Combination fiberglass batts/foam panels in old home.. [Archive] - Home Construction Forums

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rich121
08-23-2009, 10:52 PM
I have a 1930's 2 story, 2x4 stick frame house.
I have completely gutted the 1st floor rooms and I'm doing a complete remodel, rewire, and replumbing of the house.
It has an upstairs that has rooms and a bathroom, but no attic space, as the rooms are incorporated with the rooflines.
I don't have enough depth in the 2x4 walls or the 2x6 ceiling space for enough fiberglass insulation. I live in Eastern Washington State where it gets 100+ degrees in the Summer, and below zero in the Winter.
I need at least R-21 in the walls, and R-38 in the ceiling.
My plan is to "fir-out" the walls with 2"x3" lumber to make them 6" deep. I would like to use R-13 (3.5" deep) fiberglass in the outside (original) wall space, and use "R-Max, Thermasheild 3" (closed cell, polyisocyanurate foam bonded to reinforced aluminum foil facers on each side)on the most inner part of the wall, where the added 2x3 strips are.
I am only mixing because of the high cost of the foam panels.
For the ceiling, I would like to use (2) 2" and (1) 1" layer of the foam panel (R-6.5 per inch) this would give me a combined R-value of R-32.5.

I believe that using this foam board, I would also be sealing the house up much better than just using the fiberglass insulation.

I would like suggestions and thoughts from anyone experienced with this type of insulation, and what/how I should keep or change what I'm doing?

rich121
08-25-2009, 11:16 PM
Anybody out there?

Don_P
08-26-2009, 02:59 AM
I did this to the ceiling/roof of my house using R19 faced batts in the rafter bays and blueboard foam interior of that. It has worked well for us. You might want to look on the buildingscience.com website for more info.