Tag Archives: condensation control

Skylight Width, Gable Fans, and Post Spacing

This Wednesday the Pole Barn Guru answers reader questions about the standard width of a skylight, gable fans for ventilation, and post spacing for a roof only building.

DEAR POLE BARN GURU: What is the standard width of a skylight on a pole building?

ROBERTA in DAKOTA

DEAR ROBERTA: In most instances pole building skylights are fiberglass or polycarbonate panels with same configuration as 3′ width net coverage steel roofing. For some extended reading on skylights please visit: https://www.hansenpolebuildings.com/2012/01/skylights/

 

DEAR POLE BARN GURU: Just completed a 36×84 x 14′ high pole building. Self designed. I sheeted the roof, both gable walls, and the front wall for shear and strength using 1/2″ cdx. I used ice and water shield under the roof and house wrap on the walls. Concrete slab with 6mil vapor barrier underneath. No insulation. Also, no ventilation. Noticing I need ventilation, before things get moldy etc. I’m considering putting a 24″x24″ 5000cfm powered gable fan on the east side, and a 24″x24″ intake vent on the west side. Would this be adequate to keep condensation and moisture at bay? TODD in PORT ORCHARD

DEAR TODD: Lack of ventilation is a harbinger of future condensation problems with well-sealed buildings. Your building has roughly 51,000 cubic feet of interior air volume, meaning a 5000 cfm powered fan will turn your air roughly every six minutes (or 10 times per hour). This should be adequate, however a greater capacity might be worth considering. You will also want to look at actual NFVA (net free ventilation area) of your intake, as lack of intake area can restrict performance of your exhaust fan.

 

DEAR POLE BARN GURU: Hi, My name is Joe. I’m trying to build a pole barn with in an area of Washington that has a snow load of 15 PSF.  The building is 24′ wide by 38′ deep with 14 feet clear height. no side walls. Seems like spacing varies quite a bit from 8 ft to 12ft. Thought I would see what u would suggest for this?  I was thinking about doing 12 ft or maybe even 10 ft.  Any thoughts would be much appreciated? JOE in WASHINGTON

DEAR JOE: I would look at doing bays of 12′ – 14′ – 12′ first, however you should discuss options with whoever is going to engineer your building plans. Depending upon what you will be using this building for, it may be less expensive to cover one or both 24′ endwalls from roof to ground, than to have a roof only. A Hansen Pole Buildings’ Designer will be reaching out to you to discuss your needs, as we have provided roughly 1000 fully engineered post frame buildings to our clients in Washington State.

Condensation Control, a Bottom Track, and New Steel

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

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

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

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

 

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

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

Your sliding door metal girts should look like this:

They are installed with slots down (towards ground).

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

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

 

DEAR POLE BARN GURU: Hi there,

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

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

I want to put metal siding and roofing on it.

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

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

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

Thanks, BRYCE in SPOKANE

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

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

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

Spray Foam, Second Floor, and Bending Posts

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

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

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

 

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

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

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

 

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

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

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

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

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

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

 

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

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

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

 

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

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

 

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

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

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

Thank you, TERRY in WILSONVILLE

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

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

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

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

 

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

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

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

 

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

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

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

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

Ceiling Insulation, Drafting Capabilities, and 24″ On Center Framing

This week the Pole Barn Guru answers reader questions about “ceiling insulation” for a roof rebuild, the capabilities of our drafting and proprietary pricing program, and “what percentage of pole buildings are 24″ on center?”

DEAR POLE BARN GURU: The birds have destroyed the front half of the ceiling insulation in our 40 x 60 pole building. We need a new roof and we plan to take out all the insulation when the roof is done. We don’t know what else to do because if we leave the insulation in the back half of the ceiling, the birds may destroy that also. What do you think? SHARON in STERLING

DEAR SHARON: Typically when I hear people talk about birds having destroyed pole building insulation I think of what is commonly known as Metal Building Insulation. Usually this is a thin layer of fiberglass with a white vinyl face – and once birds get started into it, there is no turning back https://www.hansenpolebuildings.com/2018/09/spot-problems-with-this-pole-barn-photo/

If you are doing a reroof, to control condensation your should look at ordering roof steel with a factory applied I.C.C. https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/

 

DEAR POLE BARN GURU: I was curious on what program you use to make your plans? Does it do take off and quotes with the drawings? Can you design the interior also the exterior to make a shouse? TIM in NORFOLK

instant pricingDEAR TIM: Always a pleasure to hear from a “lumber guy”. Our blueprints are actually drafted individually on AutoCAD, however we are gradually transitioning to where most fairly straightforward work will be automated from our trademarked and proprietary “Instant Pricing” system. We searched everywhere trying to find a computer program able to actually accurately do a structural analysis of post frame buildings and found none existed. We created our own and added to it abilities to do real time quotes for any climactic condition and anywhere in America. Our program does quotes, invoices, material takeoffs, creates purchase orders and interfaces with our client data base.

While it can do interior walls, we opted to create a full service program for shouse and barndominium plans with a real person interacting via screen sharing so clients can watch their homes appear before their very eyes from the comfort of their homes.

 

DEAR POLE BARN GURU: What percent of pole barns are on 24″ centers? BRUCE in SXARTZ CREEK

DEAR BRUCE: There are numerous components of post frame (pole barn) buildings often placed 24 inches on center. Among these could be wall girts, roof purlins, sometimes roof trusses (most often seen with shingled roofs), floor joists or floor trusses over crawl spaces, basements and for second or third floors. One of fully engineered post frame building design’s beauties is there is no obligation to be at a specific spacing and materials can be utilized for their full structural capacities – making them extremely cost efficient.

 

 

Decisions, Decisions – Vapor Barrier for a Post Frame Steel Reroof

Decisions, Decisions – Vapor Barrier for a Post Frame Steel Reroof

There are few reasons to replace an existing post frame building’s steel roof, as properly installed it should last a lifetime. Among these reasons could be:

Tired of Existing Color
Old roofing was nailed on
Tree fell through roof

This last one actually occurred to our shouse (shop/house) when I lived in Northeast Washington!

Loyal reader and Hansen Pole Buildings’ client MIKE in COUPEVILLE writes:

Reflective Insulation“I am currently re-siding/re-roofing an existing pole building in order to match the exterior of the building I recently purchased from you.  This building is roughly 32 x34 and the roof purlins are 2×6 on end roughly every 2 feet.  I’m using Fabral’s grand rib 3 29ga for the roof and it will have fully vented soffit overhangs and a vented ridge cap.  I am trying to figure out what I’m going to do for at least a vapor barrier under the roof steel, I see you seem to recommend foil faced bubble insulation but that is not very common in my area.  I am seeing a lot of people using lamtec wmp-vrr (fiberglass insulation with a poly backing)  3″ thick and I believe they lay these wide rolls on top of the purlins and then place the metal roofing on top of that then screw down the roofing compressing the fiberglass insulation between the metal roofing and the purlins.  Have you seen this style of insulating before?  Do you think it is an acceptable way of doing it?  I see as killing two birds with one stone.  I may be insulating this shop in the future so if I do then the roof is already insulated plus I believe it acts as a vapor barrier which is the main reason to do it as I don’t want any condensation dripping down on the inside of the shop.  I live in the Seattle area if that helps to know what my climate is like.  Thanks in advance for your input.” 


Mike the Pole Barn Guru responds:

Our recommendation would be to order your roof steel with factory applied I.C.C. (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/).

Metal Building Insulation (fiberglass with a vinyl facing) is a decent condensation control, provided all of the seams are tightly sealed. It is a pain to work with, provides very little effective insulation value and makes your roofing pucker outwards between purlins https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/.

If it is too late for an I.C.C. then the radiant reflective barrier (https://www.hansenpolebuildings.com/2017/05/effective-reflective-insulation/)

 is probably your best option.  Order in six foot width rolls to minimize seams and make sure to get a product including a tab along one edge with an adhesive pull strip attached.

How Best to Use Metal Building Insulation

How To Best Use Metal Building Insulation

Loyal reader ANDY in SOUTH CAROLINA writes:

“ I read with interest the article “What house wrap is good for” on your website and would like to include house wrap on a pole building I’m currently planning to build in the upstate of South Carolina.  Typically builders in that area simply use 3” polypropylene faced fiberglass insulation between the wall girts and steel siding. My situation is a bit different than most I have seen in that my single story building will be 1500 sq ft total, with 900ft dedicated to garage and shop space, and 600 ft dedicated to a guest apartment. If I were to place house wrap between the girts and steel as I believe you recommend, could the 3 inch faced insulation simply be placed on the inside of the girts for the garage space, and significantly more fiberglass insulation used around the apartment – inside deeper cavities of flush walls?  

Thank you.”

For those of you who need to know, here is article referenced by Andy: https://www.hansenpolebuildings.com/2012/11/house-wrap/


Surprisingly there are a lot of builders who “sell” people on how valuable a benefit Metal Building Insulation is. Long time readers may recall my personal adventures with it: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation-in-pole-buildings-part-i/

Three inch thick Metal Building Insulation makes for a very poor return on investment as every time it crosses a wall girt it gets compressed pretty well to R-0. If lucky, one might net an R-3 or so out of it. It also tends to cause steel siding to pucker outward between girts. Properly sealed, it does make for a decent condensation control.

My recommendation would be to place a well-sealed WRB (Weather Resistant Barrier) between all wall framing and siding. Use commercial style bookshelf girts to create an insulation cavity https://www.hansenpolebuildings.com/2020/05/how-to-install-bookshelf-girts-for-insulation/. Use unfaced batt insulation with a minimum 6 mil clear visqueen vapor barrier on the inside. For what you would pay for three inch Metal Building Insulation, you can completely fill your insulation cavities.

Quonset Hut Homes

With the proliferation of barndominiums, shouses and post frame homes there is always someone looking for a cheaper answer. I have found cheaper generally gets me exactly what I paid for – cheap. Well for some, cheap may be living in a Quonset hut.

Considering a Quonset building for your new home? Consider resale value – there are very few people who want to live in a Quonset!

You may have heard Quonsets advertised on television, radio, online (even on Ebay) and in  back of Popular Mechanics.

I came across this query from a gentleman from Wake Forest, NC, “I have found some really good deals on the local craigslist from private individuals who have bought them and never put them up for one reason or another.” He wanted, “…to hear anyone’s input, good or bad. Yes, there are a lot of horror stories out there about poor schmucks that got hosed trying to buy from some less-than-scrupulous purveyors of these structures, but like I said, I plan on purchasing from a private individual who already has it in his possession.”

Now all of this got me thinking, so I started my research. It turns out Quonset huts were named for where they were first manufactured – Quonset Point, Rhode Island. First built for our Navy in 1941, as many as 170,000 Quonset huts were produced during World War II.

According to Wikipedia, “The erection of Quonset huts has been banned in the US state of Alaska for many years due to so many already being in the state and the majority of those falling into disrepair and becoming environmental hazards.”

I’ve never been involved in construction of a Quonset hut myself, as my background is in conventional stick frame and pole buildings. Due to this, I relied upon the experiences of four people.

When I was a post frame building contractor, Jay and his crew subcontracted labor on several pole barns we sold. Jay also did concrete work. On his own, he contracted to do concrete and assembly of a Quonset for a golf course driving range not far from me. This building was 40’ x 60’ and they worked on it every day for a month. Jay’s comments were anything but positive about concrete requirements and he said, “I’ve never seen and installed so many bolts in my life”. Of course when up and done, it had no endwalls, so those had to be constructed, and round walls precluded anything from being attached to them (not to mention it was near impossible to insulate.)

This insulation issue brought me to a comment from a Bob in Paisley, PA, talking about a local feed store, “The feed store has had issues with theirs and the original owner said it was a bad choice. They had a company come in and spray adhesive type insulation to the entire inside. As the metal expands and contracts portions of the insulation failed to follow the same rates which in turn resulted in chunks of reflective insulation falling from the ceiling area. Condensation and drips formed after the insulation fell.”

A second experience was told to me by one of my oldest daughter Bailey’s friends. Her friend’s father bought a Quonset for a garage. The pieces for it lay in a pile next to their house for several years, untouched. He finally sold it.  I can only surmise from comments it was quickly discovered to be far too much work to erect it, once purchased.

Online, I found this post from a gentleman who was actually espousing how wonderful Quonset buildings are:

“One of the few frustrating things about our Quonset is water leaks. The shell itself is engineered to be completely watertight. But, as with most well-planned projects, reality has a way of challenging the ideal. After checking all the bolts and tightening a few, we were able to seal all but a couple of leaks. The remaining few were due mainly to small tears in the metal at the bolt holes caused by over-stressing the skin in an effort to line up holes. After we made these mistakes a couple of times we realized our errors and corrected them. But the damage was done. 

Our biggest problem was sealing leaks at the base, where the shell meets the concrete and where it ties into the base plate. We were advised to fill the void created by the shell meeting the channel with concrete, which we did. We also used a heavy application of caulking between the base plate and the concrete. In spite of this, when it rained, we had an indoor pool. We then caulked all around the concrete where it met the metal. It still leaked. We then coated the whole area with water-stop concrete, a kind of latex/cement material that is supposed to seal concrete and bond to metal…it still leaked. We caulked again…to no avail.”

Lastly, one of our former Building Designers, Paul, related from his personal history as a Quonset salesman. His words were, “Less than 50% of the ones sold, are ever constructed.”

My summation is – even if they were easy to construct, Quonsets generally come in a single color – galvanized. They are difficult to insulate, with condensation control certainly being an issue. The purchase price often does not include endwalls, and certainly not doors (and sometimes not even delivery). And, speaking of doors, how do door and window openings work with curved (or even extremely high ribbed) sides? In Bob’s words, “Unless you get one of the tall ones you end up with an area along each of the sidewalls that becomes unusable except for collecting junk on the floor. Then it can be a head banger along the wall whenever you walk directly toward it while looking down for the junk.”

If anyone has a great, glowing story about Quonset huts, I’d love to hear it, I really would.  Because so far, I’m not impressed.  But I am always willing to listen to….”the other side of the story.”  Obviously I’m looking for objective evidence from those using quonsets…not just those selling.

Condensation Control, Home Plans, and Grade Changes!

DEAR POLE BARN GURU: If I put double bubble under metal on roof for condensation control, then insulate bottom chord of trusses with white vinyl faced insulation , will this create a problem if I ventilate attic space ? Thanks. SCOTT in DUNLAP

DEAR SCOTT: You actually have several things going on here. First, single bubble reflective radiant barrier will do everything double bubble will, at a far lesser investment. The difference in the minimal R value is a fraction of one! Your building ceiling should not have an additional vapor barrier, you want the moisture from inside the building to be able to migrate through into the ventilated attic space. Blowing in an appropriate thickness of fiberglass or cellulose insulation will be far more effective, probably less expensive and will allow the moisture through. Make sure to have adequate intake at the eaves and exhaust at the ridge to be able to properly vent the dead attic space.

DEAR POLE BARN GURU: Hello!

Do you all also finish the interior of pole barns if we want it to be a home or would I contract that separately?

Thanks! TIFFANY

DEAR TIFFANY: Thank you for your interest in a new Hansen Pole Building. We provide the custom designed plans, materials delivered to your site and assembly instructions for the shell and load supporting portions of your new building only. Any interior walls and/or interior wall finishes would be up to you to contract for.

 

 

DEAR POLE BARN GURU: Can I build a pole building home in the side of a hill, where the back will be below grade and the front above. RICK in CLEAR LAKE

Post Frame HomeDEAR RICK: Most certainly you can. I have a post frame building on the back of our property outside of Spokane, Washington. The site has 12 feet of grade change across the 40 foot width. After excavating the area where the building would be placed to level, ICF blocks were placed 12 feet high along the southern wall, stepping down with the slope on the east wall, with the other two walls being “daylight” and utilizing traditional columns embedded in the ground. You can read more about my building here: https://www.hansenpolebuildings.com/2013/06/garage/

 

Loosening Roof Screws

Help! My Roof Screws are Loosening!

Ask The Pole Barn GuruOur office gets all sorts of phone calls. Besides those clients who are potential investors in new post frame buildings, there are those who have made mistakes (or had builders make them on their behalf) and are looking for fixes.

 

 

One call came in earlier this year to Hansen Pole Buildings’ Designer Rachel, who wrote:

“Guy called wondering about buying insulation from us. He was looking for fiberglass. He asked some suggestions and said he has a little issue in his roof.  He has blanket insulation and said his screws are loosening.  I told him I thought it may be the insulation was too thick and the screw was not tight to the framing.  He understands but is wondering what the suggestion may be.  Wondering if he should replace all the screws?  Told him I thought it would still be an issue but not sure.  Thoughts?”

The caller’s building has a product known as metal building insulation under his roof steel. This insulation is most typically a six foot width roll of thin fiberglass insulation usually bonded to a white vinyl vapor barrier. This insulation is installed over the roof framing with the faced side down (fuzzy side up) then the roof steel is applied on top. Installed properly, with the seams tightly sealed (which rarely occurs) and any rips taped, it does make for a fairly effective condensation control.

It also makes for a lousy insulation solution, as the fiberglass is compressed nearly to nothing as it crosses each roof purlin. I’ve heard of builders selling metal building insulation as thick as six inches and trying to convince (and often getting away with it) clients they will achieve an R-19 insulating value!

All of this fluffy insulation wants to cause the roof steel to bend upwards in between the roof purlins, in some instances beginning to look like the Sta-Puff Marshmellow Man. Between this and the compressed fiberglass at each purlin – stress is laced upon each of the roof screws. If the screws are relatively short in length and/or small in diameter, they will eventually work loose (and cause leaks).

Reflective InsulationThe best solution (although time consuming) would be to remove the roof steel and the metal building insulation, replacing it with a reflective radiant barrier and placing the steel back on the roof using larger diameter and longer screws.

If the building owner is willing to accept the look of what he has, he could attempt a fix just by changing out the screws.

The best solution truly would have been prevention – not having used metal building insulation to begin with.

Should a Treated Post Look Treated all the Way Through?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

 

DEAR POLE BARN GURU: I am currently constructing a pole building. I’ve drilled holes through the columns for rebar hairpins to be inserted to tie the columns into the concrete floor. It appears the post isn’t treated all of the way through. What can I do? DRILLING DOUG

DEAR DRILLING: Pressure Preservative Treated lumber does not have to be treated all the way through to be properly treated. As long as the column is tagged as being UC-4B, the column is adequately treated for structural in ground use.

For rebar hairpin holes, after properly marking on every treated post, drill each one using a 5/8” bit. Galvanized re-bar is recommended. If not available, coat rebar penetrating column with an asphalt emulsion, or similar, to isolate re-bar from the pressure treated post. NOTE: #4 re-bar is ½” diameter. Cut re-bars into 5’ long segments and insert one through each column, centering the five foot length in hole. Bend rebar legs, by hand, to a 45 degree angle with skirt boards. Seal rebar, into bored holes, at each column edge with silicone caulking.

DEAR POLE BARN GURU: I read your articles on both reflective heat barriers and vapor barriers.  It seems they conflict somewhat in that for the vapor barrier article you suggest putting the vapor barrier between the purlin and the metal roof, but for a heat barrier you recommend a gap between the roof and heat barrier.  So how do I combine the two?  Would putting a double aluminum sided closed cell barrier like Prodex on the inside of the purlins (creating a substantial gap from the roof) work best?  Thanks in advance for your expertise. TRYING IN TENNESSEE

DEAR TRYING: Thank you very much for reading my articles. As long as the reflective radiant barrier is totally sealed, it should work quite well for both insulation and condensation control.

What House Wrap is Good For

Over the past three decades, house wrap has become a staple feature on millions of buildings. Wrapping a wood framed building in a protective envelope is a good building practice which helps combat a building’s worst enemies: water, moisture and air infiltration. House wrap behind a building’s siding is an excellent secondary defense against the weather.

House wrap is a weatherization membrane which provides a protective layer under a building’s siding and over the wall girts or sheathing. It is literally wrapped around a building, cut out around windows and doors and taped at the seams.

The unique, nonwoven-fiber structure of house wrap resists air infiltration and water intrusion, yet is engineered to readily allow moisture vapor to diffuse through the sheet, helping prevent mold and mildew buildup and wood rot. The fibrous structure is engineered with microscopic pores which readily allow moisture vapor to evaporate but are so small bulk water and air cannot penetrate. Siding, whether vinyl, wood, stucco, brick, or composite, does not completely prevent air and water penetration. House wrap is designed as a secondary defense to help manage a building’s wall systems.

R-Value ratings for insulation are only maintained as long as the air within the insulation stays still and dry. The Department of Energy estimates nearly 40% of a building’s energy loss is the result of air infiltration caused by wind driven pressures from the outside. The opposing forces of pressure between inside and outside walls cause heat and air conditioning to be virtually sucked from a building– through walls, ceilings, sill plates, sheathing joints, top plates, electrical outlets and every inch of the estimated half-mile of cracks in newly constructed buildings. As air infiltrates, it causes changes in temperature which require heaters or air conditioners to work harder. Constant temperature fluctuations also reduce comfort levels. Occupants feel too cold or too warm. Reducing air infiltration increases a building’s comfort factor.

Insulation can help increase the R-value, but it is only marginally effective in reducing air infiltration. When air infiltrates, the R-value itself can be reduced up to 60%. Adding thicker insulation won’t solve the problem. Stopping air from getting in, will.

Properly applied, house wrap helps reduce air infiltration, preserving R-values, conserving energy, reducing heating costs and creating a more comfortable interior.

The tighter the building, the more comfortable and efficient. Unfortunately, the tighter a home, the more susceptible to moisture problems which can cause mold, mildew and rot. So all systems need to be in balance–designed to manage water and moisture effectively.

There are two main ways water and moisture get into wall systems:

Bulk water intrusion from the exterior (rain and snow) can enter the wall and, if not allowed to dry in a reasonable amount of time, can raise the moisture content of the wood above 30% and cause rotting or mold and mildew.

Air transported moisture occurs when air leaks from the warm side of the wall to the cool side. Warm air will hold higher amounts of moisture than cold air. As warm air travels through a wall heading to the cold side, it will begin to cool and be forced to release moisture. This is called the dew point where condensation will occur. When there is a significant temperature drop across the wall, the dew point will occur somewhere within the wall. In the winter months the point of condensation is usually on the inside surface of the exterior sheathing. Moisture carried by air flow through the wall is deposited at the back side of the sheathing and accumulates. In hot and humid climates where air flow is traveling from the outside to the inside, warm moist air from the outside will be cooled on the way to the air conditioned inside, releasing moisture within the wall cavity. House wrap is a breathable membrane with microscopic pores which allow the moisture vapor to dissipate, helping to dry out a wall system to avoid damage.

Moisture Vapor Transmission Rate or perm rate of a material determines the ability for water vapor to diffuse or evaporate through the wall. The higher the perm rate, the more “breathable” the material is and the easier it is for water vapor to pass through. Materials with Perms below 1 are considered vapor retarders since the rate of moisture vapor flow through a 1 Perm material is so low there is essentially no flow. House wraps have Perm rates in the area of at least 58 Perms which is very open to allow moisture vapor to flow through.

What house wrap is not, is a vapor barrier or an insulation. I’ve seen instances where people have applied house wrap directly between roof purlins and roof steel, in an effort to control condensation. House wrap is quite permeable; any warm moist air which would rise to it will pass through to the underside of the roof steel and condense.

House wrap is great…if used for what it was intended for…a secondary defense against the weather.