Stove room wall insulation

I especially liked when the saw would bind and the sheet would jump so the blade would tear into the piece I just cut. Fun times in the middle of summer getting covered with hot molten foam sticking to your arm hair and all over your clothes.

Another possibility would be the bubble wrap insulation stuff (Refletix at Lowes) Seal it to the outside wall, make a loop and staple to the inside edge of the the 2x 4 wall and it is a huge r value and vapor barrier (look at the website for the install possibilities). I did 2 crawl spaces with R 19 in the floor joist cavity, then stapled the Refletix to the bottom of the 2 x 6's and that helped my 2 rooms tremendously. Plus I felt like a baked potato when I was in a 18" crawl space on my back staring at aluminum everywhere.

 

I'd love to put some insulation under the floors where we have a crawl, but most of it is inaccessable without some major work....as in, I ain't doin' it.

 

I've got that Reflectix covering the rigid foam insulation on my foundation walls. I put it up more for prolonging any outgassing from the foam (in the event of fire), than for insulation value - but I'm sure it helps too. Know what you mean about the baked potato feel.

 

Late to the party and didn't read every post, but how about some fan-fold silicone'd in with batts on top of it. Wrap the fan-fold all the way around the cavity. Get the wind barrier benefit of foam and superior insulation of batts. Just thinking out loud. Heck, you could even do the reverse and put the batts in then fanfold over the top of the studs and screw the drywall over it.

 

Does the fan-fold have some vapor barrier on it?

 

It's usually closed cell foam...so water and air tight. Used a lot under vinyl siding and on the outside of foundations/basements.

 

What sort of batts are you using? I've never seen any that can match foam in terms of R value.

 

XPS is about R5 per inch...so yes, it is more insulative if you fill the entire wall cavity with foam vs a fiberglass batt at R-13. I'm not sure if Dave was talking about a full 3.5" of foam...I assumed not and maybe I shouldn't have.

Foam ain't cheap either...about $85 for a 4'x8'x3.5" sheet.

 

I've ran plenty of pink foam thru my table saw, i have a table behind the saw to support long rips and added a support out front so the sheets don't sag when starting the cut. If it flops around at all you'll bind the blade and risk a kick back.
I've done a fair amount of foam in the basement, i was filling cavities in steelstuds, 2-1/2", i started with 2" and 1/2" sheets, using a utility knife and snaping the score line, the edge of 2" isn't as square as the saw cut which i didn't care for, it left a gap which defeats the point of the project in my opinion, yea, i have issue's. In my area 1" is about 1/2 the price of 2" and being it's more flexable it's worth the extra cuts. I'd do the entire cavity in foam and seriously consider adding another full layer before sheetrocking the wall to the reduce the thermal bridging of the studs. I did this on a ceiling and the only drawback so far was when putting up the drywall was it would suck in as more screws were added and i had to go back and tight the first screws that were put up. There was also dense pack behind this so that was probably what was compressing, it's been a few years since and the ceiling looks great, nothings poped, yet.

 

The kicker is I don't need much. There's exactly 4 stud bays that aren't even a full 14.5" wide, and most of the rest is 3 small cavities above and below each of the 4x5' windows.
Might need 2 sheets. I know, still more than a couple rolls of batts.
I could do a 2" layer, then a 1.5" on top of that with great stuff all around.
Also considering the Comfort Batts.
Still don't have the windows and doors, so...........