Daox,
Thought you'd appreciate my caulking/insulation project, it's been going on for about 15 years now...
Here's a shot of a corner of the kitchen showing the fully layered roof, a section of partially completed wall and a section of fully completed wall.
I have put three layers, each of 2-inch thick rigid foam insulation into the entire roof of my house. I cut the foam to fit as closely as I could, which usually meant that I needed to use a piece of plywood and a heavy hammer to pound them into place. Since my house is 117 years old, nothing is square and straight, so any big gaps I filled with expanding foam. Any small gaps I filled with a caulk gun. I did this at every layer, so the infiltration should be quite low.
Here's a shot of an adjoining wall showing three stages of the layering process.
The house had the old style rough-cut 2x4, when they were actually 2 inches by 4 inches. I built up the 2x4 so they were finally 2x6. Then I put the foam in.
As you can see, I will need to build up the window opening.
When I started this project, I had never heard of
"thermal bridging", which refers to the fact that heat loss can occur through the 2x4 (or 2x6 in my case), lowering the R-value of your insulated wall by 15%. On the walls left to do, I'll work out some way to stagger the 2-inch build-out so that there's a break in the thermal bridge.
I'm figuring the R-value of the foam to be R-4.5 per inch, so a 6-inch ceiling/wall is R-27. When I started this project, R-27 roofs were over code, and R-27 walls were considered to be insanely extravagant. Now, code for new construction is R-40 in the roof and R-21 in the walls. If I add 2 inches of isocyanate foam to the roof, I'll be at code.
I've been using Expanded Poly Styrene (AKA: EPS) because it is closed cell and non-hydroscopic, and is cheaper. So R-4.5 per inch, will be R-4.5 20 years from now.. Isocyanate foam is hydroscopic and will gradually absorb so moisture and will gradually reduce in R-value.
The price of insulating board has risen substantially since I started this project, but the cost of heating fuel has risen much faster.
Best Regards,
-AC_Hacker
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%