Double-stud wall insulation methods
We are building a new house in Wisconsin, zone 6, and are planning on using double wall construction, originally with dense-pack cellulose. None of the local insulators that we have talked to will install the cellulose.
I am still searching for another insulator, but in the meanwhile I have been considering a flash and batt method with 3 to 4 inches of spray polyurethane closed cell foam on the exterior side of the wall and either batt insulation or blown-in fiberglass making up the remaining cavity.
The space between the walls is 5 inches. Looking at a product like Roxul, can it be fitted where the SPCCF has been applied? It seems like that would be very fussy work. Also, the 5 inch space presents a challenge. I like the density of the Roxul, but I think this might not be the right application.
Part of the appeal is that we could do the batt insulation ourselves and are motivated to fit the insulation to the cavity. There will be no openings in the exterior walls except for windows and doors. (Electrical outlets will be in the floor.) Interior walls are 5/8" drywall. Stud spacing is 24" OC.
If we skipped the flash part and just used the Roxul, what type of vapor barrier should we use and where should it be placed? Exterior sheathing is OSB with Tyvek and cladding is cement board horizontal siding above and full stone veneer below. Rain screen is planned.
Insulation bids have been over $10K and that is for a 900 SF house and garage. That includes 2 inch flash foam of ceiling and 4 inch flash foam of exterior walls.
Does the double wall construction commit us to using a spray/blown-in method of insulation?
Posted Jun 29, 2012 7:10 AM ET
Edited Jun 29, 2012 7:55 AM ET
Other Questions in Energy efficiency and durability