As usual, click any photo to bring up a larger version.
In the spring of 2011 I made a few modest upgrades to my basement shop. I added some insulation and added a few extra outlets, and of course painted everything.
As part of that project I decided to redo the header insulation with spray foam. The header areas had been insulated with fiberglass, without any sort of vapour barrier. I've read many articles over the years of the superiority of spray foam for this sort of application, since it fills and seals every nook and cranny.
Aside: Ryan Shervill has a detailed article on his experience with a Tiger Foam kit in the Sept 2012 issue of Canadian Home Workshop Magazine. I spoke to Ryan at the time of this project and he passed along three pieces of good advice to me.
FIRST: You MUST protect everthing with tarps or sheets of plastic. (Note that there is a Tablesaw under that pile of drop sheets in the middle of this photo.) Since I was doing other work at the same time, I had pretty much emptied the shop as well. A fifty foot roll of thin plastic is cheap insurance.
SECOND: Carry a rag in your second hand. You need that, as every time you release the trigger on the foam spray gun a blob of foam will form at the tip of the gun and fall off. Take a close look at this photo and note all the blobs on the plastic. Since I was spraying into header space, I was releasing the trigger a lot, and every time a blob forms and falls off. I caught a lot on the rag, but also missed plenty, as you can see.
THIRD: You need to cover up. The instructions in the kit also warn you about this. Some kits (not mine) supposedly come with a Tyvek coverall. I wore old clothes, tucked my pants into my socks, wore a respirator, gloves, safety goggles, a baseball cap, and a bandana to cover the back of my neck/head, tucked up under the cap. I will spare you any photos of that... Even with all of that, after my first spraying session I found some foam stuck to my wrist. After that I duct-taped my sleeves to my gloves.
I sprayed in two sessions. According to the instructions, you are only supposed to spray about a two-inch thickness at a time, due to the heat generated (exothermic reaction) as it hardens and dries. I think they are being VERY cautious in the instructions, as I did not really notice the foam being much more than a few degrees warmer than room temperature. It does dry FAST - I was touching the foam with my bare hands within five minutes of spraying and it was solid and dry.
Here are the results of the first session of spraying. Note the wiring that disappears into the foam? Yeah, that. DO make sure that any wiring you want to do is done FIRST. Once that foam hardens, getting in there to do renovation work is going to be a lot harder than when the bay was wide open. Think now about cable TV or computer wiring, or etc... As well, think about plumbing. There isn't usually that much plumbing in a header area, but I took the opportunity to replace one of our outside taps with a frostproof tap before I surrounded the pipes with foam.
About the stink: I was wearing a respirator, so I noticed almost nothing. I had two windows open in the basement, each one with a fan. One was blowing in, one was blowing out. After spraying when I stepped out of the room and took off my respirator I did notice a smell, but really not bad, and it cleared out entirely within 90 minutes. It might have been worse if I was spraying more rooms? Or maybe this kit just uses a "nice" propellant? I'm not complaining!
About coverage: The kit claims 200 board feet of coverage. (A board foot is a volume 12 inches by 12 inches by 1 inch thick.) It was difficult to exactly calculate my area, since these header areas are all broken up, and in some places it was hard to figure out how thick the foam was after spraying. But I did do some figuring, enough that I trust the 200 bdft listed on the package.
About R-Value: The manufacturer claims an R-value of R7 per inch, which is quite good.
In summary... working with a spray foam kit is a messy operation. It also comes with a modest price premium over other forms of insulation. However, it is unmatched in being able to fill irregular spaces and seal everything tight. For a header area like this, I would recommend it.