A question about insulation of a basement.
First, the house is built near Montreal, Québec, Canada.
Climate, cold in winter and hot and humid in summer.
To give an idea, -30 C to the coldest in winter, and + 30 C maximum in summer.
The wall of my basement is constructed as follows:
-
The concrete wall is underground for 2/3 (2/3 of the bottom … of
course!). A membrane was installed on the outside and a drain
installed to correct water infiltration. -
Inside, a 1.5 inch air space was left between the concrete wall and the
wooden wall. -
The interior wall of 3 1/2 inches is made of wood insulated with rock
wool (Roxul). -
A plastic air barrier was sealed on the wall, so inside.
I suspect that the air space is harmful: possible convection and condensation.
Can you find me serious links, supported by science explaining why this is bad, if that is? What is the risk of this construction?
Now what can I do, do I have to do with this wall?
(sorry for my english… google translate help me a little bit!)
Best Answer
I'm in a similar climate, and what you describe is standard aside from the insulation. Rock wool is no longer used in favor of fiberglass or spray foam where I am. I have no reason to think that it's a problem, though.
Convection isn't a concern outside the heat envelope. Condensation isn't either because it's on the cold side.
That said, some recommend against vapor barriers in basements due to the dual-membrane situation they create in conjunction with the foundation waterproofing. This can trap moisture and promote mold and decay. It was probably installed as temporary covering for the insulation.