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Sealing RIM Joists

Dabbi | Posted in General Questions on

Attached is an energy audit done for my Single Family home. I have a cold home and I am getting things in the report fixed.  This question is about the basement air leaks from the Rim Joist (Pages 6 and 7 of the report). Since then, my basement has been mostly finished (the walls are up), so I have no easy access to Rim Joists. The basement is cold and the thermal imaging shows air leaks along the Rim Joists. I can also feel cold air coming out of the outlets and switches (the switch plates are not installed yet).

1. Is it worth cutting a foot of ceiling drywall and sealing the rim joists? I am getting estimates like $6000.
2. What is the easiest way to get access to the rim joists? Any guidance would be helpful.


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  1. mgensler | | #1

    We did this and our basement is now the most comfortable room in the house. Maybe you can reduce the cost a little by having the spray foam guys hit the top plates and other penetrations in the attic while they are there. Those 2 part diy spray foam kits are also perfect for this type of air sealing.

  2. Dabbi | | #2

    @mgensler - If I understood you right, you suggest that it is worth the expense of ripping out the drywall, exposing the rim joist and insulating the rim joist. Right?

    If so, should I just spray foam the rim joist between the floor joists. How many inches? Does 2 inches sound good or should I seal with spray foam, put foam board and the batte?

    Thanks in advance

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