Quonset Hut Air Sealing
How one man saved $10,000+

In 2017 I decided to build a dedicated workshop to house my tools and my ceramic studio. This was supposed to be a simple inexpensive project, little did I know.

After renting huge excavators and loaders I prepared the  ground for a 30'x50' Quonset Hut (not my favorite style of building but I thought this would be the least expensive solution).

Having tried and failed to erect this with a few neighbors I decided to hire a company that had a crane and 5 guys with experience, even so it took them 8 days to complete the construction ( the weather was not on our side, wind is a no no!).

Be aware this is far from simple as the steel sections really act like spaghetti even using a crane.

Just before the first snow the building was sealed and I started comparing spray foam quotes. The best I received was $17,000 and included an intumescent coating. Way more than the building and foundation cost together and obviously out of the question.

It was then I stumbled upon a company online called Foam Sealants, they had this new spray system that was just what I needed to complete an insulation that would meet or exceed the spray foam R value  for a fraction of the cost. I e-mail William Collins at Foam Sealants who was extremely helpful and answered all my questions no matter how silly. I ended up getting a spray gun and instructions within a few days and started to formulate the process to insulate my workshop.

I purchased 150 sheets 4'x8'x1"  of polyisocyanurate foam from the local HD store and designed a battening system to securely hold these in place. The hut was well put together but in places I could still see small gaps where light was leaking through, even though a rubberized tape was used on every joint. If light was coming through so could air, hence the need for a spray foam system.

Using the gun from Foam Sealants and 12 screw on cans of extreme weather foam I started practicing on small pieces of the Galvalume sheeting left over from the build. There is a knack to using the gun as it sprays at around 80-100lb pressure much higher than I'm used to spraying with automobile paints. After a few trials I was able to lay the foam down in a smooth consistent manner.

I worked out that I had 1100 feet of joints to seal which ended up using the full 12 cans and took me 2 days to complete climbing up and down scaffolding and ladders took most of the time. The result was an air sealed Quonset Hut for just a few hundred dollars and my labour

After completing the spray foam sealing I added the battens and then two layers of polyfoam sheeting. This process took me around ten days over a 6 week period as I was working alone in temperatures that hit 120F at the highest point of the hut. You can see from the pictures how the battens attached and each joint on both layers have been sealed with tape to stop as much air movement as possible.

Already i can see and feel a huge difference in temperature, the outside temps are reading 90F while inside I'm getting 65F at ground level ( 5'-0" off the concrete floor). Each layer of foam sheet is rated at R6.5 so together I'm hoping for around R13. The end walls are covered with HD 2" pink foam which i believe has a rating of around R10

So to summarize the best spray foam quote i received was $17,000 and this method using Foam Sealants products and HD sheets of foam cost $4,800 and i believe it looks much better than the bumpy effect that spraying 2" of foam would produce

 At a later date I am also adding a covering of luan plywood 4'x8'x1/4" to protect the foam from dings , etc.




April, 2018 Initial Correspondence

" I found your site via a Google search and have a few questions. First let me tell you i have a new Quonset Hut that i am about to insulate with 4x8 sheets of  polyisocyanates  foam. But before i do i need to seal the overlapping joints in the steel panels. I like the idea of the 16lb kit and spray gun that you sell but wanted to ask a few questions. #1 what is the minimum temperature to apply your foam. #2 if i do not use the whole 16lb container what happens to the foam in the line from the tank to the gun. I realize the gun can be cleaned but the line ? #3 This sealant will be applied inside the hut but will be subject to possible rain /snow/ sun exposure, how does your foam(white) stand up to this exposure. #4 i will only be applying thin strip of sealant, just enough to cover the joint ( possibly 2" wide strip ) which totals approximately 1000 linear ft will a 16lb can be enough?
Thanks for your time and help" Phil Warren

Joints Before Spraying

Thanks for the great information and offer it is very much appreciated. Attached are a couple of images that may help to explain what I intend to do. The area between the arrows in the close up shot is about 2-3" and thats all I need to coat with foam to stop air movement.

Thanks again

Dr Phil Warren A.I.I.P. C.L.T.

Strappings Before Spraying

"Thanks again William,

I am looking forward to starting this project. The building is large at 50 feet long 16 feet high and 32 feet wide. 

I will take accurate measurements of the surface temperature of the galvalume at the time of application along with relative humidity readings which may be of use to you for future development and marketing. The last few days have been unusually cold and I will take your suggestion and wait until we have a nice sunny day to raise the surface temperature of the building."  

Dr Phil Warren A.I.I.P C.L.T.  

Joints After Spraying

Bill Hi

Did a test today which turned out very well considering I'm not used to the technology. Had a few miss starts with gun pressures and flow, but finally go that dialed in

I will be sending a more detailed report later, when I have completed all the testing, but so far I am very optimistic that this will do the job. I just need to get some practice in using the gun. It does fill in all the gaps even big ones if you hit it at just the right angle. I missed a few spots and will have to go over them again after the foam sets up, I tried to re coat immediately but even with reduced pressure I found it blew off some of the first foam layer. Temperature of the metal was 42F humidity 30% Air pressure to the gun was between 75-100lb and one can of foam covered around 75-80 linear feet of joint. (this will improve as i waste let material)

I have attached a few images from this first test and will take some before and after shots of other areas to illustrate just how much can be filled with this process.

Thanks

Phil

Joints After Spraying