Insulation, Radiant and Vapor Barriers - How to seal behind basement rim joists?
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wgc
06-12-09, 08:47 PM
I know I need to insulate and seal around my my basement rim joists but I'm a little stuck on how to handle the ones parallel to the joists.
The basement wall is a double wall of blocks, with the outer wall continuing up to form the wall of the house. The basement rim joists parallel to the joists are an inch or two above the inner wall and a half inch inside the outer wall. How can i seal that?
I don't like the idea of just sealing the gap below the rim joist since that would trap moisture behind the joist. How about filling the cavity behind the joist with expanding foam?
Assuming that's a better idea, the next questions are how and what?
- how many spray cans of foam it would take to fill that half inch gap behind a ten inch joist the width of the house (30'?)? How can I figure out their coverage?
- The straw on those cans of spray foam are probably 8" long and straight. Any idea how to extend them? I don't have straight-on access to the area behond the rim joist, so I need a straw that goes out a few inches, takes a right angle, then goes up 10".
The basement wall is a double wall of blocks, with the outer wall continuing up to form the wall of the house. The basement rim joists parallel to the joists are an inch or two above the inner wall and a half inch inside the outer wall. How can i seal that?
I don't like the idea of just sealing the gap below the rim joist since that would trap moisture behind the joist. How about filling the cavity behind the joist with expanding foam?
Assuming that's a better idea, the next questions are how and what?
- how many spray cans of foam it would take to fill that half inch gap behind a ten inch joist the width of the house (30'?)? How can I figure out their coverage?
- The straw on those cans of spray foam are probably 8" long and straight. Any idea how to extend them? I don't have straight-on access to the area behond the rim joist, so I need a straw that goes out a few inches, takes a right angle, then goes up 10".