed they can even apply roof steel to them without failures.

For 12′ spans, without snow, purlins on edge, 2×4 2400 msr roof purlins 24 inches on center would carry loads, however would overly deflect. You could probably use 2×4 #2 Southern Pine at 12 inches on center, however 2×6 #2 at twice spacing would be more economical both in materials and labor.

Read more about msr lumber here: https://www.hansenpolebuildings.com/2012/12/machine-graded-lumber/

Plastic Vapor Barrier, PermaColumn, and a Fire Resistant Barrier

This Wednesday the Pole Barn Guru answers reader questions about use of 6 mil plastic vapor barrier in Michigan, if Hansen provides the option of a precast concrete pier to keep columns out of the ground, build heights, and “if anything needed between interior PVC panels, closed cell spray foam and the exterior metal siding.”

DEAR POLE BARN GURU: I have a pole barn that I am planning on insulating. The trusses are 2 foot on center and it has a shingled roof, the outside of the pole barn is steel. I live in Michigan and I was wondering if it is a good idea to put 6 mil plastic on the bottom of trusses before I hang steel on the ceiling. I will be blowing in insulation up there later. KAL in HUDSONVILLE

DEAR KAL: You are in Climate Zone 5A, so a ceiling vapor barrier is not required by Code. Building scientist and founding principal of Building Science Corporation Joe Lstiburek states, “Plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days.” (More on degree days here: https://www.hansenpolebuildings.com/2022/11/what-is-degree-day/).

I would only recommend you installing a vapor barrier above your steel ceiling if you were to be considering blowing in cellulose insulation. Why cellulose? https://www.hansenpolebuildings.com/2022/10/cellulose-post-frame-attic-insulation/

 

DEAR POLE BARN GURU: Do you deal with post frame designs that: 1) use the precast column to keep wood out of the ground? 2) Deal with designs that are 20′ eave height to accommodate 2 story interiors. JONATHAN in ZANESVILLE

DEAR JONATHAN: We have had several clients provide their own pre-cast Permacolumns and they can be incorporated into our engineered designs. There is, however, a less costly option to explore: https://www.hansenpolebuildings.com/2018/04/perma-column-price-advantage/

We can engineer and provide up to 40 foot tall walls and three stories without needing fire suppression sprinklers, so 20 feet eave heights are not a problem.

 

DEAR POLE BARN GURU: Hello, my question, which I can’t seem to find a straight answer anywhere online. Is anything needed between interior PVC panels, closed cell spray foam and the exterior metal siding? The pole barn is located in southern Indiana. It’s used as a shop and being heated occasionally with a wood stove. BENJAMIN in INDIANA

DEAR BENJAMIN: As your PVC and closed cell spray foam are both flammable, I would use an intumescent fire proof paint on interior face of closed cell spray foam, then fill balance of wall cavity (if any) with rockwool batts. As an alternative to intumescent paint, you could place sheetrock between wall framing and PVC panels (panels will lay much smoother).

Housewrap, Roof Insulation, and Ceiling Fasteners

This Wednesday the Pole Barn Guru answers reader questions about a home owner asking builder to install housewrap on the roof, the best solution to insulate underside of roof, and what the best fastener for screwing steel to ceiling or roof trusses would be.

DEAR POLE BARN GURU: Pole Barn Guru, thank you for your knowledge. I have a customer wanting house wrap around the exterior of a 30×40 pole barn. Is house wrap to be installed in between purlins and roof steel or will I need a radiant barrier to prevent condensation? Home owner says house wrap on the roof as well but I’m not sure if that’s the route he really wants to go. House wrap on side walls in between girts and side steel is also the best route correct?

Thank you for your kind words, they are much appreciated. Provided your client will not be doing closed cell spray foam on walls, use house wrap between girts and wall steel. For his roof, housewrap is totally incorrect, as it allows moisture to pass through and become trapped between wrap and roof steel – potentially causing premature degradation. If your client is not closed cell spray foaming directly to roof steel, then order your roof metal with an Integral Condensation Control factory applied (Dripstop, Condenstop or similar) https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/. If roof steel has already been ordered (again assuming no closed cell spray foam being applied), then you do need some sort of a thermal break – such as a well-sealed radiant barrier.

 

DEAR POLE BARN GURU: Hi Mike, I built a 32’X40’X12′ pole building, (Shop) I used 1 1/2″ foam board on the inside walls, (on the inside of the girts) I can’t decide how I should insulate the underside of the roof. I have had a couple Spray Foam guy’s quote it , that’s pricy. Of course, the best R Value etc. at the most reasonable price is what I am looking for. In some of your post you have mentioned Rockwool that has gotten my attention. I see they make it up to R30. One thing that sticks in my mind is, my builder suggested not to use an insulation that will give insects a place to live. What would be your suggestion for underside of Roof insulation. Thank you. JIM in SPRING HILL

DEAR JIM: If your building has no current provision for controlling condensation on underside of roof steel, then two inches of closed cell spray foam applied directly to steel is your best insulation option. If you desire a greater R value, you can go thicker, or add open cell.

 

DEAR POLE BARN GURU: What screw is best for installing metal panels on the ceiling to wood trusses. MICHAEL in WENTZVILLE

DEAR MICHAEL: Most people are using #9 or #10 diameter 1″ screws. If you have ceiling framing 24 inches on center and want to utilize strength of ceiling liner panels to help transfer wind shear loads, then 1-1/2″ long diaphragm screws would be a better design solution.

Help! Help! PEMB Insulation/Ventilation

Help! Help! PEMB Insulation/Ventilation

Reader JD in ANDERSON writes:

“Dear Guru, I am finally ready to build my dream shop, rec space. Slab is poured. Will be 30x50x16 with (2) insulated panel 12×14 overhead doors in one of the 30ft ends. My question is about ventilation / insulation. To meet my budget, I chose a cold formed steel framed building with vertical 24 gauge steel roof & siding. I want the building to be “livable” & plan to install (2) mini split heat pumps for heating & cooling. I’m in southern SC so no real extreme temps. The building co wants to insulate with Prodex sandwiched between the siding & frame. There is no finished ceiling or attic space & there is a ridge vent from end to end. When asked about how to keep heat in during the winter due to the ridge vent, they tell me “that’s not something we worry about”. Not sure what that means but I assume heat rises & will vent out the ridge making it impossible to heat. Down the rabbit hole I went. First thing I found was everyone bashing Prodex. Ok, I figure the majority of steel buildings have been insulated with faced fiberglass batt since the beginning of time, I’ll do that. Then I read about moisture & mold caused by the batt. Ok, spray foam then, perfect! Then I’m told it voids the building warranty. My head hurts! I have just about decided to spray foam anyway with 2in of close cell on the walls & the roof. But what about ventilation? The spray foam folks say that with their product there is no need to ventilation in the building at all. They say no need for the ridge vent & the closed cell will be sprayed right over it to seal it off. If I don’t use the Prodex, the building co says there will be no heat transfer break between the siding & framing. Siding will be screwed straight to metal frames. There will also be no radiant reflective barrier or vapor barrier. The spray foam place says I don’t need either. They say the miraculous closed cell foam will handle it all. Basically they are telling me that the inside of my building will be a huge styrofoam beer cooler & will need no ventilation to control moisture & there will be no heat transfer at all. This is a HUGE investment & I can only do it once. It has to be right the first time. Please help!!!! Thanks so very much!!!”

There is sadly so much bad information available.

Prodex (or any other reflective radiant barrier) is not insulation. If properly sealed, it can be an effective vapor barrier. If you use it and vent ridge, then you are correct – out ridge goes your heat.

Fiberglass is not a cause of mold and mildew, it is a symptom of a building without adequate methods of removing excess moisture.

Closed cell spray foam – ask to see a written warranty copy showing building or even steel cladding with closed cell spray foam applied will void it. Chances are very small one exists.

What would I do?

Closed cell spray foam at least two inches thick sprayed directly on inside of steel roofing and siding. No ridge vent. Have a qualified HVAC provider design a system to mechanically remove excess humidity. You will need to fire protect inside face of closed cell spray foam. This might be an option https://www.hansenpolebuildings.com/2019/08/fire-rated-spray-foam-insulation/. Intumescent paint may also be a possibility. If you want higher than R-14, you could go with thicker closed cell, add open cell to inside face of closed cell, or add unfaced batts (my preference would be rockwool)

Spray Foam Insulation on Interior Surfaces of Metal Panels

Spray Foam Insulation on Interior Surfaces of Metal Panels

Information excerpted from MBCI.com

When it comes to insulating a building envelope, there are various methods that can be used depending on the building’s purpose and the required level of insulation. However, combining metal roof and wall panels with spray polyurethane foam insulation (SPF) is widely considered one of the most effective ways to achieve secure, strong, and long-lasting insulation. Utilizing this method of insulation offers numerous benefits including the sealing of panel joints, creating a vapor barrier, providing thermal insulation, and producing air barriers.

One of the most notable advantages of utilizing SPF insulation is that it can be used to fill spaces in the panel assemblies and function as a key component of an air barrier system, effectively reducing air leakage. However, there are a few design parameters to be mindful of when considering the use of SPF insulation for metal roof or wall panels. The Spray Polyurethane Foam Alliance (SPFA) has conducted research on the installation of SPF on steel panels and has suggested the following best practices for applying SPF to the interior surface of metal panels:

Closed-cell foam is recommended due to its water-resistant capabilities.

SPF is a recognized insulation material to be used below and in contact with through-fastened metal roof assemblies.

The surface of the metal panel being sprayed should be free from moisture, lubricants, dirt, or other contamination.

The technique used to apply the SPF can affect the performance and appearance of the foamed panels.

Using a release fabric membrane between foam and a metal panel in a wall assembly is not recommended due to the potential of creating voids between the SPF and the wall panel.

There is potential for stress-induced deformation (or “oil canning”) on 29 gauge or thinner material. (This can be minimized by following the foam manufacturers’ recommended application technique.)

Always follow national and local code requirements for fire protection. Exposed SPF may require an additional thermal barrier or other means for fire protection.

Consider using an SPF contractor accredited by SPFA’s Professional Certification Program (1) (compliant with ISO 17024) to provide high-quality and safe installation of SPF insulation.

It is important that a certified foam spray technician applies SPF to the required insulation thickness to achieve the optimum insulation density, adhesion, and thickness. The recommended application method when applying the foam is to use the controlled thickness spray technique, commonly known as the “picture frame” technique. SPFA describes this technique as if someone were following through the motion of picture framing, in which the applicator surrounds the interior perimeter of the wall framing stud and allows the foam to rise along the stud. This technique can also help to prevent SPF from getting between girts and architectural metal wall panels which could cause metal deformation.

The thickness of the initial pass fillet during picture framing should be at least 0.5 inch and should not exceed the maximum pass thickness recommended by the foam manufacturer. The minimum thickness of the initial pass is specified to provide enough material to activate the blowing agent and initiate the cure. After picture framing the perimeter of the area, the applicator fills in the center of the cavity using the maximum thickness recommended by the foam manufacturer. Maximum pass thickness varies by foam formulation and is listed in the technical data for each SPF product. Excessive pass thickness can result in inferior quality due to the increase in foam temperature during curing. For most closed-cell SPF, the maximum pass thickness is 1.5 to 2 inches. It is important for applicators of closed-cell SPF to follow manufacturers’ installation instructions on pass thickness limits and proper cooling times between subsequent passes made if they wish to develop the desired total thickness of the insulation.

Installers are trained to check the substrate surface for moisture, dirt, oils, rust, or other conditions that can interfere with proper foam adhesion. It is also important to clean the surface of these contaminants prior to spraying the insulation. If there is uncertainty surrounding the amount of adhesion needed for a metal surface, this can be determined onsite using a pull-tester in accordance with ASTM (American Society for Testing and Materials) D 4541 (Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers).

When the time comes to change an outdated or damaged panel, many SPF contractors use a release material such as building wrap or fabric to allow for a seamless and pain-free swap out. However, it is important to keep in mind that the use of a release material poses the potential of creating air gaps between the back of the SPF foam and the metal panel. These gaps could allow condensation to accumulate between the SPF and the panel and framing members.

Closed-cell Spray Polyurethane Foam is a viable insulation material for the interior surfaces of steel and aluminum metal wall panels. This foam application can be highly nuanced, and there is a possibility of deformation, distortion, or oil canning if the application of the SPF is done poorly

What Bubble Insulation Brand do you Recommend, if Any?

What Bubble Insulation Brand do you Recommend?

Reader ERICA in WEST COLUMBIA writes: “Is there a specific bubble insulation brand you recommend? We will be using this as our vapor barrier in the roof. I’ve seen posts about this type of insulation disintegrating, so I’m wondering if the claims are exaggerated or if in fact it could be a certain brand. Also we are wanting to have cathedral ceilings throughout our building. Our roof is made with metal trusses and wood purlins. We are using bubble insulation and some type of batt insulation. What is the best method to vent if we are not going to have an attic space?”

To use batt insulation between roof purlins requires a minimum of an inch of continuous air flow between roof deck (roof steel) and insulation. To achieve this, you would need to add framing (such as 2×4 placed flatwise) running from eaves to ridge, then another layer running opposite direction. You could then use a reflective radiant barrier (bubble wrap) between overlays and batt insulation between purlins, up to depth of purlins. This requires vented eaves and a ridge vent.

Instead, look at spraying two inches of closed cell spray foam directly to underside of roof steel (between purlins), then fill balance of purlin cavity with unfaced rockwool batts. This will get you a higher R value and save on material and labor for a lot of 2×4. You should not vent either eaves or ridge in this case.

As for bubble ‘insulation’ – it is not insulation, at best (when completely sealed) it is an effective vapor barrier. There have been real problems with white vinyl facing of reflective radiant barriers flaking off over time. We had this same problem with our first supplier (and, of course, they went bankrupt before problems showed up). After selling millions of square feet, we stopped offering any reflective radiant barriers to our clients.

Read more about reflective radiant barriers here: https://www.hansenpolebuildings.com/2014/04/reflective-insulation-wars/

Converting an Unfinished Wood Frame Steel Building

Converting an Unfinished Wood Frame Steel Building

Reader GEOFF in WILLISTON writes:

Mike, I think I came across a response on the internet of yours to a question about installing liner panels on the bottom chord of trusses and blowing insulation over the top. If memory serves me the question included the position of the vapor barrier on the liner side of the insulation.  You had also recommended 2″ of spray foam on the underside of the roof panels to control condensation. My customer is converting an unfinished wood framed metal building into an equipment wash bay. I’m recommending spray foam on walls with liner panels over and liner panels affixed to the bottom cord of the trusses above. Do you think a vapor barrier on the bottom chords before liner panels, then blown insulation and spray foam on the underside of roof panels, and some power venting of the “attic” space should be about as effective as can reasonably be expected? (Trusses at 6′ O.C. with some supported added between.) “

I tend to agree with building scientist and founding principal of Building Science Corporation Joe Lstiburek.

Joe stated, “Plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days.”

Read more on degree days here: https://www.hansenpolebuildings.com/2022/11/what-is-degree-day/

What is Degree Day? – Hansen Buildings

According to Joe Lstiburek, “Plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days.”

www.hansenpolebuildings.com

In our climate, I would only install a ceiling vapor barrier above steel liner panels if I was intending to use blown cellulose for attic insulation. This is due to chemicals added to cellulose to prevent combustion tend to degrade steel if moisture is present. I would much rather see blown in granulated rockwool (my first choice) or fiberglass.

Attic ventilation is going to be critical here and is best resolved with adequate eave and ridge vents, rather than trying to be reliant upon an exhaust fan or fans.

Doggie Day Care

Hi Guru, I Need Your Guidance

Reader CHRISTINA in MILFORD writes:

“Hi guru, I need your guidance. I am looking to build a 30x135x14 commercial building for dog daycare. I have no experience in building/ordering a pole barn and want to get it right.

Bullet points: I need 4000 sq ft. broken down: 3000 for daycare with 1 garage, 1000 with garage for any type of renter to take an income. Side note: I did 14 feet for a car lift if renter was a mechanic. Question: is 30 wide the most cost effective width for my usage?

Insulation-would like it to be energy efficient: what is best to keep heat in? Spray foam or fiberglass. What rating/factors? Ceiling-thinking 10 ft ceiling to keep heat low. What’s best material for ceiling? Acoustical tiles 2×2, metal, or sheetrock. Will I need a vapor barrier? Spray foam, loose fiberglass bail or fiberglass rolls?

Gauge: what is the best gauge for my usage? Ventilation: what are soffit vents and do I need them in my structure in summer to release hot air from the ceiling. What is the best way to keep the structure cool/warm? Windows: would you recommend a window(s) high up that can be opened to have cross ventilation or a way to get rid of hot air? Concrete-radiant floor (hot water with pex) enough to keep dogs and employees warm or do I need a HVAC system too. Please include anything else I might have missed. Gotta get it right the 1st time. Thank you!!!”

Thank you for reaching out to me.

In answer to your questions:

Buildings closer to square are more cost effective than long, narrow ones. They reduce surface area of walls – so less expense in siding and interior finishes, as well as lower utility costs. Long, narrow buildings also put greater wind shear loads on roofs at each end as well as endwalls. This can result in a need to add structural sheathing to portions, adding to your investment further.

If you are considering your renter may be in automotive repair, you may want to consider a 40′ width, as it would allow for two standard vehicles to be parked inside end-to-end.

Pike County is in Climate Zone 5A

Under 2021’s IECC (International Energy Conservation Code) for commercial buildings Ceilings should be R-49, Walls R-20 plus R-3.8 continuous, slab R-15 three foot down at perimeter and R-5 under slab itself.

For roof system – order 29 gauge roof steel (https://www.hansenpolebuildings.com/2012/01/steel-thickness/) with an Integral condensation control factory applied (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/), vent eaves and ridge in correct proportions (https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/), raised heel trusses  (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/), blow in R-49 of granulated rockwool (personally, I would do R-60).

Walls – commercial bookshelf wall girts (https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/), Weather Resistant Barrier between framing and wall steel (think Tyvek or similar), unfaced Rockwool Batts with well-sealed 1″ Rockwool Comfortboard 80 applied to interior of wall framing.

Slab – at edges 4″ Rockwool Comfortboard 80 applied to inside face of splash plank and down vertically 3′. 1-1/4″ Rockwool Comfortboard 80 under slab.

I would use 5/8″ Type X drywall for the ceiling, without a vapor barrier. You will need to fire separate between rental shop and doggie day care. For the sake of making certain almost any occupancy will be allowed, plan on two layers of 5/8″ Type X on each side of the wall with no penetrations between.

Besides your radiant floor heat, I would also plan on an HVAC system capable of controlling humidity.

Most jurisdictions require a pre-application conference for commercial buildings, you will want to verify if this is available (https://www.hansenpolebuildings.com/2013/01/pre-application-conference/).

Ceiling Insulation, Truss Spacing, and Custom Multi-use Barn

This Wednesday the Pole Barn Guru answers reader questions about best way to insulate a vaulted ceiling, truss spacing, and the possibility of adding a small living quarter to a horse barn.

DEAR POLE BARN GURU: With a vaulted ceiling, how do you insulate it if you plan to spray the tin roof with closed cell foam. Was planning on bat insulation on the lower cords of the trusses if needed. what about venting if you spray foam the tin roof? CHRIS in DORCHESTER

DEAR CHRIS: Saline County is located in Climate Zone 5A. As such conditioned buildings require R 60 attic insulation.

You can either:

Have a conditioned attic space – using closed cell spray foam at least two inches thick against underside of roof deck, then adding open cell spray foam or unfaced rock wool batts to get to required R value. This assembly will not be ventilated.

Or

An unconditioned attic. If you have no other method of condensation control, then again place two inches of closed cell spray foam directly to roof steel interior. Vent eaves and ridge, then blow in R 60 of fiberglass across attic. Insulation baffles will need to be placed at eaves to allow for at least an inch of unobstructed air flow above blown in insulation.

 

DEAR POLE BARN GURU: Hello Mike, I have a question regarding a post frame building I would like to build. the size is 40′ x 32′ x 16′ with 6/12 roof pitch. I am planning to use trusses at 2′ foot centers. my question is regarding using 3 tab composition shingles for my roof covering (I have a HOA that will not allow metal roofs), what special considerations might I need to take with respect to where the trusses attach to the top of the post frame wall? the posts will be at 8′ centers and standard girts installed. I was thinking that perhaps increasing the dimensions of the top girt would be necessary. I would appreciate your thoughts on my intentions. I have enjoyed your YouTube videos as well. Sincerely MARK in CODY

Ask The Pole Barn GuruDEAR MARK: Thank you for your kind words about our YouTube videos. https://www.youtube.com/user/HansenBuildings
Personally, I would place double trusses to bear directly upon columns spaced every 10 to 12 feet with purlins on edge, joist hung between truss top chords. This design results in fewest number of holes needing to be dug, as well as fewest pieces of materials to have to install. It also allows for wider door openings.

Doing as you propose, truss carriers (headers between columns to support trusses) would need to be adequately sized by your building’s engineer in order to carry imposed loads without failure or undue deflection.

 

About Hansen BuildingsDEAR POLE BARN GURU: Do you all have barns with living quarters? Not looking for a barndominium, per se, but a restroom with a shower and a living room in addition to 4 stalls and a tack room. we plan on staying there at first while we build the main house on the property, then use for guests or storage. SARAH in SARASOTA

DEAR SARAH: We have provided a plethora of barns with living quarters and every building we provide is custom designed to best meet our client’s wants and needs.

Typically, you should expect to have to two-hour fire separate barn from living area, meaning you cannot go directly from one occupancy to another without going outside in order to do so. For this reason, many of our clients have opted to have a roof only breezeway area between these dissimilar occupancies.

Spray Foam, Siding Strength, and What is DIY?

Today, the Pole Barn Guru answers questions about closed cell spray foam, which building would be stronger if one was wrapped in steel siding and the other with wood, and what aspects of a DIY project are “do it yourself”?

DEAR POLE BARN GURU: Thanks for taking the time to respond… hope this finds you doing well… I’m planning on using closed cell foam… so if I’m using closed cell I don’t have to use house wrap? I’m new to all this… so any advice you could give me would be greatly appreciated… RICKY in INDIANA

DEAR RICKY: Closed cell spray foam is best applied directly to wall and/or roof steel. Please read more here: https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/

 

DEAR POLE BARN GURU: Hey bud I wanted to pick your brain for a second. If a person built 2 steel truss pole barns the exact same… the only difference, one would be wrapped in metal, and the other would be wrapped in wood siding… which one would be stronger? The one with wood siding would be using 1×8 hemlock boards if that makes any difference. Thanks. RICKY in KINGSPORT

DEAR RICKY: It would depend upon spacing of wall girts and how each was fastened, as well as number of openings in walls. Done correctly, steel siding would be a stiffer end result.

 

DEAR POLE BARN GURU: I have seen some discussion on “price per sq. ft. to build” a barndominium you said DIY was about $85 I believe correct? When you say DIY, are you referring to like self contracting the house or self contracting and actually doing plumbing, electrical, flooring, shower install labor, etc.? LANCE in YOUNGSVILLE

DEAR LANCE: Fully engineered post frame, modest tastes, totally DIY, move in ready, budget roughly $70-80 per sft of floor space for living areas, $35 for all others. Does not include land, site prep, utilities, permits.

If you hire everything turnkey then take above numbers x2 to 3 (depends upon market). Acting as your own General Contractor and subbing everything out will put you roughly halfway between.

You will want to read #4 here before going down a “turnkey” road: https://www.hansenpolebuildings.com/2021/02/a-shortlist-for-smooth-barndominium-sailing/

 

 

Closed Cell Spray Foam Adhesion

Closed Cell Spray Foam Adhesion to Dis-similar Materials

Reader GREG in ASHEVILLE writes:

“How long will closed cell foam maintain adhesion/air barrier function to dis-similar materials (sheet metal and lumber in the case of post frame)? I ask because my experience with foam is limited to what was sprayed beneath my floor/floor joists (estimating late 70s to early 80s). The bottom of the floor joists has a membrane to hold the foam in place. When the membrane is not present, the foam can be seen as laying on the membrane/no longer attached to the wood joists/sub-floor.

I love the concept of post framing w/ foam, seems like this saves on materials and labor needed for construction. We are currently looking to build our last/retirement house, and I believe the foam will outlast me, but when it’s time to sell will the next owner have a problem with the air sealing? 

What are your thoughts?”

Mike the Pole Barn Guru responds:

In my humble opinion, engineered post frame construction is truly an answer for material, labor and energy efficient low-rise buildings (up to three stories and 40 foot tall walls or 4 stories and 50 foot with fire suppression systems).

https://hansenpolebuildings.com/2022/01/why-your-new-barndominium-should-be-post-frame/

I have researched your adhesion concern and have been unable to find any closed cell spray foam ‘coming loose’ instance.

SPF adheres to various construction materials including metal, wood, and concrete very well. However, licensed installers must ensure surfaces are completely dry, and oils, grease, dirt, and debris free as outlined in code-referenced application standards.

It is also important to assess weather when applying spray foam. While the  product may be applied in various climatic conditions, it is important to follow manufacturer’s recommendations and its Evaluation Listing installation limitations. Sprayfoam and related coatings should not be installed when there is ice, frost, surface moisture, or visible dampness present on the surface to be covered. Surface moisture can react with SPF chemicals resulting in poor-quality foam and/or adhesion lacking.

SPF system adhesion is a key field test and licensed installers are required to conduct a field test series for adhesion and density on every project, every chemical lot change, and every eight hours. These tests are conducted using field test kits installing contractors must have on their spray rigs. Test Result must be recorded on daily worksheets and submitted to their third-party certification organization for review and retention.

In some SPF insulation installations, substrate surface priming may be required, especially when applying foam to large metal surfaces. Primers can greatly enhance adhesion between SPF and existing substrates. Primers can help seal porous substrates and improve adhesion to metal substrates.

Insulation Options for an Idaho Barndominium

Insulation Options for an Idaho Mountain Post Frame Barndominium

Loyal reader LORISTON in NAMPA writes:

“We are in the initial phase of preparing for our residential post frame home and are excited to partner with Hansen Buildings when ready. Thank you for all the amazing information and supporting your clients. Question: I am targeting a highly efficient design, with >r-40 walls and >r-60 roof. There is a lot that I do not know and humble to learn from others. My mechanical engineering background helps. I would like your advice on a wall and roof design that meets my targeted R-values incorporating (from outside to inside) metal siding, >3/4″ rain screen, rock wool >2″ external insulation, Zip insulated r sheathing for WRB and thermal break/R-value increase, laminated Timber Tech glulam columns with bookshelf / commercial girts, closed cell spray foam internal insulation around 3″ thickness, fill remaining thickness from spray foam to inside edge column with insulation (recommendation would be helpful on type of insulation), internal insulation on inside of wall for thermal break if needed or helps, with final residential area having 5/8″ sheetrock and shop area having metal inside finish. We have not solved how to create a space for utilities on the outside wall as we would prefer to run them on inside of columns or thermal break insulation. We are contemplating internal framed 2×4 walls spaced away from post frame wall to create a space for utilities. No water will be run on external walls, only power, low voltage, gas, telephone as reference. Suggestion on how to run utilities with this highly efficient wall design would be appreciated. Roof is similar to wall, just horizontal with >r-60 performance, as we are targeting a conditioned attic space. Roof exception may be a second zip sheathing layer over the insulation (under rain screen/standing seam metal) but to be determined. Climate Zone 6 region in the Idaho mountains for reference. Post frame columns and wall will be on a full foundation wall with thickness based on wall design. Performance is priority over cost, targeting an air tight and efficient living space. Your experience and practical approach are greatly appreciated. Best regards and thank you.”

Mike the Pole Barn Guru writes:

Thank you for your very kind words, they are greatly appreciated.

Rather than add an expensive and structurally unnecessary concrete foundation wall, I would recommend embedded properly pressure preservative treated wall columns (as my first choice), columns above grade set into wet set brackets on concrete piers as my second. Either of these can be insulated using R-10 EPS (Extruded Polystyrene) insulation boards. I would run them on the inside of the splash plank, with the top even with the top of the slab, extending down two feet, then outward horizontally two feet.

In Climate Zone 6, I normally would not look towards spray foam as my go to choice, however conditioning your attic and your desire for air tightness come into play, so here goes:

Walls (out-to-in): Steel siding over 2×8 bookshelf girts; 4″ of closed cell spray foam applied directly to inside of wall steel and balance of cavity with either open cell spray foam or rock wool (rock wool being my preference). No internal vapor barrier or continuous interior insulation boards as we want walls to dry to interior, without trapping moisture in the wall cavity.

Roof (out-to-in): Standing seam steel over 30# felt or synthetic ice & water shield (second preferred) over 5/8″ CDX plywood. Zip sheeting is OSB and screws just do not hold well into OSB. We can specify 2×12 roof purlins in order to get a deep cavity for insulation. Closed cell spray foam 5-3/4″ (R-40) plus R23 rock wool (5-1/2″).

This combination will require mechanical removal of humidity.

My normal recommendations would be:

Walls (out-to-in): Steel siding over a Weather Resistant Barrier, over 2×8 bookshelf girts. Fill the cavity with two layers of R15 rock wool. Add R-10 EPS well-sealed on interior. This wall will now dry to the outside.

Roof (out-to-in): Through screwed steel with an Integral Condensation Control factory applied, or standing seam steel over 30# felt or synthetic ice & water shield (second preferred) over 5/8″ CDX plywood. Roof trusses with 22″ raised heels, vent eave and ridge. Blow in R-60 on top of ceiling. This eliminates the expense of heating/cooling a dead attic space.

In either instance, I would have no fears or concerns about running non-plumbing utilities within your wall insulation cavity.

Weather Resistant Barriers, LVL Notches, and Design Ideas

This week the Pole Barn Guru answers reader questions about weather resistant barriers, a caution to not attempt to notch LVL rafters, and a recommended design solution for a new build.

DEAR POLE BARN GURU: We are in process of designing our barndominium with hoping to start building next spring. Do you have a recommendation as to what water resistant barrier (WRB) to use with closed cell spray foam? Planning on using a standing seam metal roof and wainscot siding at this time. I know that a reflective barrier is useless without an air gap behind it. Using spray foam prevents its use. I’ve researched several, like zip system, Tyvek, and others. Thanks for answering my question. GREG in CARROLL

DEAR GREG: In your climate zone I would typically not recommend using spray foam other than as two inch thickness applied directly to steel roofing and/or siding in order to control condensation. This does result in having to mechanically control humidity as your building will now “dry” to inside. As standing seam steel does not provide shear resistance, it must be installed over solid decking – and you can spray foam directly to this decking underside.

In any case, it is not recommended to use closed cell spray foam applied to any WRB. For extended reading: https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/

 

DEAR POLE BARN GURU: I got a pole barn I’m putting up. The purlins were designed to run over end rafter bit that makes eve low. Can a 1 ½” x3 ½”(2×4) notch for outrigger for eave support and run end rafter up like others in the center. Notch would be 1 ½” deep on an 11 ¾” lvl. One in center span and one at top of roof. This is on the shed roofs only. MIKE in RAVENSDALE

DEAR MIKE: Absolutely do not cut or notch into your end rafter. You need to lower end rafters to allow purlins to go over top of end rafters without any notching.

While you are at it – have your building’s engineer recheck those shed rafters and purlins closest to main endwall to confirm they are adequate for snow drift loads. Usually purlins closest to endwalls have to be much closer together to adequately support those loads.

 

DEAR POLE BARN GURU: I want to space my poles 8′ apart and use to 2×12, one inside and one outside at the top to place standard trusses on the top so i can add an insulated ceiling in it. Any comments on this, and how deep do my posts have to go into the ground? LARREN in DAVIS CREEK

DEAR LARREN: Personally, I would throw away your proposed design solution.

In most instances, you are better served with sidewall columns spaced every 12 feet. Use a true two-ply truss, aligned with every sidewall column (https://www.hansenpolebuildings.com/2018/09/true-double-trusses/) and notched in. Trusses should be engineered to carry a ceiling (bottom chord dead load – BCDL). Use five (5) psf (pounds per square foot) for a steel ceiling and 10 psf if sheetrocked. Between bottom chords of pairs of trusses, joist hang 2×6 #2 24 inches on center.

In any case, raised heel trusses should be utilized to allow for full depth of insulation from wall-to-wall. https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/
Column depth will be determined by engineer who is designing your plans. They need to be deep enough to go below frost line (not an issue in California) as well as to resist overturning and uplift. Building dimensions, applied wind loads and soil bearing capacity will all impact depth of holes.

Can No Longer Afford Spray Foam for a PEMB

Can no Longer Afford Spray Foam for a PEMB

Loyal reader CINDY in TYLER writes:

“I had a steel building (20×18)  built with steel frame and metal exterior. This is going to be my house. It will have a loft that is half the size of the building. Originally the builder talked me into spray foam and that’s what Ii planned to do. He said I had to use wood to frame inside the metal walls first, then run electrical and plumbing before the spray foam. That was a couple of years ago. Now that inflation has caused prices to soar, I am simply not able to afford the spray foam. My main concern is the condensation/moisture issue. i am doing the rest of the work by myself. Since I don’t have any help it’s not going to be feasible to remove wall panels to install house wrap or insulation. So I wanted to get your expert advice on how to handle this. Specifically I have a plan to run by you. So the idea is instead of building my framing inside the metal frame, move to the inside of the metal, attach wood frame to the inside edge of the metal frame. Insulate the inside of the wood frame and add a moisture barrier to the inside of the wood frame before drywall. I will lose 3.5″ of space all around the inside but i think that will take care of any moisture issues. Please tell me what you think about this plan and make any appropriate suggestions even if you don’t post this on your blog. Also I wanted to thank you for the wealth of knowledge you have readily available on your site. Can’t tell you how much help you have been.”

Mike the Pole Barn Guru responds:

Thank you for your kind words, they are greatly appreciated.

Normally (in your climate zone of 2A) I would be recommending closed cell spray foam as insulator of choice – due to a combination of heat and humidity. Your builder headed you in a correct direction.

Before we get into how to frame your interior, we need to address what is going to happen with your roof. With steel installed directly over framing (whether wood, or in your case steel), if there is no well-sealed thermal break, you are going to experience condensation issues. You are going to have to find a way to spring for two inches of closed cell spray foam sprayed directly to the underside of your roof steel. Steel frame and steel purlins should also be sprayed. If not, you are going to have condensation on them – steel is a wonderful conductor of heat and cold.

Now – on to your question at hand. For your walls, it appears most folks do exactly as you propose and build a 2×4 wood stud wall inside of their PEMB’s (pre-engineered metal building) steel wall girts. You will want to completely fill your wall cavity with insulation – I would recommend rock wool, as it is not affected by moisture (here is information on one particular product https://www.hansenpolebuildings.com/2013/03/roxul-insulation/). You want to make sure your interior vapor barrier is extremely well sealed, including outlets.

If you do not have a well-sealed vapor barrier under your slab on grade, please seal your concrete now. Your HVAC system should be designed to mechanically dehumidify, else condensation is going to haunt you forever.

Insulation and Ventilation, Straw Bales, and Double Bubble

This week the Pole Barn Guru answers reader questions about using cardboard and heavy plastic to vent and insulate a pole building, use of straw bales an insulator, and best way to ventilate and reduce roof noise.

DEAR POLE BARN GURU: On my 42×63 2 story pole building (heated first floor) I have trusses 9’ o.c. standard roof purloins 2’ o.c. I was wondering if I could use cardboard up against steel roofing for venting air flow of the humps in the steel roof panels (standard steel w/ 1” humps not standing seam ) then install heavy plastic on bottom of purlins and fill cavity w/ cellulose blown insulation. Would this work correctly for ventilation of steel and insulate correctly. Combination of being cheap/frugal and I have free heavy cardboard from washers/dryers/refrigerators to fit between purlins. Greatly appreciate your opinions. Thank you. BEN in EDEN

DEAR BEN: Code requires a one inch minimum of airflow across your entire roof surface above batt insulation. Air flowing only at steel ribs would be inadequate to meet requirements. Assuming you have 2×6 roof purlins, 5-1/2 inches of blown cellulose would give you roughly R-19.25. You would be better served by using 2-1/2 to 3 inches (R-17.5 to R-21) of closed cell spray foam applied directly to underside of your roof steel, as it does not have to be vented above.

 

DEAR POLE BARN GURU: Hi, I read your post on bale infill with a pole building (https://www.hansenpolebuildings.com/2013/04/straw-bale-homes/). When I called to get more info, the rep told me that Hansen strongly advises against it, but he also said he hadn’t heard about that idea. Is there someone there that has worked with a client who has used straw bale walls to infill between the posts? KEVIN in RENO

About Hansen BuildingsDEAR KEVIN: Your call happened to be routed to one of our newer Building Designers. Post frame construction is highly complex, with a literal unlimited number of possibilities, this being one your designer was unfamiliar with.

In general straw bale homes seem to have been a passing fad, however if you strongly feel this is your best option, please call again and ask to speak with Rachel – our most senior Building Designer, and she can assist you better.

 

DEAR POLE BARN GURU: I am looking for a underlayment for my pole barn. I have metal roofing with horse stables below. There are no side walls to my pole barn. It’s all about ventilation for the animals here in NC. It’s supposed to add a few degrees in R value. It also helps deaden the sound of rain. Everyone talks about double bubble but this is supposed to be different. Thank you, FRANCES in TRYON

DEAR FRANCES: Without having to pull off your building’s roof steel, install some fashion of condensation control then reinstall it – there is only one practical solution – two inches of closed cell spray foam applied directly to underside of your steel roofing. This would provide an R-14 insulation value. It is unlikely to have an effect on reduction of noise from rain, as it is not good at blocking sound waves. “Double bubble” offers little to no R-value and would require being installed between framing and roof steel.

 

Condensation Control, a Bottom Track, and New Steel

This week the Pole Barn Guru tackles reader questions about adding condensation control to an existing structure, the installation of the “bottom track” of a sliding door, and how to finish an existing structure with wrap and steel.

DEAR POLE BARN GURU: hello – I just bought a large Amish shed for a workshop, and a cottage – I was a bit worried about the metal being directly screwed to purlins with no underlayment but bought then anyway… Is there any way besides spray foam to insulate and prevent condensation from the inside now? I assumed I could put closed cell rigid fiberglass between the rafters…am I wrong? ROBERT in LEBANON

DEAR ROBERT: Lack of a condensation control is probably problem number one when it comes to builder/installers selling on low price, rather than a great value.

Your best solution will be two inches of closed cell spray foam applied directly to underside of roof steel. You could try to use rigid insulation panels, however to be effective you will need to insure there are no gaps allowing warm, moist air from inside of your building to reach roof steel. This usually involved hours of patient and perfect cutting, working from ladders or man lifts, and lots of sealants.

 

DEAR POLE BARN GURU: How does the bottom track of sliding doors work so that you aren’t running over it when you have a concrete pad under barn? MISTY in CLIFTON

DEAR MISTY: Properly designed, sliding barn doors do not have a bottom track resting on top of your barn’s concrete slab on grade.

Your sliding door metal girts should look like this:

They are installed with slots down (towards ground).

Mounted to wall in direction door opens will be a guide rail.

Guide rail is inside of slot in bottom door rail, preventing sliding door from swinging outward away from building, or banging into siding.

 

DEAR POLE BARN GURU: Hi there,

I have a 12×24 pole structure that was used as cover for some horses on the property I just bought and I want to finish it up.

They put a roof on it with asphalt shingles that is in good shape, but they simply put 7/16 OSB on for the walls and called it good. It’s about 5 years old. Surprisingly only a few of the OSB panels are swelled up from the elements which I have replaced.

I want to put metal siding and roofing on it.

I was going to lay some fanfold insulation down on the roof to create a flat surface for the metal. Any other suggestions? I don’t want to rip off all the shingles if I don’t have to.

For the walls would you recommend putting a building wrap around the OSB to protect it and then put the siding up? I’m not planing on insulating it. Was debating if it was needed at all.

This is in Spokane WA. Hot dry summers and dry cold winters.

Thanks, BRYCE in SPOKANE

DEAR BRYCE: Having been born, raised and spent most of my adult life in Spokane, I am vastly familiar with your weather.

In order to achieve a smooth surface for installing steel, place 2×4 flat on top of existing shingle roofing and nail through into underlying roof rafters or trusses with at least two 3-1/2″ galvanized nails or structural screws no less than every two feet. Do not rely upon attaching these only to sheathing. Fan fold insulation, by itself, will not provide an adequately smooth surface.

Building wrap is cheap – if in doubt, do it. Make sure to screw wall steel thru OSB into underlying wall girts (longer screws will be required).

Condensation Prevention, Sound Proofing, and Snow Loads

This Wednesday the Pole Barn Guru tackles reader questions about condensation prevention by placing foam board over the top of 2×4 purlins, options for sound proofing a post frame home, and if 2×4 flat purlins can hold a specific snow load.

DEAR POLE BARN GURU: I am planning a pole barn; the roof will have 2×4 purlins spaced 24″. I plan on putting 1/2″ foam board (faced on both sides) over the purlins with the seams taped. Then putting metal panels over the foam board. Will this be sufficient to prevent condensation from dripping within from the roof? JIM in MIDLAND

DEAR JIM: Good news and bad news…. while your proposed solution will likely take care of possible condensation issues, it is structurally unsound. Post frame (pole barn) buildings rely upon shear strength of steel roofing and siding in order to remain stable. When you add in even a half-inch gap of non-rigid material (foam board) between framing and steel skin, you greatly reduce (or eliminate) shear strength of your steel panels. Even if your building were to remain standing, shifting of steel panels with small diameter (#9 or #10) screws will cause slots to form around screw shanks, eventually causing leakage.

You would be best served to order roof steel with an Integral Condensation Control (read more on I.C.C. here https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/) factory applied. It will be less costly, easier to install and not cause negative structural issues.

 

DEAR POLE BARN GURU: Afternoon! Thanks for all the great info in your blog. It has really helped me plan my new home. I have one question: I’m having a post frame home built and am wondering about soundproofing. The roof(s) will be steel directly on purlins with a radiant barrier in between. The conditioned space will have R-60 blown-in fiberglass above it so I’m not worried about that. What I am concerned with are the front and rear porches. The front will have a, 8″ shed roof porch and the rear will have a 16×16 gable-roof screened porch. Both will have finished ceilings, steel and knotty pine respectively. I’d like to be able to sit under either when it’s raining and it not be loud. What would you suggest I do to mitigate the drum effect in an uninsulated porch? I’ve thought about using rockwool batts, maybe mass-loaded vinyl, or even painting the underside of the steel with liquid rubber before the panels are screwed down. Any advice? Thanks much. PETER in HUDSON

I am pleased my information has proven helpful to you. I would consider one of two options – installing steel in these two areas over solid sheathing (OSB or plywood) with 30# felt or a synthetic underlayment, or using two inches of closed cell spray foam applied directly to underside of roof steel. Either of these should assist in mitigating sound.

 

DEAR POLE BARN GURU: In an area with a 50 p.s.i. snow load ground rating and trusses 4′ o.c., can 2×4’s 2ft. o.c. be laid flat for roof purlins? STEVE in WYOMING

DEAR STEVE: Maybe – this will depend upon numerous factors including (but not limited to):

Risk Category of building
Roof slope
Wind Exposure
Roofing material
Snow retention systems
If building is heated or not
Available grade of lumber

Ultimately this decision should be made by whomever your engineer is who is sealing your building plans. Special care should also be taken to insure adequacy of purlins in drift zones (closest to ridge), where purlins may need to be closer spaced, higher grade and/or larger dimension material.

Also – ground snow loads (Pg) are typically expressed in p.s.f. (pounds per square foot), rather than p.s.i. A p.s.i. of 50 would equate to 7200 p.s.f

Spray Foam, Second Floor, and Bending Posts

This week the Pole Barn Guru discusses a reader’s concern about “condensation leaks” when using spray foam, advice on costs of attic trusses vs traditional second floor, and how to stop posts from bending when the wind blows.

DEAR POLE BARN GURU: I am building a 40×50 post frame building as my garage. It will have concrete floors and HVAC. I intend on insulating the entire building (walls & ceiling) with closed cell spray foam. I’ve read a lot about people having condensation leaks, so my question is: Should I wrap the walls (and/or ceiling) with Tyvek or spray foam directly to the metal? Second question is should I use plywood on the roof for better structure and to have something to spray foam to? Any advice is appreciated. Thanks. CHRIS in BLOOMFIELD

DEAR CHRIS: Closed cell spray foam is a great product, however it would not be my first choice for your climate zone. For best results, closed cell spray foam should be two inches or thicker to prevent condensation, and applied directly to the roof and wall steel. Hopefully you have a well-sealed vapor barrier beneath your building’s slab. With closed cell spray foam, you may experience condensation on your building’s interior, so do not be surprised should you have to mechanically dehumidify. Unless specified as necessary on your engineer sealed building plans, you should not add plywood or OSB to your roof system, as it will add unexpected dead loads to your building system.

 

DEAR POLE BARN GURU: Hello. We are wanting to build a 2 story pole barn winery. First floor winery and second would be air-bnb type rental. We aren’t sure if we should use attic truss or complete the build with a traditional second floor. Cost is probably biggest concern. Space second as we know attic truss would be less room. Would you do an attic truss or traditional 2nd floor type build and roughly cost difference between the 2? Building size will be roughly 40×60. Thank you for your time. CRAIG in ROCK CREEK

DEAR CRAIG: If cost is your biggest concern, then having rental on ground floor will be least expensive, easiest to climate control, more accessible for your guests and easiest to fire separate from your winery.

If your only option is to have rental above winery, going with a second floor type build is going to give you far less costly investment per square footage of rentable space.

 

DEAR POLE BARN GURU: I built a pole barn for my r/v a couple of years ago. I used 4×4 for my posts with a metal roof and purlins with no siding. The posts are set 3′ into the soil with no concrete. Posts are 10′ out of the ground. When we get a strong wind the posts bend slightly at ground level allowing the structure to flex. Is there a way to add strength to the posts or do I need to replace with a larger size post and should I embed the post in concrete or will it rot? MARK in BRADENTON

DEAR MARK: I am frankly amazed your building is standing! This response is not to be taken as a replacement for an actual engineered structural design and should be verified by an engineer prior to moving forward. You should replace 4×4’s with at least 6×6 (it may require 8×8’s depending upon design wind speed and exposure at your site) #2 Southern Pine columns pressure preservative treated to UC-4B (there will be a treating tag on one end of each). Columns should be at least 40″ in ground and backfilled with pre-mix concrete.

Retro Installing Windows in a Spray Foamed Post Frame Building

Retro Installing Windows in a Spray Foamed Post Frame Wall

Reader JOEY in PRINCETON writes:

“Good Evening Pole Barn Guru! We need to add picture (9) and slider (3) windows to an existing 3-year old Sherman Pole Building Post frame building where we are converting part into living quarters. The building was spray foamed by the previous owner with closed cell foam, and upon some investigation (and confirmation by the builder – Sherman Pole Buildings) house wrap was not used. We need to order the windows for spring installation and are wondering how and what kind of windows to use. A salesman at Menards flippantly recommends using windows with a nail flange without brickmold. To assist our carpenter who will do the installation (with my assistance) I have searched high and low on the internet for a way to install the windows, but all I find are instructions on installation before steel is installed, and nothing with regards to existing spray foam insulation that is adhered to the steel. We realize we will need to scrape the foam insulation, so we are ready for the work involved. What advice can you offer? Do you have a window vendor to recommend? It would be greatly appreciated. I’ve attached pictures for your reference, Thanks for all your help.”


Mike the Pole Barn Guru says:
Joey is finding some challenges involved when it comes to doing a conversion from a barn to living quarters. Most post frame barns and accessory buildings are not engineered for residential structural requirements and unless one is 100% confident they have been appropriately engineered, a Registered Professional Engineer should be engaged to do a thorough site inspection and advise as to adequacy or structural repairs/upgrades.

I have given your situation a great deal of consideration, trying to weigh all involved factors of costs of materials, labor involved and end result. Here is what I would do:

In each bay (area between two columns) where an opening needs to be added, I would completely demo wall. Remove all insulation, girts and siding. I’d order replacement steel panels, install new girts, framing in new window openings, etc. New vinyl windows should be ordered with integral J Channels (sometimes referred to as J trim attached). These can be from any manufacturer and should be gas filled Low-E windows. Personally I feel it worth opting for triple pane windows in our climate. Going this demo and rebuild route will allow for sloped sill pans to be placed and self-adhesive flashing tape to be utilized.

In defense of your ‘Big Box’ salesperson – box stores and lumber dealers are unable to compensate help well enough to acquire, train and retain truly knowledgeable help.

Trying to scrape off your existing closed cell spray foam cleanly would be at very least a daunting task and is likely to damage some or all of your panels being scraped. Your only way to cut steel to properly fit windows snugly takes removal of steel panels, full length, as they need to be slid into place alongside windows.

A Walk-Out, A Shouse, and Spray Foam Insulation

This Wednesday the Pole Barn Guru addresses reader questions about the possibility of Hansen designing a walk-out basement, building a Shouse, and a consideration of spray foam insulation.

DEAR POLE BARN GURU: Do you do walkout basement? DIANE in WARRENTON

About Hansen BuildingsDEAR DIANE: Absolutely we can provide your barndominium with a walkout (daylight) basement: https://www.hansenpolebuildings.com/2020/02/barndominium-on-a-daylight-basement/
We have also developed the technology to incorporate a Permanent Wood Foundation between columns on sides where you are cutting in. This greatly reduces amount of required concrete, saving you money!

 

DEAR POLE BARN GURU: I have been dreaming of a 56 x 32 work shop at my home. I have the urge to build a 2 story structure with the lower floor having a 16 foot wall height so a lift can be use as well as a car stacker. the upper floor could be an 8 – 10 foot wall height being used for storage and wood working and maybe a man cave type room. Is such a monstrosity buildable…can you help me with this? Thank you for your time, GEOFF in RAPID CITY

Gambrel roof pole barnDEAR GEOFF: This can totally be done – my own personal shouse (shop/house) has a 16′ ceiling downstairs, and upper level clearspans 48′ across so there are no columns to negotiate. Storage and wood working can be heavy, plus you have the efforts of having to move materials in and out far above ground. Provided you have space on your property, you would be far ahead to put all of this space on one level – access will be easier, you won’t burn up space to stairs, etc.

 

DEAR POLE BARN GURU: I am looking to build a garage/workshop for year round use, so I am considering foam insulation.
I am leaning towards 2″ closed cell foam, then a 2×4 wall with batt material so there is no direct transfer of heat/cold.
I read that almost everyone recommends house wrap under the metal walls then spray foam in case a section of metal wall needs to be replaced in the future.
My question is: Should I also include house wrap for the roof in getting my estimated cost? Will the spray foam stick to the roof wrap or should it be applied directly to the metal?

Thank you for helping me with this, BILL in OAKDALE

DEAR BILL: Closed cell spray foam is a great product and is best applied when sprayed directly onto steel roofing and siding. https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/

Steel with closed cell spray foam directly applied would have to take one monstrous hit to be damaged – enough so as you are probably replacing far more than just the panel and should be filing an insurance claim.

In your climate zone, this is what I would typically recommend:

ROOF: Order steel roofing with an Integral Condensation Control factory applied. Order roof trusses with 22″ raised heels, blow in R-60 fiberglass on top of ceiling. Enclosed vented soffits and vented ridge

WALLS: Weather Resistant Barrier between framing and wall steel, bookshelf wall girts, minimum R-20 unfaced batts (I prefer rock wool), well sealed R-5 rigid insulation on interior

SLAB: Perimeter R-10 rigid insulation down 4′ (or 2′ down, then out from building to follow Shallow Frost Protected Foundation requirements).

Roof Insulation, a Riding Arena, and Closure Strips

Today’s Pole Barn Guru answers reader questions about insulating a roof to keep exposed trusses, the size limits for and equestrian riding arena, and whether or not to use closure strips between the gable (rake) trim and siding.

DEAR POLE BARN GURU: I have a 30×40 post frame building with cathedral style trusses. I really like the open look and don’t want to cover them with a ceiling. I want to insulate against the metal roof with vinyl faced blanket insulation to give a nice finished look. The roof currently has bubble wrap which I’m told I should remove so I don’t have two vapor barriers. Question is, if I remove the bubble wrap, is it ok to lay just blanket insulation between trusses or should I try to fill the 1.5″ space between purlins with foam board then blanket insulation over top of foam board. Or would filling the 1.5″ space with spray foam, then blanket over that? Thanks for any advice. BRIAN in LANDISVILLE

DEAR BRIAN: Only way to properly do as you propose is to remove bubble wrap, then have 2″ or more of closed cell spray foam insulation applied directly to underside of your steel roofing. Balance of insulation cavity can be filled with either more closed cell (best R value) or rock wool insulation (as it is impervious to moisture).

 

DEAR POLE BARN GURU: Need an open cover 150 L x 75 W x 13 H to function as a cover for an equestrian arena. Can a pole barn get this big? And if not what is the largest size we can go. JEFF in PINELLAS PARK

DEAR JEFF: While we have provided post frame riding arenas with up to 100 foot clearspans, in most geographical areas, wood truss fabricators are limited to building and shipping lengths up to 80 feet and overall truss heights of 12’.

Interior Clearspan Arena

For extended reading on riding arenas, please visit: https://www.hansenpolebuildings.com/2012/07/the-perfect-indoor-riding-arena/

 

DEAR POLE BARN GURU: Should I use closure strips between the gable trim (rake trim) and siding? The siding is tuff rib. STEVE in WARREN

DEAR STEVE: Standard form fitted closure strips are sized to only fit perfectly when applied at 90 degrees to length of steel panels. When going up rake trim, these closure no longer fit, however we have a perfect solution Emseal! https://www.hansenpolebuildings.com/2016/03/emseal-self-expanding-sealant-tape-closures/
To acquire, please reach out to Materials@HansenPoleBuildings.com along with lineal footage required and ship to zip code.

 

A Barndominium Challenge

A Barndominium HVAC Challenge

My now dear friend (thanks to his barndominium) LONNIE in COLORADO SPRINGS writes:

“Hi Mike, I’m still around and still working on the house and making some slow but constant progress so I thank you all for your help and support. I have run into an issue (it’s not related to my Hansen building but I’m hoping you can offer advice anyway).. I ran into a problem getting a HVAC contractor to install my HVAC system. Not too many companies are willing to work with a owner/builder and HVAC install is way out of my wheelhouse. I was able to find a contractor that was willing to do the install but they were pretty much unwilling to do anything different than their “normal” installation (i.e. supply and return ducts in the attic). I was really wanting to do at least return air in my conditioned crawl space but they wouldn’t even consider doing that. So, in order to make progress on the project, I okayed the installation. All the building guru’s say that HVAC duct should not be placed in an unconditioned attic due to leakage and inefficiency so I’m trying to figure out how to mitigate duct losses. There are a couple of ways that I’ve thought of but I’d like your thoughts.

Options:

1: As described in some articles I’ve read and encapsulate all the ductwork with spray foam then bury all the ducts in my blown in insulation

2: Just leave the ducts as is and just bury the ducts as deep as I can afford with insulation3: I’ve thought of covering all the ducts with 6 mil plastic down to the ceiling drywall.. i.e. kind of enclose the ducts in a bubble that is attached to the ceiling, then bury it all in insulation. Covering the ducts in plastic seems like it would basically move the ducts to the conditioned space. Anyway, thank you for all your input and all the help you guys have been to me.

Thanks Lonnie”

Lonnie ~

Mike the Pole Barn Guru responds:

You are most certainly among my favorite all time clients, it has been such a pleasure working with you. While I am excited for you to be moving in, I have to admit it will be sad to not hear from you once all is completed. Since you started, one of our sons has moved to Colorado Springs, so if we get down to visit, I will drop you a message and maybe come by to see your beautiful home for real.


Your HVAC experience is why our Construction Industry in general is so far behind the curve of efficient building design – very frustrating. I would look to make those ducts as efficient as possible – I’d start with two inches of closed cell spray foam on sides and top, then bury it with enough blown in insulation to achieve an R value equal to the balance of your attic space. Closed cell spray foam will seal up any leaks in your duct work (trust me, there will be some). Return air through your crawl space would have been a no-brainer, in my humble opinion. I worked with stick frame builders nearly four decades ago who insulated their crawl space perimeters and then used those crawl spaces as one huge air return. Then, it was less expensive than running ducts.

Wet Set Brackets, a Walkout Basement, and Rigid Foam Issues

Today’s Pole Barn Guru tackles reader questions about using wet set brackets on a stem wall foundation, if it is possible to build over a walkout basement, and the viability of installing rigid foam between framing and steel cladding.

DEAR POLE BARN GURU: Hey there guru. We are planning on building a post frame home next year. Now for my question/s. Is it possible to use wet set brackets for posts on a block stem wall foundation? I also had the thought of marrying posts with brackets to a conventionally anchored double sill plate? If using a pier and wet set brackets system… Can a person do a raised floor design? And if so how would one keep the bugs and critters out of the “crawl space”? BRAD in SWANVILLE

DEAR BRAD: Wet set brackets can be poured into properly engineered and constructed block, concrete or ICF stem walls. In order to resist uplift forces, brackets are best installed directly into top of walls, with a properly pressure preservative treated sill plate between columns to attach siding to.

When using a pier and bracket mounted column system you can most certainly do a raised wood floor (crawl space) design. Any crawl space would require encapsulation (read more here https://www.hansenpolebuildings.com/2020/11/11-reasons-why-barndominium-crawl-space-encapsulation-is-important/) by Building Code. A non-decaying barrier to prevent burrowing creatures would also be prudent (https://www.hansenpolebuildings.com/2012/06/rat-wall/). My recommendation (and we can show this on your engineer sealed plans provided with your building) would be to use 19 gauge, 1/2″ x 1/2″ galvanized wire mesh around your building’s perimeter to a depth of three feet. This can be done be means of a trench and will be far less expensive than pouring a wall between columns.

 

DEAR POLE BARN GURU: Can I put a walkout basement under a steel frame residence?
JEN in HARTFORD

DEAR JEN: While I would have no idea on what sort of engineering it would take to mount a PEMB (Pre-engineered Metal Building) to a walkout basement, fully engineered post frame buildings can be designed to incorporate a full, partial or walkout basement. Read more here: https://www.hansenpolebuildings.com/2020/02/barndominium-on-a-daylight-basement/

 

DEAR POLE BARN GURU: Hello, I am considering building a cabin using pole-construction. I was wondering is it possible to use rigid foam insulation between the outside of the structure and the roof/wall cladding? GILES

DEAR GILES: Placing rigid foam insulation board between framing and cladding is not structurally a good choice. Post frame buildings work due to shear strength of their ‘skin’. When a non-structural sheathing is added it allows for fasteners to deform between cladding and framing, reducing shear strength, causing elongation of holes in siding/roofing and potentially a failure condition. You would be better served to use two inches of closed cell spray foam on inside of cladding after your cabin is erected.

 

 

 

 

Floor Plans, Spray Foam for Condensation, and a Sill Issue

Today the Pole Barn Guru answers reader questions about floor plans, adding spray foam to an existing structure for condensation control, and solutions for a sill at 18′ OHD opening.

DEAR POLE BARN GURU: What do you charge to take my floor plan and send me engineered drawings? SHANNON in JONESBOROUGH

DEAR SHANNON: We only furnish engineer sealed plans and verifying calculations with your investment in a new Hansen Pole Building. If you just need professionally done floor plans, please check this out: http://www.hansenpolebuildings.com/post-frame-floor-plans/?fbclid=IwAR2ta5IFSxrltv5eAyBVmg-JUsoPfy9hbWtP86svOTPfG1q5pGmfhA7yd5Q

 

DEAR POLE BARN GURU: Hello! I have recently purchased a pole building that is not insulated & It does not have the vapor barrier/plastic installed between the wood framing and the sheet metal. We would like to insulate this building. We are thinking spray foam because I have heard you can apply it directly to the steel. Do we have any other options for insulating this? Any advice is greatly appreciated. Thank you!! KRYSTA in SPOKANE

DEAR KRYSTA: If it has no sort of condensation control between roof framing and roof steel then two inches of closed cell should be sprayed to underside of roof steel to control condensation. If your roof trusses are designed to support a ceiling, then install one and blow in R-60 fiberglass on top of it, ventilating the dead attic space appropriately.

For your walls, you can use rock wool insulation batts, completely filling wall cavity, with a well-sealed vapor barrier on interior face.

 

DEAR POLE BARN GURU: I need to pour a concrete sill at the 18’ wide entry to my pole shed in South central Wisconsin. The interior of shed is compacted crushed limestone, the apron leading up to it will be asphalt so a concrete sill seems like a good idea to protect asphalt edge. I can’t find any advice online so I hope you can help me out with your expert thoughts. First, good idea? Second, thickness. It would be about 12” wide. The base is 30 years old, thick and well compacted. Any help would be greatly appreciated. Thanks for your time. JAPH in WISCONSIN

DEAR JAPH: My concern would be possible frost heave of a concrete sill. I would probably excavate outside my building so top of asphalt and top of interior compacted crushed limestone were at same grade and call it good. Takes away possible heave of concrete and saves cost of concrete.

 

Uneven Ground, Greatest Strength, and Post Spacing

This Monday the Pole Barn Guru answers reader questions about building a pole barn on uneven ground, if spray foam adds the greatest strength, and post spacing for a roof only porch.

DEAR POLE BARN GURU: We were potentially looking to build. We were investigating our options and I came across pole barns. My potential issue is the land I would be potentially building on. Its on a hillside and not exactly flat. Is this an issue with pole barns? As most of the photos of homes are on flat ground. LESLEY in HAZARD

DEAR LESLEY: Fully engineered post frame (pole barn) buildings can be adapted to fit most any ground surface – from pancake flat to steeply sloped. Many design solutions are possible: cutting into hillside (will require a retaining wall outside of building perimeter or a foundation of concrete, block, ICFs, or pressure preservative treated wood); a combination of cutting and filling; filling to bring site up to highest grade (this is most common and minimize possible affects of exterior surface water infiltration) or as a stilt house.

Here is how I personally solved 12 feet of grade change for my own shop/house: https://www.hansenpolebuildings.com/2012/02/grade-change/

 

DEAR POLE BARN GURU: What would give pole barn the greatest strength- closed cell exterior walls or under roof?

Due to cost would closed cell under metal roof and open cell on all walls provide much additional structural support?

Would close cell all but price prohibitive so looking at next best option.

CAM in DANVILLE

DEAR CAM: In order to insure your post frame (pole barn) building has its greatest structural integrity, it should be fully engineered (not just trusses) to meet or exceed Code mandated design wind speeds and Exposure for your site. While closed cell spray foam insulation will make any surface it is directly applied to more rigid, I would not rely upon it as a structural solution.

Your site is located in Climate zone 5A. 2018 IECC (International Energy Conservation Code) requirements for residential energy efficiency specific R-49 for ceilings, R-20 for walls. For cost effectiveness you could do a Weather Resistant Barrier in your walls between framing and steel siding, then fill balance of wall cavity with kraft faced fiberglass R-21 batts. For your roof, order trusses with 18 inch energy heels designed to support a ceiling and blow in 16 inches of fiberglass on top of your ceiling. Control condensation with a well-sealed Reflective Radiant Barrier (least expensive for materials but more work) or an Integral Condensation Control applied directly to roof steel when roll formed (slightly more for materials, but easily installed). Provide adequate ventilation with intakes through vented sidewall soffits and exhaust at ridge.

 

DEAR POLE BARN GURU: Can I build a 24×24 gabled roof over my deck using only four posts? RON in TRUMANN

DEAR RON: It might be possible, but may not be practical as you are going to need to have 24′ long lumber for either purlins, or truss carriers. Chances of being able to acquire either, without purchasing full unit quantities, will be slim. We would typically recommend using 6 columns, spaced every 12′ along eave sides.

 

 

Spray Foam, Crawl Space Floors, and Column Sizes for Shed

This week the Pole Barn Guru answers reader questions about spray foam application of a vapor barrier, finishing a crawl space floor, and to go with 3 ply or 4 ply columns– this is dependent upon many things.

DEAR POLE BARN GURU: New Construction – Can spray foam insulation be spray over a vapor barrier blanket in the roof of a pole barn, too increase insulation rating?

Thank you, TERRY in WILSONVILLE

DEAR TERRY: In your part of our world, most often roof condensation is controlled by use of what is known as a “Condensation Control Blanket” – a thin layer of fiberglass bonded to a white vinyl backing. When laps are properly sealed (rarely done right) it does make for an effective vapor barrier, although it provides minimal, at best, insulating value.

I am not a fan of spray foaming to any flexible barrier in walls or roofs (https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/).

My first choice would be to design your building to be capable of supporting a ceiling, use raised heel trusses and blow in fiberglass insulation. With raised heel trusses you can get full thickness from wall-to-wall and you do not end up heating dead space between roof trusses. Roof steel should be ordered with a Integral Condensation Control (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/) and adequate ventilation provided at eaves and ridge.

Second choice would be to omit condensation blanket and Integral Condensation Control and use two inches or more of closed cell spray foam directly to underside of roof steel. This will not be nearly as effective as choice number one.

 

DEAR POLE BARN GURU: After reading several articles on your website I’m leaning towards building a single story post frame home with about a 4 foot crawl space so that I get benefits of a floor not hard on the joints and access to any plumbing or electrical if things go wrong. I would also like to build as close to a passive or net zero home (within a reasonable budget) but was wondering how to do that with a dirt floor crawl space. I’ve read that the best way is to keep crawl space within the envelope of the home but I’ve only read of a vapor barrier that is covering the dirt floor. Thanks for all your help. TODD in HENNING

DEAR TODD: Thank you for being a loyal reader. My knees and your joints must be related – as nothing pains me more than standing on a concrete floor for even relatively short periods of time.

Most crawl spaces are created with dirt floors, face it, they are low budget and meet Code with a 6mil black Visqueen Vapor Barrier installed. Now retired Hansen Pole Buildings’ Designer Rick Carr built himself a hunting cabin over a crawl space a year ago and decided to take a slightly different route. He opted to do a thin layer of concrete to cover ground in his crawl space, with an idea of being able to roll around using a mechanic’s creeper, should he need to work on sub-floor utilities. Here is an excerpt from part of Rick’s planning: https://www.hansenpolebuildings.com/2019/03/pole-barn-cabin-part-ii/

 

DEAR POLE BARN GURU: I am putting up a 60x135machine shed. 18 ft sidewalls, I’m wondering if the 3 2×8 laminated columns are enough or if i should spend 2900.00 more to go to 4 2×8 columns. thanks, SHANE in ASHTON

DEAR SHANE: Your question leads me to believe you are attempting to make a hundred thousand dollar plus building investment, without benefit of fully engineered structural plans.

Column sizes will be dictated by effects of column spacing, design wind speed and exposure (an Exposure C site being subjected to 20% greater wind forces), roof snow loads, dead weight of roof system (including any ceiling), roof slope as well as proper diaphragm design of your building shell.

I will implore you to please, please, please build only from a fully engineered plan. Think of it as an investment into one-time insurance. I only want to see you put this building up one time.

Roof Insulation, Pole Barn Houses, and Adding Heat

Today the Pole Barn Guru tackles reader questions about the best method of insulating a building with no plans for a ceiling, planning a pole barn house, and adding heat to a completed post frame building.

DEAR POLE BARN GURU: I am insulating my 30×50 pole barn that is wrapped with Tyvek outside the purlins and I will use faced batt insulation on the 10ft walls. I will have it heated in the winter with the gable vents and cupola closed when working, but will not cool it in summer months. My question is what is the best method to insulate the roof as I don’t plan to add a ceiling? Currently, there is a radiant barrier on top of the roof purlins directly below the metal, and the only venting is the cupola and two gable vents. ERIK in FESTUS

DEAR ERIK: Without a ceiling I would have recommended two inches of closed cell spray foam applied directly to your roof steel – except you have a radiant reflective barrier in place (not a best thing to spray foam to). This method also means it would be nice and toasty between your trusses, but not so much in your working area.

Provided your roof trusses are capable of supporting weight of a steel liner panel ceiling, I would encourage you to consider it as an option, then blow fiberglass insulation in above liner panels. Alternatively, you could use lathe, wire mesh, or other means across bottom of trusses and place unfaced batt insulation on top.

 

DEAR POLE BARN GURU: I would like to know about building a pole barn house. 3 bed 1.5 to 2 bathroom. If I order from you do I build it of you? How much do they cost? DAVID in KALKASKA

DEAR DAVID: This article should get you started https://www.hansenpolebuildings.com/2021/02/a-shortlist-for-smooth-barndominium-sailing/

 

DEAR POLE BARN GURU: Heating an unvented barn? I have a 52×70 Hansen pole barn. I have decided I would like to heat the space. I have sealed the concrete and have spray foamed the walls with 2.5″ closed cell and blocked the soffit vents while doing this. I will be using a combo of a waste oil furnace and a wood stove to heat the space. My question is can I block off the gable vents instead of putting in a ceiling? Will I have moisture issues if I do this? I did use the foil insulation between the roof sheeting and the purlins that came with the package. Thanks. MARSHALL in CAMANO ISLAND

DEAR MARSHALL: Please keep in mind the Reflective Radiant Barrier under your roof steel is a thermal break designed to control condensation from occurring on underside of your roof steel, it is not insulation and has a R value of roughly one (R = 1). If you block off all vents, you may need to mechanically dehumidify your space in order to reduce moisture inside. Alternatively, should you install a ceiling and insulate above it, you would need to appropriately vent dead attic space to prevent roof system mold and mildew.

 

 

 

 

Stamped Plans, Bottom Chord Loads, and Spray Foam Options

This Monday the Pole Barn Guru answers reader questions about engineer stamped plans,  hanging sheetrock of OSB from truss bottom chords, and the best choice for spray foam insulation in a post frame building.

DEAR POLE BARN GURU: Are your drawings engineer stamped to meet local municipality requirements? ERIK in LAS VEGAS

Engineer sealed pole barnDEAR ERIK: Yes, our structural plans, sealed by our independent third-party engineers are designed to meet or exceed loading requirements for each individual building’s jurisdiction. We have provided several buildings in Clark County, including the giraffe barn at your Lion Habitat Ranch in Henderson. We do always have our clients verify load conditions with their Building Department prior to ordering. This will give you an idea of what will be on form to be completed: https://www.hansenpolebuildings.com/2020/08/building-department-checklist-part-i/.

 

DEAR POLE BARN GURU: Can I hang 7/16″ osb or 5/8″ sheetrock from my pole barn style garage with 4′ on center trusses with a 2×4 bottom chord & 2×6 top chord & a 28′ span? I have thought of running 2×4’s perpendicular to the trusses but am concerned about all the weight. Any thoughts or ideas for me? DAVID in HELENA

DEAR DAVID: If your building’s roof trusses have been designed for at least a five psf (pounds per square foot) bottom chord load (often shown as BCDL on engineered truss drawings) then they could support weight of either 7/16″ OSB or 5/8″ sheetrock. Neither product is designed to span greater than two feet, so you would have to add framing between trusses to adequately support.

This circumstance is why all Hansen Pole Buildings prefabricated wood roof trusses spanning 40 feet or less are designed with a minimum BCDL of five psf or more – just an added service for our clients who decide to add a ceiling later on.

 

DEAR POLE BARN GURU: I have read many, many of your replies pertaining to the multitude of insulation questions to try and find a scientific and experience answer to an insulation quandary my daughter will experience in a matter of days. I am very familiar with & proficient in stick build & the associated vapor & breathing issues in that form of home building. However, the post & frame discipline is different & yet has some similarities in physics. My daughter & son-in-law are already in contact to have 4″-5″ of “open-cell” spray foam for insulation for walls & roof. I completely understand house wrap, condensation etc….my question is this. Should Tyvek be used between the metal sheathing (siding) & the open- cell or not? The trusses are spaced 2ft o.c. & 2×4 purlins are laid flat 2ft. o.c. then standard girt spacing, etc. on walls. I just want to make sure I provide my daughter with the correct answer so as her family can live in their home with the concern. I thank you for your time and expertise. NICK in MORRIS

DEAR NICK: Luckily physics remains same from stick built to post frame!

For walls – my preference would be two inches of closed cell sprayed directly to wall steel, then fill balance of wall cavity with unfaced insulation of your choice. Fiberglass would be least expensive for this, although open cell spray foam or BIBs are options (I have done BIBs personally and think it is great).

For roof – if attic space is to be conditioned and there is no other provision for condensation control, I would start with two inches of closed cell directly to roof steel and then open cell to it to desired R value. If attic space is to be ventilated and insulation placed at ceiling level, if no condensation control do closed cell again, then blow in insulation at ceiling level. This will require adequate eave and ridge ventilation.

 

Spray Foam, “Rat Guard” Trim Cutting, and Ceiling Support Spans

This Monday the Pole Barn Guru takes reader questions about spray foam in an attic space, cutting “rat guard” trim, and ceiling joists for a 9′ span between trusses.

DEAR POLE BARN GURU: I am in the process of completing my Hansen building and decided to spray foam the roof and gable ends above the walls. When they came in to do the work I found they had foamed over the ridge vent closing it off. When I questioned this they said that is what you do when foaming the roof and the attic becomes a conditioned space. R14 on the roof does not sound sufficient. My floor is wood 4 feet off the ground. Is this right? Where should I go from here? Thanks ED in MYRTLE BEACH

DEAR ED: Provided you are including your building’s attic area in your conditioned space (not insulating directly above ceiling) then closing off your vented ridge would be correct. I have not been able to find anything printed to verify adequacy of R-14 for roof insulation with closed cell spray foam in Climate Zone 3 (South Carolina), indeed 2009’s IECC (International Energy Conservation Code) used by South Carolina would seem to lead one to believe ceilings require a minimum of R-30 (Please see Table 402.1.1 https://codes.iccsafe.org/content/IECC2009PDF/chapter-4-residential-energy-efficiency).

When you have an opportunity, please send back photos of your building, they would be greatly appreciated.

 

DEAR POLE BARN GURU: Hello there, for the life of me I cannot figure out how to cut the “Rat Guard trim” at the outside corner! At a 45 degree angle!!!! Please help!!!!! DANIEL in VANDERGRIFT


DEAR DANIEL: In my humble opinion, base trim should be mandatory for steel sided building panels. It keeps creepy, crawly critters from entering your building via open steel panel high ribs.


Direct from Hansen Pole Buildings’ Construction Manual, here are your instructions: https://www.hansenpolebuildings.com/2016/12/cut-install-base-trim-corner/

 

DEAR POLE BARN GURU: I have a 9 foot span between my trusses on my pole building and want to install steel on my ceiling. Do I need to install 2×4 braces between the trusses for additional support? I am planning on blowing in some insulation once the ceiling is installed. JASON in ROCKFORD

DEAR JASON: While I have heard of builders installing ceiling steel liner panels on trusses spaced even 12 feet apart without any additional support, my personal comfort zone is five feet – meaning, in your case, I would be adding 2×4 ceiling joists between my trusses. Make sure your trusses are designed for at least a three psf (pounds per square foot) ceiling load (truss drawings will show this as BCDL – bottom chord dead load) otherwise they will not be adequate to support weight of a steel ceiling.

 

 

Our Builder Has a Few Questions

Our Builder Has a Few Questions

Not a surprising statement, as few stick frame (stud wall) builders are willing to learn a new structural system, and few post frame builders have actually erected barndominiums or shouses (shop/houses).

I was a first group member (although willing to learn) and frankly lost my posterior financially erecting my first ‘pole barn’ because I had such a difficult time wrapping my head around left-to-right rather than up-and-down. I got my head on straight for building my second one and actually made $100 an hour back in 1980 erecting it!

For this second group, post frame home building takes in an entire new toolbox of concepts. Energy efficiency and ventilation concerns must be addressed, as well as a different set of efficiencies of material use. It is no longer just a ‘pole barn’  and requires a far greater degree of precision – it isn’t necessarily more difficult, but does take more thought.

Reader BRIAN in PETOSKEY writes:

Hi Mindi and Mike!

We’re really excited that we’re closing in on a final exterior design and starting to focus on the ‘fun stuff’ inside.

We shared the renderings and quote with our builder to keep him in the loop and he had some questions I wanted to share with you.

I’ve read your blogs and understand the argument for the truss arrangement that Hansen prefers. Trust me, I see the logic. That being said, he’s definitely one of those ‘trusses on 2′ centers’ kind of guys.

I explained all of the blog-based talking points on why it’s ‘better’. He was concerned that the material cost may be less, but the labor time would be significantly more to fill in between those spans with 2x10s, etc.

Furthermore, he usually covers the roof in OSB sheathing before putting on the metal. Is that included in this quote? Or is that something extra? He’s concerned about the logistics of applying the OSB with such wide spans between trusses. And in a similar vein, with drywall going on the full underside of all scissor trusses, he’s concerned about the additional lumber and labor needs to provide adequate hangers for sheetrock, etc.

And on top of that, he’s concerned about the lack of ventilation in the roof. I was under the impression that spray foam right onto the underside of the OSB for the entire roof was a best practice. He’s thinking we need baffles or something to allow airflow so as not to compromise the OSB over time.

So basically, a lot of questions on the construction logistics as it pertains to trusses and roof. Why not just run 31 scissor trusses on 24″ centers the length of the building and call it good? And how best to handle ventilation.

One comment he offered several times was that he understands the logic behind this construction style for a garage or storage building, but for a home with heat and sheetrock, etc. he thought this would be creating some obstacles for us.

If this is best answered via email, I’m happy to run middleman or add him as a CC on the answers. He also asked if Mike or someone from Hansen would be willing to talk to him on the phone? He’s open to the process, but wants to make sure he understands exactly what the construction process looks like. He said he would love to see a sample cross section or blueprint, but we both understand those are kept secret until we pay. He wants to wrap his head around it all.

One other concern was about wall framing. Some of the videos show horizontal studs as opposed to vertical. He wasn’t sure if that was always the case or if that is specific instances. Again, he’s a vertical stud kind of guy, but wants to understand if he can change that orientation or if it’s non-negotiable.

When it comes to truss space/between truss framing/wall framing, he’s definitely concerned about drywall logistics, OSB logistics (or not), moisture, and labor. And I want to make sure he feels heard and informed before we dump these plans and materials on his plate. I see both sides, but at the end of the day, he’s our builder and I need him to be fully on board before pulling the trigger. Could you help? I’m sure I’m not the first person with this quandary but I’ve also used enough pole barn builders in our area to know that he’s our best option for this project.

Thank you so much.

I see this dialogue as a parallel conversation to the design process. We’re forging ahead with design and working on our window and door placements this weekend.

Thank you!
Brian


Please tune in tomorrow for answers to Brian’s builder’s questions.

Insulation, Spray Foam Issues, and Floor Plans

Lets close out the week with a fifth installment of The Pole Barn Guru. Today he’ll answer questions about the best insulation for a building with steel roofing over a vapor barrier over plywood, potential issues installing spray foam, and a request for a floor plan example– we now have a third party provider of interior floor plans!

DEAR POLE BARN GURU: My barn has metal roofing over a vapor barrier over plywood. How can I best insulate the ceiling if I want to keep the slope and not enclose it into an attic space? DARCY in TURNER

DEAR DARCY: Closed cell spray foam insulation between your purlins is really your only choice, as any other method requires venting from eave to ridge above the insulation layer. You can expect somewhere close to R-7 per inch. First inch should be roughly $1.30 per square foot, with 70 cents per square foot for each additional inch.

 

DEAR POLE BARN GURU: I am thinking of spray foaming my steel pole building, have you heard of any issues? Thanks TOM in LINO LAKES

DEAR TOM: In a not too long ago addition to our home, as well as Hansen Pole Buildings’ Productions Building warehouse, we applied closed cell spray foam directly to steel panels with excellent results. You can read more here: https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/. You do have to protect interior spray foam surfaces from flame and make sure your installer is experienced and well trained to avoid potential issues with stink from a poor installation.

 

DEAR POLE BARN GURU: Do you have a floor plan example for model #08-0602 LORRIE in CLARKSDALE

Prefab pole barn cabin

DEAR LORRIE: We provide only the structural portion of most of our buildings, so do not have a floor plan for this particular building. You can have a floor plan custom designed for this particular building while best fitting your wants and needs via this link:  http://www.hansenpolebuildings.com/post-frame-floor-plans/?fbclid=IwAR2ta5IFSxrltv5eAyBVmg-JUsoPfy9hbWtP86svOTPfG1q5pGmfhA7yd5Q

 

Bolt to Slab, Metal Distortion, and a Moisture Drip Issue

This week the Pole Barn Guru answers questions about use of dry-set brackets to existing slab, spray foam distorting metal, and a problem with drip when temperature is just right.

DEAR POLE BARN GURU: How thick does the edge of concrete need to be to support a pole barn if using the bolt on top of existing slab? CHRIS

DEAR CHRIS: Our independent third party engineers have determined brackets dry mounted to existing concrete slabs are not a good structural solution and will no longer certify such connections. We would recommend either saw cutting holes in your slab to use either embedded or wet set bracket mounted columns, or to place columns around your slab’s perimeter.

 

DEAR POLE BARN GURU: Why does the spray foam distort the metal? LARRY in KALISPELL

DEAR LARRY: Properly installed closed cell spray foam insulation should not distort either roof or wall steel. My lovely bride and I used it when we added an elevator shaft on the rear endwall of our shouse and it was used to insulate a recent approximately 3000 square foot addition to Hansen Pole Buildings’ warehouse. Both were done with no noticeable steel deflection. Here is some further reading on this subject https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/.

 

DEAR POLE BARN GURU: We have a moisture problem in our 36×45 pole barn when the weather is right it drips when the sun warms it up. I understand I need more ventilation. Along the top center ridge there is formed foam gasketing like you have talked about. Some of it is falling out. Can I remove that to improve ventilation or is that there to stop rain or snow from coming in? Really appreciate many of the tips you have on your site. RON in MAZOMANIE

DEAR RON: I will suspect your dripping issue is due to there being no thermal break between your building’s roof framing and roof steel. If this is your circumstance, your only real solution is to have two inches of closed cell spray foam applied to inside of your roofing. While adding ventilation may remediate some of your challenge, there is still going to be some degree of warm moist air trapped inside.

In order to adequately ventilate, you will need to have both an air intake and an exhaust. You could remove your ridge cap and replace your present formed ridge closures with a similar vented material (vented closures). For air intakes, if your building does not have vented sidewall overhangs, you could add gable vents at each end.

 

Slab or Crawl, Insulation, and Building by a Leach Field

This Monday the Pole Barn Guru answers reader questions about building on a slab or with a crawl space, insulation for a shop, and if a person is able to build near a leach field.

DEAR POLE BARN GURU: I appreciate the building technology used when building a residential pole barn. I am not yet convinced about a slab floor. Although radiant heat is a plus I have two concerns. 1st I’m not sure of the impact when walking on concrete and what is done about air conditioning the building. Have you seen pole framing on a stem wall crawl space deck. Thanks. JOHN in SUMMERSVILLE

DEAR JOHN: Although our own shouse has geothermal radiant floor heating and cooling (https://www.hansenpolebuildings.com/2016/12/modern-post-frame-buildings-geothermal/) I tend to agree with you about what surface I would like to live upon. If I had to stand on concrete for very long, my knees would be screaming at me. We have provided many post frame buildings built over crawl spaces, with most using embedded columns and attaching raised wood floor supports to them. This is far more cost effective than pouring a stemwall (we have had clients go this route as well). For extended reading please see https://www.hansenpolebuildings.com/2019/03/slab-on-grade-or-crawl-space/.

DEAR POLE BARN GURU: I’m working with Greg Lovell on a building design. Pole barn 30 x 48 x 10 will be walled of to two 24 X 30 shop areas.

My question is on insulation, I’ve read you recommend a ceiling and insulating above that with a vented ridge.

So… if this is not going to be a building I heat 24/7 and never cool. Can I get by with reflectix under the metal roofing and insulating between the purlins with unfaced insulation, if I’m only going to heat it when I’m in it during the winter (heat with a wood stove).

Your post says if I do it this way I need to construct an air gap between the purlins and the roofing material, given the above scenario do I need this air gap if I only heat it a few times a week during the day? Obviously if I do need the air gap the ceiling would be a better way to go. LEE in IDAHO FALLS

DEAR LEE: Code does require airflow above insulation from eave to ridge with this scenario. An option might be to use two inches of closed cell spray foam insulation applied directly to roof steel underside. This would eliminate a need for a Reflective Radiant Barrier as well as ventilation above it. Closed cell spray foam should run roughly two dollars per square foot of roof surface and provide about R-13.

Advantage of a ceiling with insulation blown in is you only heat area below ceiling. Should you or some future user decide to climate control, this would provide a big start.

 

DEAR POLE BARN GURU: Can you build a pole barn at the bottom of a leach field? TRACE in JAMUL

DEAR TRACE: Yes you can. Typically most jurisdictions require any non-full foundation buildings to be at least 10 feet from any leach line. Consult with your local Health Department for requirements for your jurisdiction.

 

 

 

 

A Garage Apartment, A Moisture Problem, and Insulating a Ceiling

Today’s Pole Barn Guru answers questions about building a garage apartment aka a “Shouse,” how to address a moisture problem, and the best way to add insulation to a ceiling.

DEAR POLE BARN GURU: Can I design a garage apartment pole barn? JAY in HINTSVILLE

DEAR JAY: You may not have this ability however we have experts who can assist you. To develop a workable custom floor plan, designed specifically to meet your wants, needs and budget please use this link: http://www.hansenpolebuildings.com/post-frame-floor-plans/?fbclid=IwAR2ta5IFSxrltv5eAyBVmg-JUsoPfy9hbWtP86svOTPfG1q5pGmfhA7yd5Q

 

DEAR POLE BARN GURU: Live in the Midwest, have a 54 x 36 pole barn well insulated, walls, and ceilings. When it rains a lot I have a moisture problem, My building is approx. 1950 Sq. Ft. I found a dehumidifier that covers 3,000 sq. ft. I was thinking about putting one in the pole barn, it can run continuous if I put a hole in the side, for a drain, and let it drain out, just leave it running on its own as it needs to. Is this Ok to do to solve my issue? RON

DEAR RON: A dehumidifier may resolve your building’s symptoms, however not its problem. As this is a function of rain, I am led to believe you need to eliminate or reduce your moisture source. If your building does not have a vapor barrier under your concrete floor, seal top of floor. If you do not have rain gutters install them and ensure runoff is directed well away from building. Make sure ground outside of building is sloped away at least 5% for 10 or more feet.

 

DEAR POLE BARN GURU: I have a 32X46X15 pole barn with purlins attached to the outside of the 6×6 beams. The barn has soffits and a vented ridge cap and is set up for a ceiling. I have since decided to keep the rafters exposed and have questions about sealing up the soffits and ridge cap but leaving several small openings in the ridge cap to allow for humidity to escape.

How much should I leave open on the ridge cap and should I totally seal off the soffits? Will it be ok to leave the beans and rafters exposed, putting a vapor barrier in between the beams and the rafters?

What are your thoughts on 2in foam with no vapor barrier glued directly to the metal in between the purlins every 2feet? Then another 2in foam board with a vapor barrier placed on top of that screwed to purlins and can spray foam the edges and gaps? Thanks for all your help! MARK in VALPARAISO

DEAR MARK: My response is with a thought you are trying to climate control your building to some extent. Your proposal to use two inch-thick foam insulation board sounds to be highly labor intensive as well as being fraught with challenges in trying to achieve a complete air seal. Any air gaps would allow for warm moist air from within your building to not only condense against your building’s steel cladding, but also to remain trapped there, potentially being a cause of premature degradation of steel panels.

I would recommend you look towards closed cell spray foam as a solution for both insulation as well as condensation control. You will want to completely seal both eave and ridge then have at least a two inch thick layer of closed cell foam sprayed on interior face of roofing and siding. A mechanical dehumidifier should be used to control relative humidity with your building.

 

 

 

 

Pylon Sizes, Insulating a Pole Barn, and Plastic for Drainage

This week the Pole Barn Guru answers reader questions about concrete pylon sizes, how to best finish and insulate an existing structure, and the best plastic for drainage.

DEAR POLE BARN GURU: What size do the concrete pylons need to be for a 24×36 building with an 11’ roof peak to be used for storage. No footer, just the basic building with 6”x6” posts. JAMES in VERSAILLES

DEAR JAMES: This information should have been clearly indicated on engineer sealed plans you are using for construction. Actual required depth, diameter and amount of concrete required to prevent settling, uplift and overturning is carefully calculated by your building’s engineer, once all factors can be considered. These include, but are not limited to: soil strength at your site, building wall height, roof slope, weight of building itself, snow load, wind speed and wind exposure, seismic considerations, whether building is fully or partially enclosed or is ‘open’, as well as spacing of columns. In most cases, I would expect to see an engineered design of roughly 40 inches in depth, 18 inches in diameter, with a minimum of 18 inches depth of concrete in bottom of hole (a bottom collar) and base of column held up eight inches from bottom of hole. A steel uplift plate is typically placed on columns in concreted area to prevent uplift. All of these factors as well as typical suggestions above should be fully reviewed and sealed by your building’s engineer prior to your moving forward.

 

DEAR POLE BARN GURU: I’ve been reading through Mike’s information regarding post frame construction.

My wife and I moved into my parent’s old house, and would like to finish the inside of the pole barn that my father built 4 years ago. The trusses have a BCLL of 10 lbs. There’s single bubble between the purlins and metal, so the underside of the roof is always dry. We’d like to insulate the barn, but there is no housewrap (Tyvek) on the walls. My wife works and I’m disabled, so we don’t have very much extra money to spend. I’m physically not able to remove the metal on the walls and install housewrap. We can’t afford to hire someone to do this. We also can’t afford to have an insulation company spray foam the walls which would solve our problem. My father left about 60 new sheets of EPS foam board, and 50 – 60 new rolls of unfaced fiberglass insulation in the barn. Instead of taking the metal off the walls, would it be possible to wrap the interior of the walls in housewrap? It would be on the inside of the wall girts and wrap around the inside of the post. Would this prevent condensation from forming in the walls? Would it do any good to cut the EPS foam board and put it between the wall girts and fill all the edges of the EPS board with spray foam? I’m trying to come up with a practical solution to the problem, and was hoping Mike could help. I don’t want to ruin the fiberglass insulation, or the EPS foam board. I read one of Mike’s post about his wife being in a motorcycle accident and is now a paraplegic. I was driving home from work 19 years ago, and a big truck hit my car in the driver’s door. I was lucky to survive and was in a wheelchair for over 10 years. I still have the desire to do stuff out in the garage, but am very limited to what I can actually do. You never know what your future holds. Let me know if Mike has any possible solutions. I would appreciate it. GREG

DEAR GREG: Thank you very much for being a loyal reader.

Best possible solution would be to resell the EPS and the fiberglass and put those funds towards two inches of closed cell spray foam.

Trying to cut foam board and completely air seal it would be lots of labor and impossible to achieve. A Weather Resistant Barrier (Tyvek or similar) on the inside of the wall would either trap moisture in the wall or have it passing through into your interior without solving condensation against your wall steel. Chances are you would end up with some damp fiberglass over time.

 

DEAR POLE BARN GURU: I am considering using 6 mil plastic sheeting about 5 feet wide from the bottom of the outside wall to drain any rainwater away from the building.  Do you know of any issues this might present? RON in WINSTON

DEAR RON: If I was going to do this I would use 15mil black plastic as 6mil will just not hold up over time. I would seal it to my building’s pressure preservative treated splash plank and make sure to have ground sloping away from my building beneath plastic minimum of 5% (three inches in five feet).

 

Flash and Batt Insulating Barndominium Walls

Flash-and-Batt Insulating Barndominium Walls

We’re in a seemingly never ending cycle of racing towards net zero post frame homes, shouses (shop/houses) and barndominiums (read more on net zero post frame here: https://www.hansenpolebuildings.com/2019/01/net-zero-post-frame-homes/). 

One possible design solution involves what is known as “flash-and-batt” where two inches of closed cell spray foam insulation is applied to steel siding interior surface between barn style wall girts, then balance of insulation cavity is fitted with fiberglass batts.

Today’s expert opinion is rendered by Martin Holladay, former editor of the Green Building Advisor web site. You can read more about Martin at www.MartinHolladay.com.

Even though thicker is always better with any type of insulation, applying a thin layer of spray foam is a good way to get air-sealing benefits at considerable cost savings over full-thickness spray foam.

Some spray-foam contractors dismissively call the technique “flash-and-dash”; they point out that fiberglass batts may fail to remain in contact with the spray foam, creating an air space and the potential for convective air currents through the insulation. But I think this is a relatively insignificant problem, particularly if the cavity is fairly airtight. Besides, it’s easy to minimize the chance of a potential air space by simply choosing a thicker batt. In fact, batts that are compressed slightly as they are installed will yield higher R-values than ones that just fill the cavity.

Another concern is that in a heating climate, the flash-and-batt method creates a vapor retarder on the wrong side (the cold-in-winter side) of the fiberglass batt. But whether the spray foam actually becomes a vapor retarder depends on the type of foam used. Open-cell foams — that is, foams with a density of about 1/2 pound per cubic foot — are very vapor-permeable. However, since many low-density-foam manufacturers, including Icynene, recommend against the flash-and-batt method, most proponents use closed-cell foam with a density of about 2 pounds per cubic foot.

One inch of closed-cell foam has a permeance of about 2 perms, while 2 inches has a permeance of about 1.2 perms, so closed-cell foams are effective vapor retarders.

But does installing a vapor retarder on the cold-in-winter side of a wall create a problem? Actually, research has shown that exterior foam can safely be used as part of a cold-climate wall or roof — as long as the foam is thick enough. As a rule of thumb, walls with exterior foam sheathing or flash-and-batt closed-cell foam will avoid condensation problems as long as the foam is at least 1 inch thick in climate zone 5 (Pennsylvania, Iowa, Nevada) or 2 inches thick in climate zone 7 (northern Minnesota).

Since exterior foam reduces a wall’s ability to dry to the exterior, it’s important to choose an interior vapor retarder that allows drying to the interior — such as kraft-paper facing or vapor-retarder paint — instead of sheet poly.

Roof Trusses 4′ o.c., Condensation Issues, and a Sliding Door

This Monday the Pole Barn Guru answers questions about roof trusses at 4′ o.c., ways to solve condensation issues, and sliding door options.

DEAR POLE BARN GURU: My question is I just purchased some roof trusses that are 32 feet long heel to heel they are constructed with 2 by 4s can I put these on 4 foot centers? Thanks. CRAIG in BELVIDERE

DEAR CRAIG: You can if you want your building to collapse in a moderate snow event. Along with your trusses, you should have received an engineer sealed truss drawing with all specifics as to what can be carried by it and spacing. If you did not, and they are prefabricated metal connector plated wood trusses, there should be a manufacturer’s stamp somewhere on truss bottom chords. You could then contact them and give them truss specifics (and probably a few photos showing lumber grades, web configuration and steel connector plate sizes. From this, they may be able to determine what you have actually spent your hard earned money on.

If you are unable to determine where they came from, another alternative would be to take their information to a Registered Professional Engineer with roof truss experience. For a few hundred dollars, you may be able to get an opinion as to their strength.

 

DEAR POLE BARN GURU: Hello, I have a 30x46x16 all steel pole barn that I am having condensation problems with. My question is what is the best thing I can install or do to help the problem? I have been told by others to install a ventilation exhaust fan controlled by an thermostat. I do have electricity in barn. I also have a wind turbine I haven’t installed yet too? Should I put both of these items in or one of them? And if so, do you guys install these items? Please help, its rusting all my tools and growing mildew in my RV!! Thanks ALYSSA in LEWIS CENTER

DEAR ALYSSA: You have found a challenge (one of many actually) Quonset steel building providers never seem to mention – condensation (read about other Quonset issues here: https://www.hansenpolebuildings.com/2011/07/quonset-huts/).

The two best things you can do are to seal your concrete floor (https://www.hansenpolebuildings.com/2019/02/how-to-properly-apply-post-frame-concrete-sealant/) and have two or more inches of closed cell spray foam insulation applied to the inside of your steel building shell. An exhaust fan might help, provided it can adequately move enough air (need to move between 3000 and 4000 CFM – cubic feet per minute) and it will require an air inlet of similar dimensions. We are not contractors, so we won’t be able to assist you with any installations.

 

Figure 27-5

DEAR POLE BARN GURU: Hi. Not really looking for a whole building. What I am looking for is an exterior sliding door to install onto a shop wall. The Shop is a timber frame unit. The opening is roughly 6 feet wide by 7 – 7.5 feet tall. I have not yet taken exact measurements. I will as soon as I can find a vendor within my price range.

I was very intrigued by your video presentation describing the “nail on” round track system. Also, this shop is in an odd location. It is a basement shop under my house, the house is built on a slope, so the wall I want to put the door onto is at ground level, but the opposite wall is fully underground. Since it is an exterior door to my basement any info on weather sealing for the cold Vt. Winters would be greatly appreciated. ANDREW in WESTMINSTER

DEAR ANDREW: Whilst I can appreciate you thinking a sliding “barn style” door might be a solution, I am doubtful as to it truly being a viable design solution. At best a sliding door will be a challenge to insulate beyond a bare minimal R value. A bigger concern is you are not going to achieve a tight air seal.

A design solution I can recommend (although it may stretch your budget) would be to go with an insulated commercial steel double entry door (six feet wide) in steel jambs. These doors will afford a secure access to your shop, are insulated and can seal air tight.

Although we typically only provide doors with our complete third-party engineered post frame building kit packages, you can message Materials@HansenPoleBuildings.com for a delivered price.

 

A Post Frame Addition, California Muster, and Ventilation

Today the Pole Barn Guru answers questions regarding a post frame addition, passing the “muster” of California’s building codes, and ventilation of attic space with spray foam.

DEAR POLE BARN GURU: Hi. We are wanting to attach a monitor style barn to an existing stick build for additional residential use. Is this tie-in possible? Thank you! TOM in KIRTLAND

DEAR TOM: It is very possible and will quite probably provide some real advantages, besides just affordability. Post frame buildings can be any variety of sidings, so it should be able to be structurally designed to tie pretty much up to any type of exiting building – provided existing building is structurally sound.

In order to do this right you have only a couple of choices – you can spend a lot of money on an architect and/or engineer who physically comes to your site (could be as high as 20% of project’s finished costs). Or you can provide lots of information to us on what we are attaching to, as well as conveying your expectations. We will do anything reasonable to assist you in not making a mistake you will regret always. If I thought anyone else could not just actually do it but also do it better than us, with you being able to construct yourself, I would in all honesty let you know.

Please dial 1(866)200-9657 and speak with a Hansen Pole Buildings’ Designer who can assist you to success.

 

DEAR POLE BARN GURU: Hi, Do you have any residential structures that have recently passed muster in southern California?

FYI I have a lot in Malibu but little $. I am wondering if I – and usually one helper – could construct a fire resistant home in this picky building code state.

Thanks, DAN in LOS ANGELES

DEAR DAN: We’ve been providing post frame building kits in Southern California areas of Very High Fire Hazard Severity Zones as well as Wildland-Urban Interface Fire Areas for years. Is does take a certain amount of patience, as plans almost always get kicked back at least once (relax – it is just a part of this process). Using steel roofing and siding, unvented steel soffits and wrapping any wood normally exposed with steel trims expedites approvals. If your property is located in a HOA (https://www.hansenpolebuildings.com/2012/11/homeowners-association/) be certain to talk with them sooner, rather than later.

As far as you and a helper – as long as you can and will read instructions and look at our third-party engineer’s highly detailed plans you should experience no real challenges. And, if you get stuck, we provide unlimited Technical Support at no extra charge.

A Hansen Pole Buildings’ Designer will be reaching out to you for more in depth discussions.

 

DEAR POLE BARN GURU: We bought a house kit from you all and have been very pleased. We had the roof deck, exterior walls and exterior walls of the crawl space spray foam insulated. They have essentially sealed the house. Will the lack of attic ventilation be an issue? HOLLY in TAYLORSVILLE

DEAR HOLLY: Thank you for your kind words, we would enjoy seeing any digital photos or video of your building during construction as well as completed.

If you spray foamed roof deck and have a dead attic space due to a flat level ceiling (we provided ceiling loaded trusses as well as ceiling joists) then you could experience condensation issues and potentially mold and/or mildew in attic, especially if attic is not made part of conditioned space (heated and/or cooled) with living area. If flat ceiling has also been insulated look out for trouble (keep a close eye on situation by doing visual attic inspections), as attic space could become quite a bit cooler than area below ceiling. Your spray foam contractor should have been talking with you about this prior to doing his or her application.

 

Minimizing Post Frame Ice Dams

Minimizing post frame ice dams

November 1996 in Northern Idaho will probably forever be known as “Ice Storm”.  About six weeks prior to this event, my construction company had completed a post frame building just south of Sandpoint. When massive snow and ice storms hit, our client kept his new building warm by use of a wood stove. Heat from wood stove melted accumulated roof snow and ice. This snowmelt then proceeded to freeze along his building overhangs, forming ice dams.

Solid ice weighs roughly 57 psf (pounds per square foot). When our client’s roof ice buildup got to be over two feet thick, they caused a roof collapse – probably no surprise being as this weight was almost triple the building’s design roof load!

In cold climates getting a lot of snow, heat from inside a post frame building escaping into a traditional attic can warm the roof. Combine this with rooftop snow load insulating from cold exterior temperatures and roof deck can increase in temperature above freezing. When this happens, the bottom layer of snow can melt, and the resulting water will run down the roofline to roof’s edge.

If this occurs while average exterior temperatures are still below freezing, perimeter overhangs will likely be below freezing, and this liquid water can freeze near a roof’s perimeter – leading to icicles and possible ice dams.

You are probably familiar with icicles, but an ice dam occurs when a ridge of ice forms near roof edges and prevents melting snow/water from draining off the roof. Ice dams will grow as more water flows down the roof, builds up behind ice and freezes, However ice will only form when roof portions are below freezing temperatures, so as snow melts, liquid water will collect behind ice. When this water finds small cracks, crevices and openings in roofing it can flow into the building, causing damage.

Ice dams can break gutters, lift roofing and can cause water to back up and leak into pole buildings. Of course when water gets into a building, real damage occurs – wet insulation, peeling paint, warped wood, stained and sagging ceilings and more.

How do we solve ice dam problems?

A short-term fix – remove snow from the roof, such as by sweeping it off or using a “roof rake”, because no snow means no melt, so there will be no eave ice buildup. And for long-term solutions there are some mechanical options, like heat strips (https://www.hansenpolebuildings.com/2013/04/hotedge/), and there are some sound building design principles helping to lower ice dam risk.

Ice dams occur because of uneven roof deck temperatures, so the key principle in lowering ice dam risk will be to maintain more consistent roof deck temperatures. This can be done by reducing heat loss from conditioned space to attic and thereby keeping heat away from roof underside.

In practice this means reducing air leakage, increasing attic insulation value and verifying good natural roof ventilation, when applicable.

There are a couple of ways use of spray foam insulation can help mitigate ice dam risk in cold climates.

Spray foam attic floor, providing an air seal across ceiling, reducing air leakage from conditioned space to attic, and we can put in as much insulation value as desired, either with all spray foam or a hybrid system incorporating spray foam with blown in insulation above. With a vented system like this, we also want to make sure we have good natural ventilation through soffits, eaves, gables, ridges, etc. This design combines all key design principles to reduce ice damming risks.

Spray foaming underside of roof deck moves thermal boundary and air barrier to underside of roof deck. It means attic space resides inside building thermal envelope and creates a sealed, unvented attic. In this design, key plane of protection becomes spray foam layer under roof deck, protecting the roof deck from interior heat and attic air. The roof deck will now be primarily exposed to exterior conditions and more likely to remain cold.

Crawlspace Skirting, Adding Spray Foam, and Rafters

Today the Pole barn Guru discusses crawlspace skirting, adding spray foam, and building with rafters instead of trusses.

DEAR POLE BARN GURU: I am planning on building a post frame home with a standard wood framed floor structure. It will have a crawlspace below but will not have concrete stem walls. The building site slopes down, some of the crawlspace may be excavated below grade, some areas will be above grade. Looking for ideas for skirting the crawlspace to provide the most appealing look at exterior side and keep out water and pests. TRENT in WALLA WALLA

DEAR TRENT: In areas where your building’s crawl space would involve excavation below grade, it might behoove you to place a permanent wood foundation between columns (https://www.awc.org/codes-standards/publications/pwf-2015).  In other areas most of our clients have run steel siding down to four inches above grade, just like typical post frame construction.

DEAR POLE BARN GURU: Looking to spray foam the Hansen pole barn we built.

I have some questions.  We ordered the kit with roof insulation and it was installed when built. I’m thinking of leaving the ceiling open so the trusses are exposed. Can the foam be sprayed over the insulation? If the insulation is removed can the foam be sprayed directly to the roof? If so do I just close off the ridge vent? On the side walls do I just close off the top that opens to the eaves? MARK in MT. AIRY

DEAR MARK: Make sure to use only closed cell spray foam. I have heard arguments both for and against using spray foam against either a weather resistant barrier (such as Tyvek) in walls or a reflective radiant barrier. For this one I would defer to an answer from whomever will be doing your foam application, since they will have to warranty their installation. Certainly you can spray foam directly to inside of steel panels – I did this in a recent addition to my own post frame building home. You will need to close off both vented ridge as well as soffit.

DEAR POLE BARN GURU: Is it possible to build a pole building roof structure with rafters rather than trusses? FRED in GREENBANK

DEAR FRED: As long as building can have either interior columns, or single sloped (within reasonable span limits) it can certainly be raftered, rather than trussed. Please see this prior article in regards to pole and raftered buildings: https://www.hansenpolebuildings.com/2012/08/stall-barn/

 

Building Height, Building on Existing Foundation, and Spray Foam

Today the Pole Barn Guru answers questions about calculating the height of a building, Building on and existing foundation, and Spray Foam Insulation.

DEAR POLE BARN GURU: I’m looking for over all height of a building with a 14’ eave?
Thanks. DOUG in PILOT ROCK

DEAR DOUG: The overall height determination starts with a clear understanding of how eave height is to be measured: https://www.hansenpolebuildings.com/2015/02/eave-height-2/.


 

With this in mind, the rise of the roof can be calculated by multiplying the distance from sidewall building line to the center of the building, in feet and multiplying this by the roof slope. Here is an example for a 36 foot width gabled roof with a 4/12 roof slope:  36′ X 1/2 (half the building width) X 4″ / 12″ = 6 feet. Adding this to the eave height gives an overall height of 20 feet, in this particular example.

 

DEAR POLE BARN GURU: Can they be built on a poured basement wall from a previous home? PAT in GREENEVILLE

DEAR PAT: As long as the concrete is structurally sound you should be able to utilize dry set column bases (ones designed specifically for post frame construction) to mount columns to the top of the foundation.

 

DEAR POLE BARN GURU: I have an existing Hansen pole barn 24×24 with a 9ft eave height and full length ridge vent, it has reflective roll insulation between the roof panels and the purlins. How can I further insulate it from Florida heat? I insulated the walls with rigid insulation. Can I add insulation under the existing reflective insulation at the roof? STEVE in ROSELAND

DEAR STEVE: I’d be contacting local installers of closed cell spray foam insulation. You will get close to R-7 per inch of foam (again, must be closed cell) and do not have the ventilation issues posed by using batt insulation between purlins. You will need to block off the eave and ridge vents for this to be an effective solution.

 

 

 

 

Spray Foam, Up Instead of Out, and a B-Ball Court

Mike answers questions about spray foam releasing agents, Going up instead of out, and a Post Frame Basketball Court.

DEAR POLE BARN GURU: Thank you for this blog of informative words on the world of post frame construction. I am a confirmed fan of spray foam insulation. What are your thoughts on the use of a release agent when applying spray foam directly to metal, be it sidewalls and a conditioned attic? CHUCK in MERINO

DEAR CHUCK: Thank you for your kind words. I’ve become a closed cell spray foam convert over the past few years. I am seeing more and more practical applications for it as folks become more energy conscious about their post frame buildings.

Spray foam release agents are a blend of specialized parting agents, specifically designed to prevent polyurethane foam insulation from adhering to most surfaces where the product is applied.

I am far from an expert on spray foam, so I’ll have to go with the common sense answer of I want the closed cell insulation to stick. I suppose it might work on sidewalls, with the idea of perhaps wanting to replace a damaged steel panel someday – provided the insulation remained rigid enough between the wall girts to stay in place. Below roof steel, I would have some concerns about the force of gravity causing it to drop off the roof. It could also lead to a gap where moisture could collect (especially if a roof leak occurs).

 

DEAR POLE BARN GURU: Curiously. I’m wanting to build post frame. I know the rule of thumb is if you have the space to build bigger on the ground before going up, but my lot is limited to only 1/4 of an acre, and strict building codes only allow so much square footage to be taken up but doesn’t go against additional levels only ground floors and basements.  So my question is: Will post frame structure support a second level, and also attic trusses for a future room later down the road? Can I even buy a kit like this? JESSE in LEESBURG

DEAR JESSE: It is always most affordable to build the largest footprint one can, on a single level. It also is most practical in terms of accessibility. Even for those who are not mobility challenged, going up and down stairs gets to be old far before we are!

You can have a post frame building designed to support both a second floor and even a third if so desired. And attic bonus trusses can be incorporated into the design. Make sure to be talking with your local Planning Department, as they often have rules which may restrict heights. The building height can also affect setbacks from property lines and other structures as well.

DEAR POLE BARN GURU: We are considering a pole barn construction for a community recreation center which would include a basketball court. We want to have second story six foot wide walking track around the interior of the building. Do you have thoughts regarding the difficulty of doing the track? BILL in ALBION

DEAR BILL: Post frame construction is most certainly the way to go for basketball courts (read more here: https://www.hansenpolebuildings.com/2017/04/indoor-basketball-courts/). Having a mezzanine walking track is most certainly doable by utilization of prefabricated metal connector plated truss frames which could be connected to the sidewall columns and cantilever over the court area below. Joists can them be placed between the frames, with ¾” thick OSB or plywood on top, then your choice of floor coverings (rubberized floor matting might be an idea).

The design should incorporate some fairly significant deflection limitations, so as not to feel bouncy to those who are utilizing the space.

The track should also be placed fairly high on the walls, so the thickness of the frames does not interfere with activities below.

 

 

 

Spray Foam Insulation: What’s the Stink?

What’s the Stink?

One popular, although expensive, method of insulating pole buildings is with spray foam insulation. Besides cost, spray foam can also bring with it problems in the form of lingering odors.  These odors are coming from a catalyst in the foam, or from foam which is off-ratio, not mixed well or sprayed too thickly.

Odors which might occur with the foam application are typically caused by either the contractor applying the foam in greater than a 2-inch pass, or applying a second pass over the first without allowing the first pass to dissipate the heat and properly cure.

The odor occurs when the foam is slightly under processed. It happens when the recommended application temperatures aren’t followed. The recommended temperature varies with the substrate and weather conditions. As an example if the recommended application temperature is 140 degrees, and spray is done at 125 degrees, a full reaction does not occur. (These are the temperatures of the product leaving the gun). In this case, the amine catalyst (which has a strong odor) does not react properly and it won’t be fully consumed. It is real stinky.

A spray foam insulation work site should be isolated with polyethylene barriers and depressurized with an exhaust fan while the foam is being sprayed.

Some believe smelly foam problems can be solved by heat and ventilating the smelly areas. Most experts advise the only way to solve these problems is to remove the bad foam from the pole building.

Even foam removal may not solve a problem with a persistent odor, however as it is thought the smell can migrate to the framing lumber.

Thinking of hiring a spray foam contractor to insulate your pole building? Find out as much as possible about their training, their certification, and their experience level. In addition to verifying the training credentials of your spray foam contractor, you should insist your contractor isolate the work area and set up a fan to depressurize the areas where foam is being sprayed.

The industry has an almost impossible problem inherent in their dependence on spray contractors who have to comply fully with all installation instructions each and every time. For instance, they may have to spray to a certain thickness, wait, and continue spraying. Contractors may or may not follow such instructions to the letter. The industry’s own guidelines call for exhaust ventilation, but this practice is widely ignored. The point is, if the spray contractors truly had to work within all manufacturer instructions and industry guidelines, it would up-price the job.

Any experienced pole building package supplier knows building materials are occasionally defective. When a damaged or defective component is on the job site, the supplier wants to be able to call up a manufacturer’s rep and have the problem resolved quickly. If this happens, the supplier becomes a loyal customer. In fact, most suppliers’ choice of door brand is based not on the door quality but on the service provided by their rep. By this standard, many spray foam insulation manufacturers are failing dismally, as the service is often less than exemplary.

The advice to spray-foam manufacturers is simple: it’s not acceptable to brush off customers with smelly foam. If these cases aren’t quickly resolved, the dead-fish smell is likely to taint the entire industry.