It seemed that the best way to insulate the rear wall of the utility room would be spray on insulation. Most of the wall is below grade so I knew it was insulated on the exterior but the top 11” is at least partly above grade. This area is closed in with plywood and it was leaking a lot of cold air when I had the blower door test done.
Leaking air was especially bad around the pipes that went through the ceiling. I wanted to fill these holes and also cover the styrofoam above the concrete side walls and the plywood behind the pipes and boiler on the back wall with a layer of spray on insulation.
As an experiment I bought two kinds of two component spray foam canisters. this type of foam is better than single component cans for sealing large gaps and has a higher R value. Both of the brands I ordered are rated as low GWP (global warming potential) with no harmful CFCs (chloroflourocarbons). The Dap Touch and Seal brand was a little less expensive and claimed a sprayed volune of 15 board ft the other was Froth-Pak, at 12 board ft. Both are high expanding low pressure closed cell foam with about a 6 R value and are fire resistant. It took a few months before I got around to this project. I ordered the foam in January. Cleaning up from the disconnected dryer vent was the first unanticipated step to spraying the upper sides and back of the utility room.
Unfortunately the Dap brand canisters were held together by delicate plastic straps that split from the triggers when I accidentally dropped them. Holding the plastic connection up was supposed to hold both triggers in an open position, instead when the plastic broke off the triggers didn’t work. I even had Dave try to squeeze the triggers for me but the mixture went as far as the nozzle and no further. How disappointing.
The next day I unpacked the Froth-Pak box. The whole system was better quality and better thought out. The bottles screwed into a dual cap piece and had a shoulder harness. They were designed to empty upside down. There were three nozzles in hard clear plastic instead of two soft plastic nozzles. The directions were clearer calling for the bottles to be well shaken. The handle was the only spray controller unlike Dap that required both the triggers on the bottles and the hand sprayer. I was elated when the mixture actually sprayed out of the nozzle.
Spreading it evenly was another matter.
The more I tried to fill the holes the more foam dripped down away from the hole. I ended up with quite a clumpy mess. And the bottles emptied way before I got the wall sprayed.
Since I had a lot left to seal I went to work on the Dap kit after learning from the Froth Pak.
I taped the bottles together so they resembled the Froth Pak set-up. Then I taped a small piece of 2×2 between the triggers. I had to notch the edges so the triggers would not rotate away. I cleaned the foam from the soft plastic nozzles to reuse them. Then I shook the bottles and held them upside down and squeezed the triggers together while holding the spray gun handle down. The foam left the nozzle!
This foam seemed more liquid than the Froth-Pak but I was able to fill the gap at the top of the plywood.
I pushed the foam as far into the corners as I could. As I filled the upper holes the foam seemed liquidy and wanted to drip even more than the Froth-Pak.
When the Dap foam no longer sprayed out it seemed the bottles still held some liquid but I think one side ran out before the other. I could not tell that there were 3 more board ft in the Dap bottles although they were taller. I was just glad I was able to use most of it and did not have a total loss of $50.
The upper corner still felt cold so I added some leftover rock wool to the space. I will have to open a new package to fill the other side. But I hope I sealed it enough to help with the blower door results.
The foam is too difficult to control to spray behind the pipes on the rear wall. I ordered more Froth-Pak but plan to use it in the crawlspace.