Tag Archives: spray foam

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

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

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

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

 

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

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

 

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

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

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

 

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

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

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

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

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

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

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

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

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

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

 

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

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

 

 

 

 

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

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

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

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

 

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

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

 

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

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

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

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

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

 

 

 

 

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

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

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

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

 

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

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

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

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

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

 

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

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

 

Flash and Batt Insulating Barndominium Walls

Flash-and-Batt Insulating Barndominium Walls

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

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

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

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

 

Figure 27-5

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

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

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

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

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

 

A Post Frame Addition, California Muster, and Ventilation

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

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

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

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

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

 

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

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

Thanks, DAN in LOS ANGELES

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

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

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

 

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

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

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

 

Minimizing Post Frame Ice Dams

Minimizing post frame ice dams

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

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

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

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

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

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

How do we solve ice dam problems?

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

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

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

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

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

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

Crawlspace Skirting, Adding Spray Foam, and Rafters

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

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

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

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

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

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

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

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

 

Building Height, Building on Existing Foundation, and Spray Foam

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

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

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


 

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

 

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

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

 

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

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

 

 

 

 

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

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

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

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

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

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

 

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

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

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

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

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

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

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

 

 

 

Spray Foam Insulation: What’s the Stink?

What’s the Stink?

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

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

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

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

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

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

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

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

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

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