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Vapor Barriers, Post Longevity, and Spray Foam

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

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

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

 

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

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

 

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

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

This entry was posted in Roofing Materials, Pole Barn Planning, Barndominium, Ventilation, Building Interior, Lumber, Columns, Insulation, Pole Barn Homes, Pole Barn Questions, Pole Barn Design and tagged , , , , , , , on by .

Lack of Adequate Attic Ventilation

Lack of Adequate Attic Ventilation is Sadly Becoming a Recurrent Theme

If only providers of poorly designed pole barns could be keel hauled…..

Reader AARON in CASPER writes:

“Hi there, I have a 40×104 pole barn. It has 16 foot sidewalls with rafters every 4 foot on center for snow load. The entire interior of the building is spray foamed to about 1 inch thickness. I want to install a ceiling under the rafters and put in r 38 insulation on top. I know that there were ridge vents when the building was put together, however the guy who spray foamed sprayed over the vents. I plan to clean that out. My question is are just those ridge vents enough for ventilation or do I need additional intake vents. The building does not have an overhang or soffits so they would not be easy to install. Do you have any suggestions?”

Mike the Pole Barn Guru says:

You certainly have a challenge at hand.

Here are requirements for adequate ventilation: https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/

You could add 1000 square inches of NFVA (Net Free Ventilating Area) vents in each gable end and it would meet Code (along with cleaning out your ridge vents for an exhaust), however this would prove to be a very poor design solution as your attic air flow will be highly constricted once you get past first truss in from each end.

Short of a major rework to add enclosed ventilated soffits, your best design solution if going to be to have a conditioned attic – besides, one inch of closed cell spray foam is not adequate to control condensation (it usually takes no less than two inches).

To get to R-38, you could increase closed cell spray foam to a total of 5-1/2″ or add another inch of closed cell plus 6-1/2″ of open cell.

Before considering adding a ceiling, confirm your roof trusses are adequate to carry extra weight. They need to have a minimum BCDL (Bottom Chord Dead Load) of 5 psf to support ceiling joists 24 inches on center and 5/8” sheetrock.

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

At What Temperature Can You Not Spray Foam Insulation?

At What Temperature Can You Not Spray Foam Insulation?

Reader DON in ELLSWIRTH asked this question.

Mike the Pole Barn Guru responds:
Ideally, spray foam insulation should be installed during warmer months. Once temperatures start dipping, spray foam insulation installation processes become a lot more challenging. For a successful spray foam insulation installation, application side surface typically needs to fall between 60 and 80 degrees Fahrenheit. If temperatures are below this range, there’s a greater potential for equipment breakdowns and a larger chance foam will pop, shrink, and fail to adhere properly to substrates.

With this said, it is possible to successfully install spray foam insulation when temperatures dip below this range.

Installing spray foam during winter months is more challenging, but one can increase potential for a successful installation in several ways. One way to successfully apply spray foam insulation in winter, despite less than ideal conditions, is to use a winter blend of spray foam. Closed-cell spray foams can be formulated into a winter blend allowing them to withstand colder environmental and surface temperatures. If you want to install open-cell spray foam insulation, however, it’s not possible to create a winterized formulation. Instead, you must create a suitable environment at installation site (e.g. add heat to building).

In addition to using a right blend of spray foam, making application adjustments for lower ambient temperature is also important. When applying spray foam when temperatures are colder, it’s important to keep hose off any ice, snow, or concrete, as doing so will cause heat to be drawn out more quickly. Minimizing distances between spray rig and application site will also reduce heat loss by reducing hose amount exposed to elements.

On especially cold days, using a smaller application gun mix chamber can keep material warmer. Doing so will slow material’s flow so it stays in heated system longer. It’s important to note installation process of spray foam is generally much longer during winter due to need for such accommodations.

Installing spray foam insulation is a complicated and potentially dangerous process if you don’t have necessary equipment and expertise. As such, it’s always best to hire a professional spray foam insulation contractor—especially during winter, when installation processes are even more complex.

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

More Thoughts on Polyurethane Foam

More Thoughts on High Density Polyurethane Foam for Column Backfill

Reader STEPHEN contributes a question regarding high density polyurethane foam for column backfill:

“Hello, I have this question I would like to pass along to the “pole barn Guru” to be answered, I doubt I will get the answer I need in the time frame, but I think its going to come up more often, so  I am guessing now is a good time to ask.

With the idea of burying a 6x6x14 into concrete, the risk of Rot is very high. At a cost of about 50$ per post,  you want to protect your investment,  so many people are using a 6x6x10 and using the Study-wall brackets, but that drives up the cost to about 80$

So my question is, has anyone looked into using the new polyurethane instead of concrete?

https://www.homedepot.com/p/Secure-Set-1-Gal-Concrete-Alternative-High-Density-Polyurethane-Post-Setting-Foam-White-5-Post-Kit-SS-4-10/206497548”

Stephen ~

Hopefully this response will prove to be timely in regards to your project.

Mike the Pole Barn Guru responds:

Let us begin with a discussing to overcome a fear of a “risk of rot is very high”. Actual field studies have proven an ability of properly pressure treated lumber to withstand decaying forces for greater than human lifespans: https://www.hansenpolebuildings.com/2017/12/will-poles-rot-off/. Trick, of course, is finding properly pressure preservative treated timbers. Five years ago I penned this article for a post frame industry magazine: https://www.hansenpolebuildings.com/2014/05/building-code-3/. Little has changed since then – lumber dealers and big box stores continue to sell pressure treated timbers without advising consumers as to what those timbers can actually be used for.

Now let’s discuss using high density polyurethane foam for setting columns, rather than concrete. At this year’s National Frame Building Association Expo there were several vendors promoting using their high density foam for setting posts – all of them having experience only from setting of utility poles. Utility poles carry a minimal downward load, so their holes are barely larger than column diameters, making calling for a pre-mix concrete truck impractical. Lateral loads on utility poles are also minimal as compared to columns in a post frame building, so a little high density foam easily provides a solution (and sets up quickly – allowing crews to move expediently from pole to pole).

Here is some more reading on this subject: https://www.hansenpolebuildings.com/2014/02/high-density-foam/.

Besides not being Code conforming, there is an issue of cost. Your suggested product provided at The Home Depot will provide a volume equal to five 80 pound bags of concrete (or 1/10th of a yard) for $37.63 or $376.30 per yard. With pre-mix concrete prices being roughly $100 a yard, concrete being Code conforming and not contributing to decay any more than would high density foam, it seems to me to be a no brainer.

This entry was posted in Pole Barn holes, Pole Barn Questions, Building Department, Pole Barn Planning, Pole Barn Structure, Concrete, Budget, Columns and tagged , , , on by .

Considering the Differences Between Closed and Open Cell Spray foam

Originally published by: Fine Homebuilding — May 21, 2016 by Mr. Rob Yagid, a former editor at Fine Homebuilding. Excerpted from Mr. Rob Yagid’s article with contributions from ABTG Staff.

The following article was produced and published by the source linked to above, who is solely responsible for its content. The Pole Barn Guru™ 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, The Pole Barn Guru™ cannot vouch for the validity of any facts, claims or opinions made in the article.

In an article by Rob Yagid for Fine Homebuilding, which was sponsored by Versi-Foam Systems, the question addressed is what is open cell versus closed cell foam? Rob delves into the debate about the properties of open-cell versus closed cell with the following points:

Much of the information you’ll find about spray foam is dedicated to its R-value and its permeability.

These traits have an overarching impact on the performance of open-cell and closed-cell foams. In most closed-cell foams, an HFC blowing agent is captured in the foam’s cell structure. This gas has a better thermal performance than the air-filled open-cell foam and gives it a higher overall R-value.However, while HFC-blown closed-cell foam might initially have an R-value as high as R-8 per in., as the blowing agent evaporates through the cell walls and is replaced by air, its R-value diminishes.

Closed-cell foam’s “aged” R-value is roughly R-6 per inch. Some manufacturers produce water-blown closed-cell foams. These foams have the same performance properties as HFC-blown foam, but slightly lower R-values at around R-5.5 per in.

Closed-cell foam’s greater density, 2 lb. per cu. ft. compared with open cell’s 1⁄2 lb. per cu. ft., also increases its R-value and offers it the rigidity that open cell foam lacks.

Structural testing, by a variety of spray foam manufacturers has confirmed that closed-cell foam increases the lateral shear and wind pressure strength of conventionally framed walls. Closed cell foam also has a low vapor permeability rating (roughly 0.5 perms at a thickness of 3 in.) and is considered a class-II vapor retarder, meaning that it’s semi impermeable.

Open-cell foam has a greater expansion rate than closed-cell foam. It expands 100 times its initial volume (closed-cell foam expands only 30 times its initial volume), so less of the foam is needed to insulate a house.

Although both foams will dry if they ever get wet, open-cell foam is vapor permeable and dries much faster than closed-cell foam.

Open cell’s one major weakness is its lower R-value, roughly R-3.5 per in. This means that when used in a 2×4 exterior wall, it will create an assembly that’s approximately only R-12, which won’t meet code in most parts of the country.

Spray polyurethane-foam manufacturers can rely upon several facts when it comes to marketing their products. According to the U.S. Department of Energy, up to 30% of a home’s heating and cooling costs are attributed to air leakage. Spray polyurethane foam is an effective air barrier and significantly reduces energy loss. Combined with a higher thermal resistance (R-value) than most other forms of insulation, it’s no wonder spray foam is often relied on to help make houses ultra-efficient. The key to proper use is knowing your climate, construction practice, wall and roof assembly types and building code requirements with a particular focus on continuous insulation. For more resources on the value of spray foam, visit continuousinsulation.org.

This entry was posted in Insulation, Building Department, Pole Barn Planning, Pole Barn Structure, Building Interior, Pole Barn Homes and tagged , , , , , on by .

Spray Foam Insulation, Steel Roofing and Corrosion

Hansen Pole Buildings’ Designer Rachel recently had an interesting discussion with a client. The gist of the discussion was the client had heard spray foam insulation will corrode the steel and void the warranty of the steel.

Rachel did some research and found this article: https://www.greenhomeguide.com/askapro/question/can-i-apply-spray-foam-insulation-directly-to-the-underside-of-a-metal-roof.

When I added the external elevator shaft to the rear of our steel covered post frame home, my choice of insulation was closed cell spray foam. Although I knew it was going to be more expensive than other choices of insulation, I was (and remain) convinced of it being a superior R-value, as well as completely sealing the system. In the case of our addition, the steel roofing was applied directly over the wood roof purlins, without any solid sheathing or other barrier.

So, will spray foam insulation actually corrode the steel?

Highly unlikely, as from the research I have been doing there appear to be no chemicals in the spray foam which would react with the steel or the galvanized or galvalume protective layer over the bare material. Most steel roofing is factory finish painted, which adds yet another barrier surface in the interior primer paint coat which further isolates the steel from the spray foam.

There are some cases where I could see some challenges.

One would be if someone went on the cheap and used open cell spray foam, rather than closed cell. In this case moisture could get through the open cells and be in contact with the underside of the roof steel.

The other could occur if there was a leak in the roofing or the ridge cap which would allow moisture to get trapped between the roof steel and closed cell foam.

As to the warranty discussions – steel warranties primarily cover fade and chalking of the exterior finish of the steel. Personally I am hard pressed to see how it is the application of closed cell spray foam insulation on the interior of the steel roofing, would influence the life of coatings on the exterior.

Of course everyone looks for an “out” when it comes to warranties, and the reality is a good warranty protects the seller/manufacturer far more than it protects the consumer.

If I had it to do all over again, I would still closed cell spray foam my own steel roofed building. Check back with me in another thirty or forty years and see if my opinion is yet the same.

This entry was posted in Insulation, Pole Barn Questions, Roofing Materials, Steel Roofing & Siding and tagged , , , , on by .
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