Replies

1. GBA Editor
   Martin Holladay | Dec 31, 2011 05:35am | #1

   Jason,
   First of all, make sure that the sheathing is dry before you insulate.

   Rigid foam makes more sense than fiberglass batts in this case. Be sure to install the rigid foam -- at least 2 inches, but the entire stud cavity if you have the patience -- in an airtight manner, by sealing the perimeter of each piece of rigid foam with caulk, canned spray foam, or high quality tape.

2. 
   schatzyman | Dec 31, 2011 08:10am | #2

   Thanks Martin -

   Generally, in remodeling (when it isn't practical to put foam on the outside of the sheathing) in this climate - is rigid (air tight) or spray foam the best general practice for wall cavities?

   It seems to me that providing this air sealing at the sheathing with foam is easier & more effective then batts with poly vapor on the inside.

   I'm assuming if I only used 2" above I could safely fill the rest with un-faced fiberglass?

3. 
   davidmeiland | Dec 31, 2011 10:48am | #3

   In 4a I don't think you want or need the poly.

4. GBA Editor
   Martin Holladay | Jan 01, 2012 06:06am | #4

   Jason,
   Spray foam is easier to install (especially around wiring) and is more likely to provide an airtight installation. The reason I didn't mention it in my first answer is that your wrote, "Spray foam for this wall isn't an option."

   You are correct that either spray foam or air-sealed rigid foam will perform better than fiberglass batts.

   And David is right that you shouldn't include interior polyethylene in your climate zone.

   Good luck.