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Basement Interior perimeter walls are 2x2 studs. Need to insulate if opening.

Basement Interior perimeter walls are 2x2 studs. Need to insulate if opening.


Old 05-27-20, 12:17 PM
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Basement Interior perimeter walls are 2x2 studs. Need to insulate if opening.

I am currently working on renovating my already finished basement. The house is built in '79 and it did not have egress windows. I have a contractor coming out this summer to install three egress windows and I am doing the framing inside the basement. Framing to include a another bedroom with egress. I have been doing a bunch of research on how to build and connect these walls properly. I got permits pulled and so far everything was going great. Until I started taking out drywall so I can nail the new wall (perpendicular) to the perimeter wall. I found out the studs are ripped 2x4s down to 2x2 with a 1/2" foam board (not glued) to the wall. In some cases the foam board has already fell down the wall. The permit office for Washington state said I need to insulate according to WSEC if I opened a perimeter wall. I have been reading on this and so far I found it wants R-21 (between the studs) or minimum R-10 (continuous) behind the studs. So I am a bit stuck and I emailed the inspector to see what I need to do so it is up to code on this wall I just opened up. The best I can do with 2x2s is 1.5" foam board (R-7.5). If need be I can tear down all of the perimeter walls and rebuild. Thoughts?
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Old 05-27-20, 05:08 PM
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Lots of basements have been finished in all sorts of crazy ways. I'm glad they are coming up with a standard.

Tear down the existing and use 2" foam board (R-10) build a 2x4 wall and leave it empty or fill it with R-11 or R-13 if you feel like it. Then run electrical in the walls. If you have electrical in your 2x2 walls it's probably not up to code either.

How much of the exterior walls you do is kind of up to you/them. Seems kind of dumb to just do a section.
joecaption voted this post useful.
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