Tag Archives: open cell spray foam insulation

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.

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.

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.