What exterior foam insulation on retrofit?
My dilemma in my retrofit is this: many years ago, before I was better informed as to where the vapor forms in my exterior walls in my home in Maine, I installed 1 inch of ISO over my dense-packed cellulose walls. I have now been educated to the dramatic thermal inefficiencies in walls stemming from bridging.
I am planning on retrofitting the exterior. I keep coming back to the same prescription: never use two vapor retarders on opposite sides of the walls. The one-inch iso is .03 I believe, and I have been eyeing 2-inch XPS on the exterior, giving an R-10 bump with a perm of .55.
I have also read that there can be an applicable rule of, five times more perm on the exterior than the interior. Will this hold true for a home in Maine?
Posted Thu, 02/14/2013 - 16:27
Edited Fri, 02/15/2013 - 08:05
Other Questions in Energy efficiency and durability
Best practices ideas for retrofitting existing PWF built in muskeg and best practices for foundations for new builds in muskeg (i.e. very wet !) and a severe cold climate