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DIY tightening up: corner cavities, foundation exposures

A few months ago I had my home insulated with closed cell foam. Now it's time to test it.

A good friend did a blower door test and took thermal photographs. It's a pretty good insulation job. There are places where the foam failed, but not many.

1) the framers created corner cavities "to hang drywall" (haven't they heard of clips?) that the insulators couldn't get to. I want to drill a hole a the top of the void and pump something in there to seal it up. What products can I use?

2) how can I seal the plates and joined parallel studs? The exterior siding is on, but I still have access from inside? Any magic I can do, other than, say, laying sill foam sheets along the face and drywalling over them? Will any kind of caulk that I can apply get drawn into these LONG annoying cracks?

3) concrete foundation exposure. It's built on a hillside with a walkout first floor living area. 12" concrete foundation walls are in the living space which stairstep up, supporting 2x6 framing. I have at least 6", sometimes 8" of foundation in the living space. While the wall faces were framed with 2x4 and foamed, the tops and stairstep sides are just poorly insulated with (maybe) sill foam sheets and then 2x12 plates and 2x6 studs. The thermal images show 72 degrees on the wall face and 42 degrees on the lumber sides and tops. That makes me very sad. I'm losing a lot of heat, and some of the vertical points where stud meets concrete are very air leaky. I'm OK to lose a few inches on the sides and tops of the foundation in the living space for new framing/insulation. I'm looking for ideas. As in (2) above, are there any products that will draw into the spaces where lumber and concrete meet? Should I just tape the cracks and then frame these areas with 2x4, add rockwool or cellulose, and perhaps sill foam sheets for air barrier? Maybe just 2x2? I already did a little vertical section where I could see daylight with 2x4, rigid foam and sealed it with off-the-shelf Great Stuff. Seems to work pretty good, but the thermal camera is gone. :( Any better suggestions?

Thanks so much.

As an aside: I've aired the place out for months, but a good friend cannot walk into the place without beginning to cough violently, and continues to do so for weeks following the visit. I should have gone with cellulose and high-performance wrap and tape, which would have been cheaper and more high performance, but whatever, it's done.

Any hints on improving this job for a DIYer with not much cash?

Judd in the Berkshires

Asked by Judd Maltin
Posted Dec 30, 2012 12:31 PM ET


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