Hello:

I’m insulating my garage with leftovers from another project. Main reason is to help the room over the garage be more comfortable as it’s currently surrounded on 5 of the 6 sides with unconditioned space. Figure insulating the garage will slightly expand the thermal envelope of the house. Also, if I throw a space heater in there in the winter, it’ll actually be mildly useful as a workshop if needed. Heck, pulling the van in after a ride and shutting it off will warm it up.

It has 2×6 walls 24OC. I started with leftover rockwool for part of the north wall, then switched to fiberglass – these are unfaced. I’m working my way south with glass along the east wall. The west wall of the garage is the house. The south wall has the garage door (one car) and only about 5′ of total wall area outside the door.
 
I’d planned to use some 3.5″ Thermax panels that’re also left over for what the fiberglass does not cover, but then remembered that the Thermax has foil on both sides to provide moisture “barrier”. So, wondering if having these in stud bays up against the OSB sheathing in the garage is a good idea. Since the garage is unconditioned 99% of the time, I’m thinking the delta T between the garage and the outside will be low, so condensation risk is low. BUT, would hate to have a mold/rot problem in one section because I used Thermax and shouldn’t have.   Maybe it’d be better to use the Thermax, but only while leaving a gap between the Thermax and the OSB.

Thanks all!

Wayne “too much to think about” Maceyka

P.S. Part of the driver to do this is to use the leftover bits. The waste associated with my projects drives my bananas.