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How to Properly Insulate between Roof Purlins

How to Properly Insulate Between Roof Purlins

Efficient climate control is becoming the buzz term for post frame construction. A challenge occurs when clients look to insulate between their roof purlins.

Reader JOHN in COVINGTON writes:

“I am building an all wood pole building. The purlins are 2x8s. I want to insulate the walls and up at the purlins to keep as much usable space as possible with an insulated building. How do I insulate and properly vent between the insulation and the underside of the plywood roof underlayment. If I use R19 it is 6 inches so there would be 2 inches of space between the insulation and the wood. Do I use something like a house bird block at each end of the building for each purlin space?”

Mike the Pole Barn Guru Writes:

The best solution lies in creating an unvented roof

It is quite possible to design an unvented insulated roof assembly which performs well, as long as you get the details right. In recent years, most building codes have begun to allow the construction of unvented insulated sloped roof assemblies. Many such roofs have failed over the years, however, so don’t get creative. Follow the rules.

For sake of brevity, I will limit this discussion to only as it pertains to post frame buildings with widely spaced trusses and purlins on edge.

First of all, you can’t use air-permeable insulation (for example, fiberglass batts, mineral wool batts, dense-packed cellulose, or blown-in fiberglass) to insulate an unvented roof assembly unless the roof assembly also includes a layer of air-impermeable insulation (spray polyurethane foam) directly below the roof steel or sheathing.

The 2009 IRC (International Residential Code) defines air-impermeable insulation as “an insulation having an air permeance equal to or less than 0.02 L/s-m² at 75 Pa pressure differential tested according to ASTM E 2178 or E 283.” Although spray foam insulation and rigid foam insulation meet this standard, fiberglass batts and dense-packed cellulose do not.

If you want to use just one type of insulation in unvented bays, you are limited to spray polyurethane foam. Another possibility, of course, is to build your roof with structural insulated panels (SIPs), which in most cases is cost prohibitive.

The code restrictions on the use of air-permeable insulation between purlins were developed to prevent the purlins or roof sheathing from rotting. When fiberglass batts are installed in unvented bays, the batts allow moist indoor air to reach the cold steel roofing or sheathing. That leads to condensation or moisture accumulation, followed eventually by rot. Since spray foam prevents air movement, it almost eliminates this problem.

It’s important to note, however, recent research suggests closed-cell spray foam is much less risky than open-cell spray foam in this location.

To summarize, there are really two practical ways to build an unvented roof assembly:

Install closed-cell spray foam against the underside of the steel roofing or roof sheathing, and no other type of insulation. Be sure the thickness of the spray foam is adequate to meet minimum code requirements. Remember open-cell spray foam is risky in all climate zones, and if open-cell spray foam is installed in this location in a cold climate, the underside of the cured foam must be covered with gypsum drywall which has been painted with vapor-retarder paint. Vapor-retarder paint is ineffective if it is sprayed directly on the cured foam.

Install a layer of closed-cell spray foam against the underside of the steel roofing or roof sheathing, and fill the rest of the purlin cavity with an air-permeable insulation. This type of assembly is designed to dry to the interior, so the assembly should never include an interior polyethylene vapor barrier.

 

 

This entry was posted in Insulation, Pole Barn Questions, Roofing Materials, Pole Building How To Guides, Ventilation and tagged , , , , on by .

Adding Insulation, Financing, and Adding a Ceiling

This Wednesday the Pole Barn Guru answers reader questions about options for insulation of an existing steel building, financing options for a post frame home, and adding a ceiling to an existing barn.

DEAR POLE BARN GURU: I have a preexisting steel building with no insulation. I am looking for affordable methods to insulate the building in our climate. There are swings in humidity and temperature as well as a fairly long winter. The tin is attached to Perkins that are 24′ on center. The distance between the red structural frame varies from almost 7′ to 10′ PETER in MINNEAPOLIS

DEAR PETER: You really only have two realistic options and both involve closed cell spray foam.

Your building is in Climate Zone 6. In order to prevent condensation, 35% or more of your insulation should be closed cell spray foam applied directly to steel siding and roofing. You can go all closed cell, however your will find this to be painfully expensive. By using spray foam against the steel, then filling your cavity with Rockwool batts, you can reduce costs without compromising performance.

For your roof R-60, this could be done with 3″ of closed cell plus R-39 of batts. Walls, you could go R-20 (basically 3″) of closed cell and be done with it. For mixed systems, you can do R-10 of closed cell (1-1/2″) along with R-15 batts.

You should also plan upon having to mechanically dehumidify your space.

 

DEAR POLE BARN GURU: Hello. Looking to build a barndo home in north Georgia. I’m looking for financing the structure. Do you guys offer financing at Hansen? If so, does this include the concrete pad/foundation? Thank you for your time! BRIANNA in DALTON

DEAR BRIANNA: Thank you for your interest in a new Hansen Pole Building. In answer to your questions – yes we have financing available and it can be used for more than just what we provide. www.HansenPoleBuildings.com/financing/

 

Installing a ceilingDEAR POLE BARN GURU: Have a 40×60 barn trusses have 2×8 top and bottom chord set on 10 ft centers live I deep so Illinois. Question is how is best way to frame in ceiling to put up metal might put small amount of cellulose blown it do not care which direction metal runs. Thanks in advance ROBERT in VIENNA

DEAR ROBERT: Most “barn” trusses are not designed to support a ceiling. You will want to look on your building’s engineered truss drawings for the BCDL (Bottom Chord Dead Load). If it is a value less than five (5) psf, then a ceiling should probably not be installed. If it is five or more, then you should add framing joist hung between bottom chords to properly support a steel ceiling. In all likelihood, 2×6 #2 and better every four feet should prove adequate. Avoid using cellulose insulation, as it is heavy and has chemicals in it that can react negatively with steel.

This entry was posted in Trusses, Ventilation, Rebuilding Structures, Building Interior, Budget, Insulation, Pole Barn Questions, Pole Barn Heating, Pole Barn Design, Barndominium, Pole Barn Planning, Shouse and tagged , , , , , on by .

Built Without Permit, Insulation to Purlins(?), and BIBs Insulation

This week the Pole Barn Guru answers reader questions about potential issues with existing pole barn built without permit, whether or not spray foam directly to OSB is a good idea, and use of moisture barrier with BIBS insulation.

DEAR POLE BARN GURU: We are thinking about putting a purchase offer on this land in Ohio. The manufactured home burned and there is only the 40×60 pole barn left. We’re from central NY with crazy snow loads so I hoped your experience eye could take a quick look and let us know if there are glaring issues. (There was no permit filed for this building) and we’d plan to get a structural engineer if you your initial professional opinion doesn’t just say R-U-N ! LOL I’ve read your blog posts and what others have written. I like your style and knowledge !! I’ve learned more in a week from you than other places by digging a lot. Thank you for sharing your knowledge. Thanks in advance !!Deer in the headlights look, CHARY in FULTON

DEAR CHARY: Thank you for your very kind words, I do try to pass along correct answers and once in a while, be entertaining! You are smart to engage services of a Registered Professional Engineer. Pole buildings erected without permits being pulled tend to have some structural challenges – some of them (such as generally inadequate footings) are ones not visible to a naked eye. Things I would be concerned about: Diameter of footings under columns (this is a frequent builder shortcut). Is there a vapor barrier under slab? (If not, top of slab should be treated with a good sealant) Is slab perimeter insulated? (This can be retro fitted) Are columns adequately pressure preservative treated?

Wall girts may be inadequate to support applied wind loads at site Roof trusses should have bottom chord bracing no less than every 10 feet. Birds are getting into building somewhere. Best of success to you.

 

DEAR POLE BARN GURU: I am building a 24×30 pole building 15 foot wall height. I am l am planning on not putting in a ceiling and insulating directly in the purlins up to the OSB. Soffits are vented but should I put in just some small gable vents for outlet flow? MIKE in SEDRO WOOLLEY

DEAR MIKE: Insulating between purlins directly to OSB is a very bad idea and does not meet Building Code requirements. Here is an article I penned in regards to this very subject: https://www.hansenpolebuildings.com/2023/10/properly-insulating-between-roof-purlins/

 

DEAR POLE BARN GURU: I have a couple of post frame buildings 7 years old with no insulation. If I was going to use BIBs insulation does it need a vapor barrier on the outside wall? TIM in TRAVERSE CITY

DEAR TIM: I have used BIBs in a couple of my own personal buildings (read more here: https://www.hansenpolebuildings.com/2011/11/bibs/). Being fiberglass, it is negatively impacted by moisture. Ideally, you should have a weather resistant barrier (WRB) between your siding and framing/insulation. This will allow moisture to pass out of your wall cavity, but not come in from outside. If you are unable to add a WRB, you might want to consider using Rockwool batts, as they are unaffected by moisture.

This entry was posted in Insulation, Pole Barn Heating, Pole Barn Questions, Barndominium, Constructing a Pole Building, Pole Barn Planning, Ventilation, Building Interior, Professional Engineer and tagged , , , , , on by .

Will I Have Issues With Post Frame Closed Cell Spray Foam Insulation?

Will I Have Issues With Post Frame Closed Cell Spray Foam Insulation?

Reader HEATH in NACOGDOCHES writes:

“I am building a pole barn that I do not plan to heat or cool initially, but would like to insulate due to condensation issues and our hot humid climate. Have there been issues with closed cell spf in post frame buildings. My main concern would be if there ever was a screw to back out and cause a leak. Probably overthinking it, but just trying to make a decision on what makes most sense. I am also open to soffit vents and installing a ceiling and blowing in insulation.”

Screws do not “back out”. Watch a screw being driven in – it pulls the wood fibers up. Wood has an inherent “memory” and as those disturbed fibers return to their natural state, they want to pull screws in (creating even a tighter seal).

Screw leaks are caused by either poor installation, wrong placement (on high ribs rather than flats), or entirely wrong parts. Poor installation will show up right away – either in a good rain storm, or by checking weather tightness by running a water hose on roof. I would recommend second of these prior to any interior finishes.

 

Most of our industry uses #9 or #10 diameter screws and often only an inch long. We found, under even a small load, one inch screws will pull out of lumber – so use 1-1/2″ screws. Next issue is one of time. Eventually slots will form around shanks of #9 or #10 screws, due to cyclic loading from wind. One these slots get long enough, they extend past screw’s washers and you have a leak. We use on larger diameter screw shank diaphragm screws to eliminate this as a challenge. Many are also using screws with neoprene rubber gaskets. These are not UV resistant and will break down due to sunlight. When this occurs, you again have leaks. There is an easy solution – EPDM gaskets. Yes, they cost a bit more, however damage from a single leak outweighs any up-front costs.

If you opt for closed cell spray foam, you want to have it applied directly to inside of steel panels, with no other barrier between insulation and siding or roofing. You will need to mechanically dehumidify, as your building envelope will be air tight. Given your climate, this would be my personal choice.

An alternative would be to blow in insulation over a ceiling. You should then order raised heel trusses to attain full insulation depth from wall-to-wall. Vent eaves and ridge in correct proportions and order roof steel with an Integral Condensation Control factory applied, to avoid having drips in your dead attic space.

This entry was posted in Pole Barn Questions, Constructing a Pole Building, Pole Barn Planning, Ventilation, Powder Coated Screws, Pole Barn Heating, Insulation, Barndominium and tagged , , , , on by .

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.

This entry was posted in Uncategorized, Ventilation, Insulation, Building Interior, Pole Barn Design, Roofing Materials, Constructing a Pole Building, Pole Building How To Guides, Pole Barn Heating, Pole Barn Planning, Barndominium, Pole Barn Structure and tagged , , , , , , on by .

Lots of Bad Advice for Retrofitting Roof Insulation

Lots of Bad Advice for Retrofitting Roof Insulation

Reader DAVE in GALES CREEK writes:

“I’m desperate, or I wouldn’t be bugging you with this. We have a 38×48 pole barn / shop with concrete pad that was on our property when we bought it. There are 4 sections between trusses, and one of those has been walled off as a work area. I really need to insulate the ceiling / roof of this area. For heating purposes and some extra sound absorption. The roof has 2×6 rafters running parallel to the length of the building – no soffits or vents. The existing insulation is vinyl backed fiberglass between the rafters and metal roofing. It does very well for what it is, no problems. I’ve had so many people tell me EVERYTHING I learn is wrong – it’s cost us dearly over the last few years being paralyzed with fear that we might do it wrong and regret it. How would you do this? Most say to tear out the vinyl back fiberglass, fill the rafter cavities with Rock Wool (or fiberglass), an interior vapor barrier and then cover the ceiling with PVC roofing or tin. Others say to leave the fiberglass vinyl backing in place,( Which I prefer) use Rock Wool, but leave an air gap so there will be air flow into the rest of the shop to avoid condensation on the vinyl backing. Like a mini attic space to avoid creating a double vapor barrier? I would use spray foam, but without getting into it, it’s not an option. I’d have to use foam board, rock wool or FB insulation. Could you please help us? Any advice would be so greatly appreciated. We’re losing our shirts on this project taking so long. Anything would be helpful at this point. I’d be glad to send diagrams and photos if need be? Thank you very much for your time either way.”

Mike the Pole Barn Guru answers:

While I am not a fan of vinyl backed fiberglass (aka metal building insulation), provided seams are sealed and facing is not punctured, it does provide a condensation control.

If you were to tear out what you have (would be a painfully tedious project), your only option would be closed cell spray foam directly to roof steel. Why? Because, Building Codes require an inch of clear space between insulation and roof deck from eave-to-ridge. As your building’s roof purlins prevent this from happening, any sort of batt insulation in plane of roof would not be an option.

Provided your trusses are capable of carrying added weight of a ceiling, or you can support a ceiling off of 38 foot walls on each side of this bay, your best option is to blow in insulation directly above said ceiling. First choice would be granulated Rockwool (it is not affected by moisture and does not degrade with time), second would be fiberglass. If using steel panels for a ceiling, do not blow cellulose on top of it, as chemicals in it are likely to react negatively with steel.

Leave attic area above ceiling open to balance of building, so as not to create an unventilated dead air space. Otherwise, you will need to add gable vents (as an air intake) and vent the ridge.

This entry was posted in Insulation, Pole Barn Questions, Building Interior and tagged , , , , on by .

How to Insulate My Pole Barn Roof

How to Insulate My Pole Barn Roof

Reader JEREMY in GREENBRIER writes:

“Looking at building a 50x60x15 pole barn 20 miles north of Nashville, TN. I’m needing recommendations for the best way to insulate. I’m using scissor trusses with no ceiling and I’m planning metal panels on the inside walls. I’m thinking 2×4 girts on the outside of the poles and 2×6 bookshelf girts. Tyvek wrapped and Rockwool between bookshelf girts. I’m not sure how to insulate the ceiling or roof. I will be conditioning the space and keeping it between 78-55 degrees year round. Thanks.”

Mike the Pole Barn Guru says:

Our oldest daughter lives just south of you!

While I realize you have this building pretty well planned out, I will throw out some ideas. Hopefully they will allow you to keep more of your hard earned dollars in your wallet.

With a 50′ span, you might want to consider increasing wall height, rather than using scissor trusses. Chances are good it will be less costly and will provide full height utilization from wall-to-wall.

Rather than using a combination wall girt, if you just do 2×8 bookshelf girts it will take less materials and time to install. 

Robertson County is in Climate Zone 4A, where 2021 International Energy Conservation Code (IECC) requires R60 in roofs and R30 in walls. You can meet wall requirements with 7-1/4″ Rockwool (https://www.hansenpolebuildings.com/2013/03/roxul-insulation/) (batts . If you are trying to insulate the plane of your roof, you will be pretty much limited to spray foam insulation. You could do 2″ of closed cell insulation applied to the underside of roof steel plus 13″ of open cell or 3 & 11, etc. Any of these will become expensive design solutions. You also will end up conditioning a tremendous amount of area above truss bottom chords.

How I would do it….

Order 16″ raised heel trusses. Roof steel with an Integral Condensation Control (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/) factory applied. Vent soffits and ridge in correct ratios (https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/). Install a ceiling, blow in R-60 of granulated Rockwool. This overall combination will be far less expensive than spray foam and certainly far less expensive to climate control.

This entry was posted in Pole Barn Design, Roofing Materials, Pole Building How To Guides, Pole Barn Planning, Trusses, Budget, Insulation, Pole Barn Questions and tagged , , , , , , , on by .

Moisture Control, Insulating Existing Structure, and a Post Rot Fix

Today the Pole Barn Guru answers reader questions about moisture control, insulating a building with a ridge vent, and a solution for replacing posts that have rotted out.

DEAR POLE BARN GURU: Thanks for the abundance of technical information you provide your readers. Like many of them, I inherited a pole barn with the same ceiling sweating, heat, cold issues and need a post construction solution. The slab sweats only in some places. I have a typical wood post with 2×4 horizontal purlins, wood truss and purlin roof, and metal skin walls and roof. My goals are, #1 stop the moisture inside, #2 insulate for moderate comfort (no codes to comply with and I can heat with a wood stove and abundance of wood) , and #3 if I can afford it, skin the walls with T-111 or other wood for an attractive look inside. I did not see any suggestions about double-faced radiant barriers in your other articles. Do you think expanded polystyrene cut to fit in the 1.5 inch cavities to flush with purlins, and then add the radiant barrier (bubble type) stapled over that directly to purlins would be appropriate and not trap moisture? If so, should I allow and air space between the polystyrene and radiant barrier? Many thanks, Mr. Retired…finally! JOHN in CHEROKEE VILLAGE

DEAR JOHN: Thank you for your kind words. If your slab sweats at all, it is likely there is no vapor barrier under it and it would behoove you to apply a sealant. 1.5″ expanded polystyrene (EPS) boards cut to fit tightly and with all seams tightly sealed would give you some degree of insulation (roughly R-7.5 other than at girt and purlin locations). You could add unfaced rock wool batts to increase insulation. Radiant barriers provide next to no insulation value and only function if seams can be perfectly sealed, we’ve actually opted to no longer offer them to our clients.

Unless you want to heat area in triangle of trusses, you may want to consider insulating at ceiling level, then vent dead attic space above.

 

DEAR POLE BARN GURU: Hello Mike. I came across your website while trying to learn more about what to do with the ridge vents in a pole barn when you plan on insulating it with closed cell foam. My wife and I purchased a property that has a 36w x 48L unconditioned pole barn with 8 skylights, a couple of ridge vents and (2) sets of huge doors on each end. While we know this will never be a tight building, we need to insulate it for our pets (10) dogs and (11) cats, and for a hangout area for us to spend time with them rather than inside our home.

We have a high-end American Standard heat pump split system that will condition the entire space.

Would you be able to give me any advice on what you recommend I do regarding the existing ridge vents? I’m not sure if I should insulate around them and leave them as they are…open. Or, should I temporarily trim out around them and seal them for the time being?

Any information you could provide me on this topic would be greatly appreciated. ROGER in HOUSTON

DEAR ROGER: With those large sliding doors, your investing in closed cell spray foam may be for naught. If your expectation is to be able to control any sort of heat loss/gain you should consider replacing them with insulated steel sectional overhead doors.

On to your question – seal off ridge vents and spray foam across skylights (or, even better) replace them with steel roofing before insulating.

 

DEAR POLE BARN GURU: What are my options on repairing 32×40 all 6×6 posts are rotted off ground level. Floating slab, perma colum, helical peir, or strongway sleeve. CHAD in GREAT BEND

DEAR CHAD: I would repair one column at a time. Temporarily support roof system being supported by a column. Cut column off above point of decay. Excavate embedded portion of column and remove – hole being dug to be at least below frost line. Insure bottom of hole is firmly compacted. Place a sonotube in hole, attach an ICC approved wet set bracket to bottom of column and backfill with premix concrete. Compact granulated fill around sonotube in six inch lifts. Repeat at each column.

 

 

This entry was posted in Concrete, Building Interior, Columns, Pole Barn Heating, Pole Barn Questions, Ventilation and tagged , , , , , on by .

Help! My Barndominium Roof is Dripping!

Help! My Barndominium Roof Is Dripping!

Reader TIMM in WHITEFISH writes:

“Thanks for taking my question. I recently built a barndominium in NW Montana. I tried to find someone to build it for me, but the demand and cost in the area had gone up so much that I had to do almost all the work on my own. I was not completely unfamiliar with building but not an expert by any means but I was able to get it built with helpful videos found online. I finished the home in late October and have moved in. The home is 28’x36′ with 10′ walls and is all living space, no garage. I had planned on doing spray foam insulation around the entire shell of the barn and had hired a company in August to come out and spray the barn but they were not going to be able to get to the building until December at the earliest but we were willing to do it and fight through the winter in our camper. Our plumber mentioned a product to us that he had seen some other clients use called Prodex that had similar characteristics of spray foam with a reflective surface on both sides and it was something I could do myself and much sooner. I did some research and the product looked good and the reviews looked good so I bought some and installed it. The steel was already on when I installed it so the Prodex was installed by stapling or screwing to the Purlins/Girts around the whole building which was an install method on their website. While we were mudding/painting/texturing I noticed some condensation in the attic in between the steel and the Prodex insulation (I could see where it was coming through a seam in the Prodex). I asked some people and they thought it was just because I was putting a lot of moisture in the air that was causing the condensation and it would dry out when we were done. On a recent trip up to the attic I noticed that the steel is still condensating when it is cold outside and the Prodex itself seems to be condensating as well. I emailed Prodex and they told me that it is caused by cold air moving across the inside surface of the steel and I should put foam around the ridge cap, eave edge of roof and tops of wall. I have foam around the ridge cap, but nothing on the ridge cap ends, I have foam on the eave edge of the roof, but only in the high ridge parts, and I have nothing on the walls. I am also concerned that this is happening inside of the walls which may lead to a bad mold problem next summer. My question is, how do I get it to stop condensating? I am ready to do whatever I need to do. I just don’t want to throw ideas at the house until something works. As far as ventilation goes, I am sure I do not have enough but was hoping to address that in the summer months. I do not have eaves on the building which I regret so my only real ventilation is the ridge cap and the little bit that may be coming through the ridges on the eave edge of the roof. I thought about gable vents, but I felt like that would let too much cold air in and would make the issue worse, but maybe that is what I need? If I put in gable vents, do I pull out the Prodex insulation and leave bare metal on the inside of the attic? I am trying to figure out a way to reduce the moisture right away (dehumidifier?) while I work on a long term solution but I don’t know which direction to go to solve this issue. I thought about pulling off the steel and putting in plywood sheeting, but we are in the middle of winter and that would have to wait until Spring at least and I am afraid I will end up with too much water damage by then. I have even considered putting sheeting under the roof and replacing the outside walls with wood siding but the cost would be high and I feel like there should be a solution to this issue. For heat we electric wall heaters (Cadet in-set wall units) occasionally and a pellet stove most of the time. We put the Prodex insulation as well as blown insulation in the attic to about 12 inches deep and we put Prodex as well as rolled insulation in the walls for a total of about an R30 value. Dryer and bathroom vents both go outside and nothing is venting into the attic. Any help would be appreciated! Thanks.”

Mike the Pole Barn Guru says:

Kudos to you for doing a D-I-Y. Sadly you were lead to a product (Prodex) claiming to be insulation, however in reality it is a condensation control, and only if totally sealed.

All of these issues could have been easily addressed at time of construction had your building kit provider given you proper advice.

First thing to do is to get your attic properly ventilated – you need to add at least 121 square inches of NFVA (Net Free Ventilating Area) to each gable end. This will give you an air intake and your vented ridge will then function as a proper exhaust. By itself, this should greatly minimize, if not totally cure your problems.

Pole Barn Guru BlogAs time allows, remove roof Prodex, have two inches of closed cell spray foam applied to roof steel underside, and increase thickness of blown in attic insulation to R-60.

If you do not have a well-sealed vapor barrier under your concrete floor, if possible, seal top side of it (this is where moisture is coming from).

Heating as much as possible with your pellet stove will also help to dry your interior air out and provided your slab is sealed, should help greatly.

I do have some concerns about your walls, if you have faced insulation batts with Prodex on outside of batts, you are potentially trapping moisture between two vapor barriers. If this is indeed your case, come Spring, remove siding (one wall at a time) , remove Prodex (as much as possible) and add a Weather Resistant Barrier (Tyvek or similar) to the exterior of framing, properly seal all wall openings and reinstall wall steel.

This entry was posted in Insulation, Pole Barn Heating, Pole Barn Questions, Roofing Materials, Barndominium, Ventilation and tagged , , , , , , , , , , , on by .

Screw Penetration, Truss Carrier Requirements, and Roof Insulation

Today’s Pole Barn Guru answers reader questions about screw penetration into decking/substrate, header aka truss carrier requirements, and a proper roof insulation solution.

DEAR POLE BARN GURU: Should the screws for exposed fastener metal panel roofing COMPLETELY penetrate the 1/2″ plywood decking/substrate? STEVE in WARREN

DEAR STEVE: For through screws, they should not only completely penetrate any substrate, but also at least an inch into underlying purlins. Relying upon screws into decking only could prove to be a failure looking for a place to happen in a severe wind situation.

 

DEAR POLE BARN GURU: On a 14’ x20’ building with 4×6 post 8’ tall what are the requirements for the header beam or beams? Can I use two 2x10s one out and one inside? TIM in STATE ROAD

Ask The Pole Barn GuruDEAR TIM: Header beam (aka truss carrier) requirements can be determined by a Registered Professional Engineer and are based upon this formula:

(Roof live and dead loads) x (1/2 span of truss + any eave overhang in feet) x (column spacing in feet squared)

Divided by

8 x Sm (Section modulus of proposed beam) x Fb (Fiberstress in bending of proposed beam) x Cd (Duration of Load)

If resultant is less than 1, then beam is okay.

Here is an example, based upon assumption your building is in a minimal snow area, steel roofing over purlins, no or light weight ceiling) columns are every 10 feet, one foot overhangs and available lumber is 2×10 SYP #2

(20 psf + 10 psf) x (14’/2 + 1’) x 10’^2 / 8 x 21.3906 (Sm of a 2×10) x 800 x 1.15 = 0.15 <= 1

For sake of this example, a single 2×10 #2 SYP would be adequate in bending. It may not be adequate for meeting required bearing area (can be confirmed with truss manufacturer).

Beams and connections should also be verified for adequacy against uplift forces, as well as deflection.

 

DEAR POLE BARN GURU: I’m about to build my ‘Miracle Truss’ building which uses steel trusses with lumber purlins/girts. I have a concrete slab with 2″ Styrofoam and radiant heat to provide some warmth in the winter. I’m thinking of using foil/single bubble vapor barrier in between the roof sheeting and wood purlins. In the future I’d like to add bat insulation to the inside of the roof. For the walls I’m not sure if I should use a foil radiant film – non-permeable…or if I should instead use house wrap like ‘Tyvek’. Again, as time and $$ allows I’d like to add bat insulation and maybe OSB half way up the walls. I’d appreciate your professional opinion on how best to ‘wrap’ my building and also ‘future proof’ it in case I happen to win the lottery and can afford to fully insulate it someday. Thank you. RICK in HILLSBORO

DEAR RICK: Code will not allow you to place batt insulation between your purlins unless you have at least an inch of continuous airflow above from eave to ridge. Impossible to do given orientation of roof purlins.

I would use two inches of closed cell spray foam directly to underside of your roof steel. Later, you could fill balance of cavity between purlins with unfaced rock wool, or open cell spray foam. For your walls, use a Weather Resistant Barrier (aka house wrap) and you can add either Kraft faced batts or unfaced batts with a 6mil vapor barrier on the interior at a later date.

 

This entry was posted in Trusses, Ventilation, Professional Engineer, Insulation, Pole Barn Questions, Pole Barn Design, Roofing Materials, Pole Barn Heating, Constructing a Pole Building, Pole Building How To Guides and tagged , , , , , , on by .

Pole Barn Homes, Pole Barn Home Financing, and Insulation Assistance

This Monday the Pole Barn Guru answers reader questions about pole barn homes, help with finding a lender for a post frame home, and an insulation solution for a gambrel style building.

DEAR POLE BARN GURU: Hello, do you have any information on your pole barn homes? Looking to build in lower Michigan. HOLLY in WHITMORE LAKE

DEAR HOLLY: Thank you for your interest in a new Hansen Pole Buildings’ fully engineered custom designed pole barn (post frame) home. A great source of information to get you started is to visit www.HansenPoleBuildings.com, navigate to upper right corner and type BARNDOMINIUM into SEARCH box, then ENTER. Up will come a plethora of articles relating to pole barn homes. One of our Building Designers will be reaching out to you to assist, as well.

 

DEAR POLE BARN GURU: Hi, We are in the planning stages for our pole barn house we want to build. My question is about Lenders/financing for a Pole barn home- are there certain lenders that specialize in financing for Pole Barns? We were just going to apply for an FHA construction loan thru Rocket mortgage to cover the Lot purchase and the construction. Does Hansen offer a financing solution? Is there a better choice of lender that we should consider?

Thanks! MICHAEL in SHERMAN

DEAR MICHAEL: While there are lenders who specialize in pole barn home financing, you can use virtually any lender provided you follow the suggestions in this article: https://www.hansenpolebuildings.com/2020/06/things-to-complete-before-going-to-a-barndominium-lender/

 

DEAR POLE BARN GURU: I have an 80X40 Gambrel roof barn. It has metal on roof. I want to take off the metal and insulate the outside of the roof, to a commercial approved R 30. Should I leave the 2×4 strips going across the roof, insulate in between the 2×4 with closed cell foam and then use sips to make up the rest of the R Value? Or should I just continue with spray foam. Top ridge of roof is close to 40′, will spray foam to get to R30 be too heavy for the roof? I need to insulate the walls on the outside as well, but I can do some insulation on inner building as well. I would like to turn this barn into a commercial gathering space, so codes would need to be enforced. GORDON in GENESEO

DEAR GORDON: Unless there is some issue with your current steel roofing not performing (leaks or rust) I see no reason to remove it. SIPs, while a relatively ‘trick’ design solution, are also very expensive https://www.hansenpolebuildings.com/2020/02/sips-for-barndominiums/. An R-30 SIPs panel will cost roughly $4.66 per square foot and weighs in at a hefty four psf (pounds per square foot). To get to R-30, you could do two inches of closed cell spray foam directly applied to inside of your roof steel, then just over four inches of open cell to it, with a weight of under a pound per square foot – it will be less of an investment and you do not have to remove your existing roof steel.

Regardless of how you insulate, you should have a Registered Professional Engineer evaluate your structure for adequacy as a commercial venue.

 

This entry was posted in Insulation, Gambrel, Pole Barn Questions, Barndominium, Pole Barn Design, Roofing Materials, Pole Barn Homes, Pole Barn Heating and tagged , , , , , , on by .

Steel Roofing and Siding Over Purlins

There is just plain a lot of bad (and scary) information floating around out there on the internet. For whatever reason, people will believe a random unqualified answer from a stranger, rather than going to a highly educated expert (e.g. Registered Professional Engineer).

Reader DYLAN in BEDFORD writes:

“I am building a 50×60 using 2×6 stud frame walls. Trusses 4’OC. The garage area (30×60) will have around 12’ceiling. The living area (20×60) will go back and stick build ceiling rafters 2’OC to make 8’ceilings. 12’ ceiling on the living area is just more to heat and cool – not necessary. My builder right now plans on putting 2×4 purlins and 2×4 girts on roof and side walls. Then wrap the whole thing with tyvek and out metal on. 

My question starts with is this ok? 

Should I consider plywood/osb on the roof or walls in lieu of 2×4 purlins/girts?

Are 4’oc trusses ok if I am going back to the living area and building ceilings 2’oc?

Are 2’oc rafters ok assuming I finish the ceiling with 5/8” drywall or wood tongue groove or similar?

I will probably spray foam insulation in the living area. This should help with noise during rain on the metal roof.”

Mike the Pole Barn Guru responds:

My recommendation would have been for you to erect a fully engineered post frame building, rather than spending tens of thousands of extra dollars in an attempt to make a stick framed house look like a pole building.

Ultimately how your building is assembled structurally should be up to whatever engineer you (or your builder) hire to provide your home’s engineered plans. Building Codes do not allow for stick framed walls taller than 11’7″ without engineering, so you should be there already.

Steel panels should not ever be screwed into OSB only and even plywood only would only be on roofs if you are using a standing seam (concealed fastener) steel. I (and most likely your engineer) will specify 2×4 or even 2×6 girts and/or purlins in order to provide a proper surface to screw steel panels to. Your trusses every four feet may be adequate in your living area, it will depend upon how your engineer designs structural attachment of your furred down ceiling, as well as weight supported by it. Rafters 24 inches on center will provide sufficient support for 5/8″ drywall.

You should not place Tyvek between roof framing and roof steel – as Weather Resistant Barriers (WRB) allow moisture to pass through. This could allow condensation to be trapped between your home’s WRB and roof steel, causing premature deterioration.

This entry was posted in Professional Engineer, Pole Barn Questions, Pole Barn Design, Pole Barn Homes, Building Department, Constructing a Pole Building, Pole Barn Planning and tagged , , , , , , , , , , on by .

Fishing Cabin Insulation

Fishing Cabin Insulation Blog-Compliments to Rick Carr in sharing this post on how he insulated his fishing cabin. 

My insulation challenges are a little unique due to having an above ground crawl space, radiant floor heating above the sub floor, 2×8 and 2×10 walls and having a partial attic area (over the bedrooms) with the remainder a vaulted ceiling.  My insulation is done and the drywall is going up.  The test for the plan will wait until next winter.

Here is what I did.

First I had closed cell foam sprayed.  In the crawl space, walls 3 inches closed cell spray foam, completely sealed and R 21.  Also we sprayed the underside of the subfloor to 1 ½ to 1 ¾ inches.  The goal was to get R 1- to 12 on the underside of the floor.  The radiant floor people tell me that heat moves to cold, so R 12 under the floor will have heat going up into the living space rather than down into the crawl space.  There is also R 10 foam board and poly under the concrete.

I also had 3 inches of spray foam, R 21, on the underside of the roof steel.  The drywall will go on the underside of the roof purlins.  We used 2 x 10 roof purlins to get a 9.5 inch cavity for insulation.  I put Tyvek under the roof steel, so the spray foam actually adheres to the Tyvek, this will allow replacement of roof sheets, if ever needed.  This still leaves a 6 inch space for R 21 unfaced batt insulation.  Spray foam people will tell you that because the spray foam completely seals the effect is greater than the R value.

The Attic side of the divider wall was also prayed with 3 inches of closed cell foam.  There wasn’t a normal 6 inch cavity to fill with batt insulation which made the spray foam a good choice for this.  We also blew in 16.5 inches of fiberglass insulation into the attic above the bedrooms for R 49 in that area.

 The walls are another matter.  The 42 foot walls on the north and south sides of the building are 2 x 10 walls with 9.5 inch cavity.  The 30 foot east and west walls are 2×8 walls with 7.5 inch cavity.  I chose blown in wall insulation for the walls.  It is commonly thought that you can only have a pro blow insulation into your walls, not so, I did it myself, with some help.

I chose Owen Corning’s Procat product and system, which can be purchased from contractor supply houses. https://www.owenscorning.com/insulation/products/procat  This is the same product as used in the ceiling.  The supply house will loan you the blower, which has a control at the end of the hose.  You staple Insulweb netting to the framing, cut a small slit in the netting, insert the hose and blow it in.  This might be a little more costly than batt insulation, but where do you find batts for 2 x 10 walls?  Also the electric all over the place gets in the way of batts, no problem, filled in and around.  The blown in insulation fills into all cracks and spaces.  What you spend in the product is also made up in time/labor savings; it goes very quickly once you get the hang of it and the netting up.

The puffing or pillowing is not a factor because the product is light enough that the drywall will straighten it.  Also you can use your free hand to minimize the pillowing if you have a large cavity.  The product R value for 5.5 inch cavity walls (2×6) is between R 22 and R 24 depending on how full you pack it in.  With my 2×8 and 2×10 walls, the R value is literally off the chart, well over R 30.

 

I think I’ll be snug this winter.

This entry was posted in Insulation, Barndominium, Pole Building How To Guides, Building Interior and tagged , , , , , , , , on by .

Plans Only? Moisture Barriers? and Two Story Houses?

This week the Pole Barn Guru answers questions about “plans only” purchases, proper use of moisture barriers when adding insulation to an existing building, as well as the possibility or building a two story post frame house.

DEAR POLE BARN GURU: Do you offer just the plans? I own a sawmill and would like to mill my own lumber for my project. With the exception of the trusses. I can also source the metal roofing locally. THERON in WALDEN

DEAR THERON: Thank you for your inquiry.

We are unable to provide just plans as it becomes a liability issue for our engineers – it takes away insuring materials specified actually end up being delivered to your building site.

 

There are also issues with attempting to use home milled lumber: https://www.hansenpolebuildings.com/2020/01/free-home-milled-lumber/

As an example, in sourcing your own metal roofing locally, even if steel quality was equivalent, they will not be able to provide powder coated diaphragm screws to attach it.

DEAR POLE BARN GURU: Purchased property with existing fairly new pole barn. Question is regarding wall insulation. Some installers say use double backed 6 inch glass rolls insulation under my drywall. Then I spoke with another & he says mandatory to spray closed cell foam or condition will ruin insulation…..there is no vapor barrier wrap on outside. Any help would be appreciated. Thanks, DAN in GRANBURY

DEAR DAN: You should have some sort of barrier between wall framing and wall steel to prevent condensation within the wall cavity. Wall cavity moisture can lead to a plethora of challenges – premature rusting of steel siding, rot, mold and mildew on wood framing and lack of performance of fiberglass insulation.

 

You could remove wall steel and add a Weather Resistant Barrier (highly labor intensive and things never go back together as well as they were originally assembled), or do a two inch coating of closed cell spray foam, then use fiberglass inside of it.

Here is my Ultimate Guide to Post Frame Building Insulation: https://www.hansenpolebuildings.com/2019/11/post-frame-building-insulation/

DEAR POLE BARN GURU: Hi there! I was wondering if y’all do two story residential pole houses? Second question, if I sent you guys a rough sketch of a blue print would you guys be able to give me an estimate off of that? (with included trim choices and such)

Thank you! MAX

Gambrel roof pole barnDEAR MAX: I happen to live in a two story post frame shouse (shop/house) with a partial third story. Back in the great state of Washington, I also have a three story post frame building with roof top deck! We can provide any low rise building with up to 40 foot tall walls and three floors (or 50 feet and four floors with sprinklers).

 

Send us what you have and chances are very good we can get you an estimate from it (we might want to ask you a few questions about what you intend to build).

 

This entry was posted in Ventilation, Building Interior, Pole Barn Homes, Post Frame Home, Insulation, Barndominium, Pole Barn Questions, Pole Barn Design and tagged , , , , , , on by .

What Home Builders Use for Insulation

With barndominiums, shouses (shop/houses) and post frame home building on a brisk upswing, a considering factor is how to insulate new homes. Becoming as close to (or reaching) net zero (https://www.hansenpolebuildings.com/2019/01/net-zero-post-frame-homes/) as possible should be a goal of any efficient post frame home design.

Rather than me just blathering about what my opinions are, I felt of interest to share what American home builders are actually using for insulation. Keep in mind these results are from traditional stick frame construction – where a plethora of redundant wall framing members often make insulating and avoiding thermal bridges much more of a challenge than with post frame construction.

For your reading pleasure:

Originally published by the following source: ABTG Staff — August 7, 2019 

The 2019 Annual Builder Practices Survey, which had more than 1,600 homebuilder participants this year, provides some powerful insight into the thermal products market in the U.S.

According to the survey, adoption of more stringent energy codes, homebuyer demographics driving the demand for lower energy bills, labor, and building material costs are prompting homebuilders to seek higher performing insulation that is also budget-friendly. Not surprisingly, these two factors seem to be tugging the market in different directions.

The performance vs. value tradeoff in the decision to specify insulation materials continued to be a key question for most homebuilders. According to the survey, some builders would use full-cavity foam insulation, if the cost was lower. The real challenge is that some homebuilders still believe fiberglass is the best bang-for-the-buck, and if they’re looking for higher energy performance they will actually invest in things like energy efficient windows and HVAC systems over upgrading the insulation.

A builder’s insulation preference is also heavily influenced by geographic area, price-point of their homes, and how many units they build annually. For example, fiberglass batt has its deepest market penetration in Pacific states and lowest in West South Central states. Smaller builders (10 or fewer starts-per-year) are three times as likely to use spray foam than larger builders (more than 50 starts-per-year).

Source: 2019 Annual Builder Practices Survey, Home Innovation Research Labs

Difference in insulation usage was less variable when it came to home size as per building size. Yet, spray foam was about twice as likely to be used in luxury homes than starter homes, as an example. Conversely, fiberglass batts was more likely to be put in starter homes than luxury homes.

This entry was posted in Building Contractor, Post Frame Home, Barndominium, Uncategorized, Insulation, Pole Building Comparisons, Pole Barn Planning and tagged , , , , on by .

Fire Rated Spray Foam Insulation

Spray foam insulation has become increasing popular for achieving high R value building shells. One downside of spray foams has been they are not being fire resistant.

I was pretty excited to read this on a post frame building contractor’s website:

“Installing foam insulation can either be sprayed or foamed-in-place. Foam has the ability to create an air barrier for the smallest of air leakages. Spray foam doesn’t retain water, providing excellent protection from the growth of mold and mildew. While foam insulation is generally more costly than other insulation options, it does have higher R-values and is fire rated.” 

As this particular contractor is a friend of mine, I dropped him back this question, “Spray foam insulation is fire rated?”

To this he replied, “Yes, some are, Tiger makes one.”

News to me, so I fired up my laptop and headed to Google, looking for more information.

Tiger Foam™ insulation (https://tigerfoam.com/sprayfoaminsulation/), according to their website, “is a proven leader in providing spray foam kits, supplies and accessories to homeowners and contractors alike.”

Again, according to their website, “We offer retails sales for small projects and wholesale, bulk pricing for bigger jobs. Our expert customer service team is always available to answer questions and help plan projects. Whether you’re trying to save money on your monthly energy bills or working to satisfy your customers. Tiger Foam can help. Most of all, our products provide high performance and great value. Become a customer today and get you the tools you need to start saving energy dollars!”

Well, sure enough, Tiger Foam™ offers a ‘Fast Rise’ kit providing a Class 1 Fire Rating. This fire rating means this building material is highly resistant to fire and does not spread flames quickly. Building materials with a Class 1 fire rating are often man-made or nonorganic substances. Other Class 1 building materials include brick, tile and cement.

I have never personally installed Tiger Foam™, however I have paid to have closed cell spray foam insulation installed by a professional installer. If you are considering using a closed cell spray foam for your new project, discuss fire rating with your installer of choice.

This entry was posted in Barndominium, Insulation, Pole Barn Design, Pole Barn Planning, Pole Barn Structure, Building Interior, Post Frame Home and tagged , , , , , , on by .

Pole Barn Cabin Part II

Today’s blog is a continuation from yesterday….Rick Carr, Senior Building Designer for Hansen Buildings shares his thoughts on planning his new pole barn cabin.

From JA Hansen, co-owner of Hansen Buildings….Thanks Rick!

Next I dealt with the crawl space:

After deciding that I want to do a crawl space, several design issues arise and decisions on how you will deal with those issues can affect how the building is designed and ordered.  All reading on crawl spaces emphasize making sure that you avoid moisture issues in the crawl space.  Next you need to do something to avoid losing heat to the ground and out the sides of the crawl space, this crawl space being above grade.   How tall do you make the crawl space?  Do you “condition” the crawl space?  How do you insulate it if you do “condition” the space?  Most crawl spaces are underground with a foundation wall, but that is not the case with post frame buildings so there is very little information out there on how to plan the post frame crawl space  and to “do it right”.  I have read the five blogs articles on crawl spaces, but there are still unanswered issues.

https://www.hansenpolebuildings.com/2013/03/crawl-space/

https://www.hansenpolebuildings.com/2016/04/foundation-and-crawl-spaces/

https://www.hansenpolebuildings.com/2018/06/conditioned-post-frame-crawl-space/

https://www.hansenpolebuildings.com/2018/02/insulating-post-frame-home-crawl-space/

https://www.hansenpolebuildings.com/2016/12/cost-savings-crawlspace-vs-slab/

I will present what I think that I want to do and I’d like to get Mike the Pole Barn Guru’s ideas on it with a question or two.

I plan to condition the space, so I would put down between 6 and 10 mil plastic, then 2 inches of foam board insulation followed by pouring a concrete floor, just enough to keep critters out.  I plan to use BIBS insulation in the walls, so I would extend that down the exterior crawlspace walls to the concrete.

 

The radiant floor heating people that I am talking to have recommended that I put between R-13 and R-15 insulation on the underside of the sub-floor.  The reasoning is that heat wants to move to cold and that you don’t need the crawl space heated to the same temperature as the living space; so insulating the underside of the floor keeps most of the heat up in the living space.  I need to talk to the insulation contractor about what type of insulation to use here.  Spray foam might be good, but the spray foam would make working on any plumbing or electric that is run below the floor very difficult, partially defeating one of the purposes of having the crawl space.

The plastic with the concrete over the top should control the moisture issues coming up from the ground.  The 2 inches of foam insulation under the concrete should help to prevent losing heat to the ground. The concrete should keep critters out and allow using a “creeper” to move around down there.  I haven’t decided on the height, but I’m thinking that it should be three feet.  When on all fours, I am almost three feet tall.  I am 6’3” and it has to be functional.  I would need assistance to figure out how high to make the top of the floor to yield the three feet considering the concrete and foam.

I have not yet discussed this plan with the building inspector.

So Mike, the questions; do you think that this is a good plan?   Would I be able to put in the 2 inches of foam board and the 2- 2 ½ inches of concrete (normal concrete floor being 3 ½ inches) without doing anything different to the splash boards considering that the splashboards are 2×8’s and that there will not be any door thresholds to be worried about?

Stay tuned for Mike the Pole Barn Guru’s answers in an upcoming blog.

This entry was posted in Insulation, Pole Barn Design, Pole Barn Planning, Concrete, Footings and tagged , , , , , on by .

Insulation Values Reflect Real-World Energy Performance?

Insulation R Values Reflect Real-World Energy Performance?

Energy efficiency has become huge for post frame building construction. More and more people are discovering post frame buildings as being a cost effective design solution for residential and commercial construction.

Long time readers of this column have seen article after article in this vein, increasing with time. You have also had an opportunity to witness questions from many current post frame building owners who wished they would have designed appropriately to begin with. Proper advance planning can certainly help to achieve desired results.

Let us assume, for a moment, you have created a post frame building with commercial 2×8 bookshelf wall girts and 22 inch high raised heel trusses. In your walls, BIBs https://www.hansenpolebuildings.com/2011/11/bibs/) fiberglass insulation 7-1/4” deep has been used. This will give a laboratory R value somewhere in excess of 30. In attic space, 20 inches of blown in fiberglass will provide a R value of over 60. You have done your work and are happy your decision will give a more than satisfactory end resultant.

Then along I come and poke holes in your investment.

Keep in mind, my very own post frame home has fiberglass insulation very much like our imaginary scenario above.

The most common yardstick for measuring insulation performance will be R value, but there’s a problem. Insulation packaging shows lab analysis of R values, but it’s based upon used testing completely eliminating air movement from results. This matters a lot with fluffy insulation materials because air movement greatly lowers real-world insulation performance. Drafts and air currents often happen within wall cavities and attics and this will be why real-world insulation performance can be significantly lower than advertised values.

Alternatively, insulation products not allowing air movement through them (spray foams and rigid foams, for instance) have real-world insulation values almost identical to what you see printed upon packaging and used in advertising. Their performance doesn’t decline. Air-impervious insulations can be more than twice as effective as air-porous insulations of identical R value under real-world conditions.

Where does all of this leave us as post frame insulation specifiers and building owners?

When I added an exterior elevator shaft to our post frame home two years ago, my insulation choice was closed cell spray foam. I did make an error in that I did not listen to my own inner voice. Our local installer made recommendations for thickness I felt were insufficient, so I had roof and wall sprayed one inch thicker. I should have gone thicker yet as there was plenty of space available to fill. As a result the elevator shaft is cold and drafty into our living space.

Considering closed cell spray foam? Think it may be expensive? Consider its performance will probably be twice as effective as fiberglass and closed cell spray foam suddenly doesn’t seem so costly.

 

This entry was posted in Insulation, Pole Barn Design, Pole Barn Planning and tagged , , , , on by .

Examining a Light Steel Truss Frame Building

Examining a Light Steel Truss Frame Building

I have never owned or assembled a light steel truss frame building. A gentleman named Stan Floyd worked for me as a salesman when I owned M & W Building Supply. Stan’s dad had fabricated light steel truss frame buildings in Arkansas and Stan was interested in developing this concept in Oregon and Washington. With my blessing Stan founded Web Steel Structures in Sandy, Oregon and found out things weren’t quite like they had been in Arkansas – where building permits, if even required, were issued far more liberally. Northwest jurisdictions required engineering for both frames and buildings, as well as a need for a higher degree of control over welder competency.

Reader DEBORAH in OMAHA writes:

“Did pic come through?

Does this look viable at 30+ years old?

Tear down? I’m looking at buying this property and I’m wondering if I’m going to be the one tearing this 180’ x 85’ building down…

There are only 4 bolts holding the truss frame together at center. Bays are 18’ on center. Every other bay has a criss cross bracing with wire (X) that is of steel cable – somewhat loose. I think there is another cross at the ceiling in kind of a strange place.

I believe the purlins are 2 x 8 as opposed to 2 x 10 which might be better. Building is in Southern IL near KY border.

I think this may have been a Cuckler kit. But I’m not sure. I’ve contacted Star Buildings to see if they know.

Thoughts?

I called an SE for a site visit and load calc and I know that will be about $12,000. It would be estimated as steel quality is unknown. Site visits for just a nod are about $900.”

Dear Deborah ~

Thank you very much for sending photos.

You are looking over a light steel truss frame building – not a post frame building. I am not a gambling man, however I would wager there was no actual engineering done for this structure to start with. Light steel truss frames, such as this, are also rarely engineered. More often than not, frame designs are just like daddy used to do them, so they must be good. Well, engineering does not quite work like this.

Some observations from your photos – minor discolorations appearing as “runs” down sides of roof purlins are due to condensation. No steel roofed building should be constructed without some sort of mechanism to minimize condensation. Only realistic fix for future condensation control would be to have closed cell spray foam insulation placed below roof surface. This insulation should be a minimum thickness of two inches and in most areas a going rate of about a dollar per square foot, per inch of thickness. You could be seeing a $30,000 bill.

Purlins with major blackness have mold due to roof leaks. This mold can be removed, but will prove to be labor intensive. I’d replace any roof ‘skylights’ with steel panels. If they have not yet begun to leak, they will in time.

Unless roof purlins are some grade higher than #2 & btr, they are over stressed in bending and likely have deflection issues. Chances are good wall girts have similar challenges.

In summary, if you decide to invest in this property I would recommend you not go inside this building when snow sticks to roof or winds are over 50 miles per hour. Insure it heavily (for non-depreciated replacement cost) and don’t keep expensive horses inside it.

For history buffs – Cuckler Building Systems division of Lear Siegler Inc. (LSI), was purchased by Star Manufacturing Company in 1986. With manufacturing locations in Monticello, IA and Turlock, CA, Cuckler had annual sales of approximately $20 million. Cuckler Steel Span Company had previously been acquired by LSI in 1970. I’d be interested in any stories about Cuckler Steel Span’s earlier years.

 

This entry was posted in Trusses, Pole Barn Questions, Pole Barn Design, Pole Buildings History, Pole Barn Structure and tagged , , , , on by .

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.

 

 

 

 

This entry was posted in Ventilation, Footings, Insulation, Pole Barn Structure and tagged , , , , , on by .

Attic Insulation Types

Attic insulation has been a recent popular topic of discussion – so rather than reinventing the wheel, I’m sharing a relevant article written by Structure Tech Home Inspector Reuben Saltzman.
Originally published by the following source: Minneapolis Star Tribune — February 6, 2018
The following article by Reuben Saltzman was produced and published by the source above, who is solely responsible for its content. Hansen Pole Buildings is publishing this story to raise awareness of information publicly available online and does not verify the accuracy of the author’s claims. As a consequence, Hansen Pole Buildings cannot vouch for the validity of any facts, claims or opinions made in the article.

What’s the best attic insulation? That depends on your definition of “best”. What’s going to perform the best is definitely not the most cost-effective way to insulate an attic. But surely, you already knew that.
And I didn’t call you Shirley.
First, let’s discuss the most common types of insulation available for attics; spray foam, loose-fill fiberglass, cellulose, and fiberglass batts. Those aren’t the only types available, but they make up the vast majority of what’s used in Minnesota attics. For the listed R-values below, this refers to the material’s ability to resist the transfer of heat and is all per-inch. The higher the number, the better. The minimum R-value for a new Minnesota attic is R-49.

Fiberglass batts
Unfortunately, the easiest way to add insulation to just about any place in your home is to install fiberglass batts.  Fiberglass batts are typically the worst insulation for any job, but they’re easy to pick up in the store and easy to roll out, so people use them. The image below shows an atrocious installation at a two-year-old home in an upscale neighborhood of an inner-ring suburb of the Twin Cities. Yep, this passed the city inspection.

I won’t even discuss R-value because fiberglass batts have no place in an attic. Just don’t go there.

Cellulose
Cellulose is made from recycled, ground-up paper with boric acid added for insect control and fire resistance.  If you choose to install cellulose yourself, you can buy the insulation in bags from your local home improvement store. If you buy enough, they’ll probably let you use an insulation blower for free. Don’t try to buy a single bag and spread it out by hand for spot-insulation; it’s way too densely packed (ask me how I know). The DIY cellulose insulation method is very dusty, but it’ll get the job done.  If you hire a pro, they’ll use wet-spray cellulose, which adds a small amount of water to the cellulose to help control the dust and to slightly increase the insulation value per inch.

Cellulose has an R-value of approximately 3.5 per inch. The part that I love about cellulose is its ability to control air movement. While it doesn’t actually create an air barrier, it’s dense enough to stop most air movement to help control frost in attics. Not completely, of course, but it does a pretty good job. The same cannot be said for fiberglass.
If you check with the Cellulose Insulation Manufacturers Association, they’ll assure you that cellulose is definitely your best choice for insulation.

Loose-fill fiberglass

This seems to be all that’s ever used in new-construction homes and has an R-value of approximately 2.5 per inch. Like cellulose, you need a big machine to blow it in. You can’t simply buy it in bags and spread it around yourself. My biggest complaint with fiberglass is that it’s itchy and it’s a lung irritant. I’ve found that older fiberglass is way worse on your skin and lungs than the newer stuff, however. I have no scientific evidence to back this up, but I don’t need any. I’m completely sure of this based on personal experience.

Side note: I wouldn’t dream of doing any type of insulation work without wearing a respirator. Heck, I won’t even enter an attic without one.

There was a widely publicized study conducted by Oak Ridge Laboratories in 1991 that said that loose fill fiberglass insulation lost a lot of its insulation value once temperatures dropped below 20 degrees, making loose fill fiberglass an inferior product when compared to cellulose.  I contacted Andre Omer Desjarlais at Oak Ridge Laboratories about this issue, and he said: “This was true 20 years ago but all fiberglass manufacturers have changed their products appreciably since then and this is simply no longer an issue.”  I also contacted several insulation manufacturers about this, and they said the same thing and sent me some great information, which I posted on my website many years ago; click any of these links to read the documents from Certainteed, Johns Manville, or Owens Corning.  Loose fill fiberglass insulation will still experience convection, but not nearly as much as old fiberglass used to.
If you check with the North American Insulation Manufacturers Association, they’ll assure you that fiberglass or mineral wool is definitely your best choice for insulation.

Spray foam
From a performance standpoint, the best type of insulation is spray foam. There are two types; closed-cell and open-cell, aka 2-lb and ½-lb, respectively. They have insulation values of approximately R-6.5 and R-3.6 per inch, respectively. When installed properly, both types of insulation will fill all of the nooks and crannies and make for a perfect air barrier. When air can’t move through it, you have zero heat transfer through convection. Oh, and by the way, Icynene® is a brand name of open cell foam.

With closed-cell foam, you also get a moisture barrier at over 2″ thick. Because of this and the higher insulating value per inch, most foam insulation used in Minnesota is closed-cell. To tell the difference between the two, try poking it with your finger. You can easily poke a hole in open cell foam, but not closed-cell foam. That stuff is way too hard.

 

The big downside to either type of spray foam insulation is the cost. It’s expensive stuff, and it shouldn’t be installed by the DIYer. Of course, that’s not to say it can’t be done, it just shouldn’t be done. Professionals already have a hard enough time getting it right. Check out this article for more on that topic: Avoiding Problems With Spray Foam. The image below shows a botched spray foam installation at the rim joist of a new-construction home that I inspected.

A concern with spray foam insulation is the off-gassing of toxic poisons. I’m no expert on that matter, so I won’t discuss. Just be aware that it’s a concern, and do your own research. After conducting my own research, I concluded that I was comfortable putting it in my own home.

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Insulating a Post Frame Home Crawl Space

One of our clients has been erecting a post frame home in Colorado Springs, which is over a crawl space. Here is our discussion in regards to insulating the crawl space.

“While I have your ear, I had asked you a question earlier about getting the code required R30 in the 2×6 floor joists of my raised floor. I looked into your suggestion of spray foam and I got some quotes from local companies and I was shocked! One company quoted me $16,000 to do 3″ in the floor and walls with some performance charts showing that the 3″ would satisfy the code (I’m a bit skeptical). I got another general quote of $1.10/board foot and that it would take 5″ (i.e. $5.50 / sq ft)  or $12,650 just for the floor. The second company did suggest though that El Paso county allowed the R30 around the crawl space perimeter and no insulation in the floor… which leads me to my question…

What would be your thoughts of a non-vented crawl space using something like 15 mil plastic on the ground and up the sides the 18″ to the floor and the R30 spray foam from the ground to the floor level?  I could get that done for around $2500. I’m still haven’t completely decided if I will used dense pack cellulose or BIBs for the walls but I’m pretty sure I don’t have the budget for spray foam in the walls.”

Mike the Pole Barn Guru Responds:

When I moved to Oregon from Eastern Washington in 1979, I was amazed at how different the construction techniques were from what I had grown up with. Eastern Washington was the land of full basements, whereas Western Oregon was predominately crawl spaces. The typical crawl space would have 6 mil black visqueen draped down the sides of the foundation and covering the ground, with R-19 unfaced batts used to insulate directly beneath the floors.

A variant of this was to use the crawl space as an air plenum, eliminating the need for heat ducts, and placing the unfaced insulation against the foundation.

This variant is basically a very slight spin away from what you propose to do.

Performance charts always frighten me as they general require some hocus pocus involving dead air space. Closed cell spray foam is R-7 per inch, so a claim of three inches in a system making R-30 sounds bogus unless the balance of the cavity is going to be filled with something like unfaced fiberglass batts. There is no question about closed cell spray foam being expensive, even the work I had done when we added the elevator shaft on the back of our home ran $2.80 per square foot for four inches thick.

Personally, I have no issues with what you propose to do and would probably take it a step further and utilize the principles of Frost Protected Shallow Foundation insulation below the base of my wall steel. https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/.

This entry was posted in Insulation, Pole Barn Questions, Pole Barn Design, About The Pole Barn Guru, Pole Barn Homes and tagged , , , on by .

How to Insulate My Post Frame Garage

How to Insulate

I fear “how to insulate my post frame (fill in the blank)” is going to be my most answered topic for the next decade. Energy efficiency is the “hot” topic right now and sadly there are more folks trying to solve what they already have, than there were those who planned for it correctly in the beginning.

Reader ERIC in FENELTON writes:

“Hello, I am wondering what the best and most cost effective way to insulate my post frame garage would be. I recently erected a 32’x48’post frame garage with glulam posts on 8’ centers, girts and purlins on 2’ Center’s, trusses on 4’ centers with 1’ overhangs with center soffit and ridge vent. Walls and roof are steel with double bubble between purlins and roof steel and tyvek between hurts and the wall steel. I will be building a wall to separate one of the bays as a metal shop for welding and fabricating. This will be the only bay that is heated and is 32’x21’. I am on a budget but my biggest concern is moisture. I installed the tyvek and double bubble hoping to positively effect the problem but am still hesitant to put fiberglass in the
walls but spray foam is out of my price range. I have seen some people cut 1 1/2” foam board to fit between the wall girts and either stop there or then frame traditional walls between the posts and add R13-R19 faced insulation. Is this an adequate way to insulate and will the foamboard keep moisture from the fiberglass? I will definitely be framing between posts and then covering with painted OSB regardless of the insulation method I choose. Also, I was leaning toward using fiberglass batts in the ceiling and then using the white liner steel under the trusses. They are 2×6 top and bottom cord trusses and rated for a ceiling. Fiberglass in the ceiling gives me the same moisture
concerns however. So I guess my question is, now that you know about my building, what is the best abs most cost effective way to insulate the portion of the building and avoid moisture? Spray foam is out of the question due to costs. I have been doing a ton of research but get different answers everywhere I go. Any help will be greatly appreciated. Thank you.”

Mike the Pole Barn Guru
As long as the Tyvek is well sealed, you will not be gaining moisture from the outside on the walls. What you need to create is a dry wall cavity. Completely fill the wall with unfaced fiberglass (you might consider using BIBs https://www.hansenpolebuildings.com/2011/11/bibs/)
and cover the interior of the wall with a well sealed vapor barrier (clear visqueen will do nicely). Cutting foam board is an exercise in
futility unless you can figure out how to completely seal it, if you
stop at this point.

For your ceiling – there is a good chance you will experience
condensation on the underside of the steel ceiling liner panels. With
your vented eave and ridge, blown in fiberglass is probably the best
answer. If you do not have raised heel trusses, you should probably look
at spray foaming the first couple of feet of the ceiling area in order
to reduce heat loss from not being able to gain full thickness of the
fiberglass.

This entry was posted in Insulation, Pole Barn Questions, Roofing Materials, Pole Building How To Guides, Ventilation and tagged , , , , on by .

Condensation Solutions, A Ceiling the Right Way, and Timing

Advice about condensation, ceilings done right, and the timing of questions

DEAR POLE BARN GURU: My deck roof is metal panels on 2×4 purlins, rafters are 2×6, like a pole barn. I am enclosing it, and need to stop the condensation. I spray foamed it with closed cell, but there is some condensation on the foam in a few places. It will be covered with drywall. Would a 6 mil plastic vapor barrier on the conditioned side work? MICHAEL in FRAZIER’S BOTTOM

DEAR MICHAEL: Provided you are able to reduce the moisture content within the building so as no vapor is being trapped between the vapor barrier and the foam, it should take care of the problem. In all reality, as long as you have no holes in the gypsum drywall, once it is painted you should have eliminated the problem of condensation against the insulation.

Now getting to the real problem – you have too much moisture in your building. If you did not place a well sealed vapor barrier under your concrete slab floor, you need to seal it. Walls also need a vapor barrier (without holes) on the conditioned side to prevent moisture from passing through.

 

DEAR POLE BARN GURU: I have a 40 x 80 pole barn with 8 foot truss spacing. I will be installing faced rolled insulation between each truss. What is the recommended ceiling product to install on the inside? Wood, metal, that will be lightweight and easy to install?? Thanks JEFF in SYCAMORE

DEAR JEFF: I see problems in your future….

Installing a ceilingFaced insulation is the absolute wrong product to use for insulating your ceiling. Any insulation placed at the truss bottom chord level should be unfaced. The best bet would be to blow insulation in above the finished ceiling.

In any case, you must adequately vent the attic space.

Now, on to the ceiling.

 

I am hopeful you have trusses designed with a minimum of a five psf (pounds per square foot) ceiling load, with 10 psf being even better. Confirm with your RDP (Registered Design Professional – architect or engineer) who designed your building, however 2×4 #2 ceiling joists at 24 inches on center between the bottom chords with joist hangers should adequately support a ceiling.

My choice of ceiling product?

5/8” Type X gypsum wallboard. It is affordable, weighs under three psf and provides fire resistance.

 

DEAR POLE BARN GURU: I’m putting up a building with a 3/12 pitch single sloped roof. radiant reflective polyethylene, vapor barrier insulation between the purlins and the metal roof sheathing. Probably rock wool batts under the 1-3″ draped barrier. Do you think the roof has to be vented, and how would this work? CHRIS in BROOKLINE

DEAR CHRIS: Yes, it would need to be vented and it is my feeling you are going about this entirely in the wrong direction. Your question is well timed, as I have just written an article on how to properly insulate between purlins, which will be posted soon. The basic gist is your best solution is to use closed cell spray foam applied directly to the underside of the roof steel.

 

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How to Properly Insulate between Roof Purlins

How to Properly Insulate Between Roof Purlins

Efficient climate control is becoming the buzz term for post frame construction. A challenge occurs when clients look to insulate between their roof purlins.

Reader JOHN in COVINGTON writes:

“I am building an all wood pole building. The purlins are 2x8s. I want to insulate the walls and up at the purlins to keep as much usable space as possible with an insulated building. How do I insulate and properly vent between the insulation and the underside of the plywood roof underlayment. If I use R19 it is 6 inches so there would be 2 inches of space between the insulation and the wood. Do I use something like a house bird block at each end of the building for each purlin space?”

Mike the Pole Barn Guru Writes:

The best solution lies in creating an unvented roof

It is quite possible to design an unvented insulated roof assembly which performs well, as long as you get the details right. In recent years, most building codes have begun to allow the construction of unvented insulated sloped roof assemblies. Many such roofs have failed over the years, however, so don’t get creative. Follow the rules.

For sake of brevity, I will limit this discussion to only as it pertains to post frame buildings with widely spaced trusses and purlins on edge.

First of all, you can’t use air-permeable insulation (for example, fiberglass batts, mineral wool batts, dense-packed cellulose, or blown-in fiberglass) to insulate an unvented roof assembly unless the roof assembly also includes a layer of air-impermeable insulation (spray polyurethane foam) directly below the roof steel or sheathing.

The 2009 IRC (International Residential Code) defines air-impermeable insulation as “an insulation having an air permeance equal to or less than 0.02 L/s-m² at 75 Pa pressure differential tested according to ASTM E 2178 or E 283.” Although spray foam insulation and rigid foam insulation meet this standard, fiberglass batts and dense-packed cellulose do not.

If you want to use just one type of insulation in unvented bays, you are limited to spray polyurethane foam. Another possibility, of course, is to build your roof with structural insulated panels (SIPs), which in most cases is cost prohibitive.

The code restrictions on the use of air-permeable insulation between purlins were developed to prevent the purlins or roof sheathing from rotting. When fiberglass batts are installed in unvented bays, the batts allow moist indoor air to reach the cold steel roofing or sheathing. That leads to condensation or moisture accumulation, followed eventually by rot. Since spray foam prevents air movement, it almost eliminates this problem.

It’s important to note, however, recent research suggests closed-cell spray foam is much less risky than open-cell spray foam in this location.

To summarize, there are really two practical ways to build an unvented roof assembly:

Install closed-cell spray foam against the underside of the steel roofing or roof sheathing, and no other type of insulation. Be sure the thickness of the spray foam is adequate to meet minimum code requirements. Remember open-cell spray foam is risky in all climate zones, and if open-cell spray foam is installed in this location in a cold climate, the underside of the cured foam must be covered with gypsum drywall which has been painted with vapor-retarder paint. Vapor-retarder paint is ineffective if it is sprayed directly on the cured foam.

Install a layer of closed-cell spray foam against the underside of the steel roofing or roof sheathing, and fill the rest of the purlin cavity with an air-permeable insulation. This type of assembly is designed to dry to the interior, so the assembly should never include an interior polyethylene vapor barrier.


 

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Post Frame Insulation in the South

Post Frame Insulation in the Hot and Humid South

Reader RICK in LUCEDALE writes: “Dear Pole Barn Guru, I am in the planning stage for designing a post frame house. I live in a “Hot and Humid” climate in the southern US. Joseph Lstiburek, a building science guru, suggests having an unvented roof for my climate zone with the HVAC in the conditioned air space. The metal roof would have a layer of single bubble vapor barrier under it with BIBS insulation installed in the roof purlins. The walls would have a building wrap behind the metal siding and BIBS insulation. The walls would have a vapor barrier between the drywall interior and the insulation. Does the roof assembly need another vapor barrier on the inside? What happens at the intersections between the single layer bubble vapor barrier, the building wrap, and the sub slab vapor barrier? I assume I can use non venting closure strips at the ridge and closed non venting soffits? What size should the purlin be to get an R value of 30+ ? What would be your recommendations? Thanks.”

Mike the Pole Barn Guru writes:

Unless your post frame house will have extremely large purlins, you will not be able to get sufficient depth of insulation using BIBs. Energystar.gov recommends roof insulation values of R-30 to R-60 for your part of the country. BIBs provides an R value of 4.23 per inch, so to achieve a minimal value of R-30 would require at least a 2×8 purlin and would realistically not provide the insulation value I would personally be looking for.

I’d be looking at the use of closed cell spray foam insulation, which would give you R-7 or better per inch of depth. It also completely seals everything, eliminating the need for a reflective barrier below the roof steel. With 2×6 purlins, one could spray eight inches of foam completely filling the space between the purlins as well as covering the underside of them (and the underside of the roof truss top chords).

The goal here is to achieve a complete envelope seal of your building’s perimeter. You will not want a vapor barrier between the living space and the attic. The building wrap is not a vapor barrier, it is a weather barrier. The vapor barrier on the inside of the walls should be installed so as to be sealed into the roof plane spray foam and sealed tightly to the slab on grade (although I prefer living over a crawl space).

Soffits should be non-ventilated and closed cell foam closure strips should be used at the top and bottom of all steel panels.

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Insulating an All Wood Gambrel Barn

A reader writes: “Dear Guru.I have an all wood gambrel style pole barn that I’m converting to a shop.  I’ve installed forced air heat and am getting ready to insulate.  My exterior walls are Tyvek wrapped osb and vinyl sided.  I am wanting to use rigid board to help deter rodent nesting.

  My questions are: for the walls should I cut and fit 1 1/2 inch board to fit all of the spaces between my girts before I layer rigid over the girts or can I layer over the girts to start?   The ceiling I was planning on installing 2″ rigid on top of the 2×4 truss bases and then applying a closed cell poly “Prodex” brand white faced on the bottom leaving the 3 1/2 inch air gap between the two. Prodex is claimed to be r16 and the rigid r10. Or is there a more suitable way to do the ceiling like cutting board to fit between said trusses and using Prodex on bottom with no air gap?  

 Thank you for your help.  I’m finding hundreds of articles and advice on metal buildings which mine is not and trouble finding a solution for my project.  Oh, and I live in northern Ohio”

Good move having Tyvek in your walls to prevent weather from seeping into your insulation cavity. If your walls are tightly framed (which they should be) the possibility of rodents getting into your wall cavities should be zero. Cutting and fitting insulation board to fit between framing members sounds like a mountain of labor, as well as pretty near impossible to be able to get a tight fit against every stud. I’d be inclined to use either closed cell spray foam insulation or BIBs insulation for walls.

Prodex is a radiant barrier and your chances of getting a measurable R value out of it more than one and change is not good. In a thorough 2010 study by the Canadian National Institute for Research in Construction, their conclusion: In a perfect state (with no dust on the surface), a radiant barrier with an air gap increased the efficiency of insulation in a wall by 10%. In other words, if the wall was already R6, adding ‘miraculous’ foil bubble wrap added .6, for a total of R6.6.

The best way to insulate your ceiling is to blow in cellulose or fiberglass to at least R45, if not R60. Do not place a vapor barrier under blown in insulation. Make sure the attic space above the insulation is adequately vented.

 

Mike the Pole Barn Guru

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Spray Foam Advantages Over Batt Insulation

Once again – confession time. I’ve never personally used spray foam insulation.

My oldest stepson, Jake, teaches high school chemistry and physics. He is one smart dude, as he has a master’s degree. When he added onto what was formerly his grandparent’s home, in the Browns Valley, MN area, he utilized closed cell spray foam insulation.

Not only is Jake smart, but he is also frugal, which tells me he did his research and compared costs of not only the original installation, but also savings over time.

Polyurethane foam insulation is available in closed-cell and open-cell formulas. With closed-cell foam, the high-density cells are closed and filled with a gas which helps the foam expand to fill the spaces around it. Open-cell foam cells are not as dense and are filled with air, which gives the insulation a spongy texture.

Polyurethane and isocyanate foams are applied as a two-component mixture which comes together at the tip of a spray gun, and forms an expanding material. While open-cell foams typically have R-values of 3.5 per inch, closed-cell foams can attain R-values of 7 per inch. Closed-cell foam is very strong, and structurally reinforces the insulated surface. By contrast, open-cell foam is soft when cured, with little structural strength. However, it provides superior sound resistance and allows timber to breathe. It is also fire-resistant and won’t sustain a flame.

insulation-rollSpray foam insulation costs more than batt insulation, but it has higher R-values. It also forms an air barrier, which can eliminate some other weatherizing tasks, such as caulking. This plastic insulation goes on as a liquid and expands to fill the available space, sealing all gaps and cracks and stopping any air leaks (This can also keep out bugs or other vermin). Another advantage is foam can fill wall cavities in finished walls without tearing the walls apart (as required with batts). It also provides acoustical insulation and increases structural stability. When building a new post frame building, this type of insulation helps reduce construction time and the number of specialized contractors, which in turn saves money.

The cost can be high compared to traditional insulation; however, open cell foams provide a better economical ratio. Open-cell foam is $1 to $1.20 per sq. ft. while closed-cell foam is $1.75 to $3 per sq. ft. (for a 2-by-4-framed wall). Both require professional installation.

Here is an earlier example of the investments into each: https://www.hansenpolebuildings.com/2014/02/insulation-foam-fiberglass/

Although for moisture control closed-cell foam is non-porous, open-cell requires a vapor barrier; however, the added cost of closed-cell foam may not be as advantageous as vapor barriers are usually required by building codes, regardless of the type of insulation used. Also, closed-cell polyurethane insulation levels can drop over time as some of the low-conductivity gas escapes and air replaces it in a phenomenon known as thermal drift.

In summary, DIY people use fiberglass as it is readily available, maintains a reasonable price ratio and is easy to install. Although it is not as easy to sustain the higher performance required by today’s insulation standards over time. It is also a health hazard. Most tract homes also use fiberglass insulation for the same reasons. However, the installation experience of the contractors can improve the overall performance.

Higher-end tract homes and custom homes tend to use the cellulose and foam solutions. They provide a superior insulation level and a number of other advantages, including air and vapor blocking, noise reduction and insect minimization.

As with all things, you get what you pay for and you can pay up front or pay later. There is no shortcut to energy efficiency and saving money.

We will be adding an elevator shaft to our own post frame building home later this summer. Although it is not a large footprint area, it will be over 30 feet tall and keeping it the temperature of the rest of the building will be a high priority – so I will be investigating spray foam myself.

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Insulation Between Roof Purlins

From the number of “Ask the Pole Barn Guru Questions” I receive and the new pole buildings I see being constructed, climate control is of very high importance. When I first entered the post frame industry 35 years ago, no one cared about it as virtually all ‘pole barns’ were farm buildings or small private garages. Not the case anymore! Pole Buildings run the gamut from heated shops, airplane hangers with living spaces and custom designed homes or year around lake cabins.

For heating and cooling, it is most efficient to have to control the least amount of space. Reducing the height of the area to be heated, will result in more comfortable temperatures in the area humans typically occupy.

Installing a ceilingThis area can be reduced by finishing off the ceiling (with my personal preference being gypsum wallboard) and blowing in insulation above the ceiling – along with having a properly ventilated attic space. To give a rough idea of the volume of space differentials on a 40 foot wide by 60 foot long by 12 eave height building, having the most typical roof slope (4/12), about 25,000 finished cubic foot of area is to be conditioned with the ceiling, as opposed to nearly 34,000 cubic feet otherwise.

A significant amount of some sort of fuel is going to be used to heat or cool the extra one-third volume of space!

Some people prefer to insulate between the building roof purlins, however this can be fraught with potential challenges if not done properly.

The easiest solution, however possibly not most cost effective, is to utilize spray foam insulation. For most people, this is just not an affordable solution (read more at: https://www.hansenpolebuildings.com/2014/02/insulation-foam-fiberglass/).

Unfaced (typically fiberglass) insulation can be placed between the purlins. The purlin dimensions can be increased to allow for thicker insulation – which will be required (in most cases) if energy code requirements need to be met. By Code, airflow must be provided above this type of insulation. As roof purlins run the longitudinal direction of the building, 2×4 material can be placed flat on top of the purlins, running from eave to ridge. In order to utilize the space created by these 2x4s, the eaves and ridge will need to be ventilated.

A vapor barrier will need to be installed above the air flow area, if the roof is through screwed steel over purlins. An ideal solution would be a reflective radiant barrier, with another flatwise layer of 2x4s placed on top of it (in the same direction as the roof purlins). This creates another dead air space which improves the efficiency of the reflective radiant barrier.

Seriously looking to insulate between roof purlins while conserving energy? Design it right in the beginning!

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Dear Guru: Why Vapor Barrier?

DEAR POLE BARN GURU: I constructed a pole building with the help of Iowa based Amish group. They put up the main structure including metal roof. Due to city codes, I enclosed the 40x60x12 structure using 1/2 osb, house wrap and then vinyl siding. I want to use paper faced 4x8x4″ Styrofoam sheets on the walls, and roll insulation for the ceiling. My question is, do I use a vapor barrier on the walls after putting in the Styrofoam or none at all? And for the ceiling I would assume I would attach a vapor barrier to the bottom side of the trusses and lay the R-25 unfaced insulation on top of that. I have ridge vent and soffit vents. Thanks for your help! Curt in Center Point, IA DEAR CURT: For a properly performing system, your building should have a vapor barrier on the inside of all walls. The paper facing on the Styrofoam™ panels should be a vapor barrier. In order to perform properly, you need to make sure all edges and joints are tightly sealed, to prevent moisture from entering the wall cavity.

A vapor barrier should NOT be placed across the bottom of the roof trusses. If your building has steel roofing, I am hoping some sort of thermal break (like a reflective radiant barrier or similar) has been installed between the roof purlins and the roof steel, otherwise you are in for a plethora of problems. Warm moist air from your building needs to be able to pass through the ceiling and into the non-conditioned dead attic space, where it can be properly vented out of the ridge vent. You also should consider a greater R value in the attic. According to the North American Insulation Manufacturers Association https://www.naima.org/insulation-knowledge-base/residential-home-insulation/how-much-insulation-should-be-installed.html a minimum of R-38 should be installed in Iowa.

Mike the Pole Barn Guru

Dear Pole Barn Guru: We had hail damage to a post frame office building last Summer. Several months prior to the storm we had the side walls spray foam insulated (closed cell) and then framed and dry-walled. We have finally settled up with the insurance company and are ready to “re-skin” the building. The spray foam insulation was a significant expense and if we take off the metal siding the insulation will come off too. Here is my question: Can we simply install another layer of 29 gauge metal siding over the existing siding? Or can we fur out and install a different type of siding? Your input would be greatly appreciated!   KEN in Ft. Collins, CO

DEAR KEN: Although hail damage to steel siding and roofing is unusual, you have now found the downside to spray foam insulation applied to the inside face of it. If you place furring strips on the outside of the existing siding, you are most likely going to end up with the siding on the eave sides extending past the typical steel roof overhangs provided with most pole buildings. Plus, anything other than pre-painted steel siding is likely to come along with a lifetime of having to maintain it. In all probability, your best solution may very well be to install siding of the exact same profile over the existing steel. Screws will need to removed from each panel as you work your way down the wall, and replaced with screws of a larger diameter, as well as longer – in order to properly hold both layers of siding in place. With some patience, the results should turn out satisfactory

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