# XPS for rim joist



## joecaption (Nov 30, 2011)

Tight to the rim, you do not want any air space.


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## Windows on Wash (Aug 30, 2011)

joecaption said:


> Tight to the rim, you do not want any air space.



:thumbup:

That right there.


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## Mikenra (Jan 8, 2012)

That's unfortunately what I thought. With the cavity being used as a wire chase, not possible. Don't think foam is a viable option since I'd have to de rate the wires encased in it. Any thoughts?


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## Windows on Wash (Aug 30, 2011)

As long as it is airtight, the offset is not that bad.

Cut the foam tight to the framing and seal with foam or sealant. You will still be stopping the air loss/gain which is the bigger issue when it comes to energy loss.

If you want, stuff some rockwool in there before you put the foam back and seal it.


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## jklingel (Dec 21, 2008)

Or, poke a hole or two in the foam board and squirt in GreatStuff or the like; good luck re-wiring in the future, though.


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## Windows on Wash (Aug 30, 2011)

jklingel said:


> Or, poke a hole or two in the foam board and squirt in GreatStuff or the like; good luck re-wiring in the future, though.



:laughing:


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## jklingel (Dec 21, 2008)

Yeah, some folks are just looking for the quick and dirty answer, so I thought I'd throw that one out. If the house is almost expired anyway, it may be applicable. I'd hate him/her forever if I ever had to re-wire in there, though.


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## Mikenra (Jan 8, 2012)

jklingel said:


> Yeah, some folks are just looking for the quick and dirty answer, so I thought I'd throw that one out. If the house is almost expired anyway, it may be applicable. I'd hate him/her forever if I ever had to re-wire in there, though.


Nope just looking for the right answer. Think I got it. Thanks all!


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