# another basement insulation question, with a twist?



## Amateuralex (Mar 17, 2012)

So I've read a ton about this in the last few days, including many threads on this site, and I've re-read the buildingsciences document several times. I think that I am up to speed.

However even so I am still asking some familiar questions because I am not sure where my particular scenario lands, and because I am already halfway through framing and I am weighing the pain of the different possibilities.

We're only working on the bottom 4 feet. The rest of the wall is the part above ground level that has the original fiberglass insulation, framing, and drywall. 

I have a 1979 bilevel in southeast michigan. Only about 4 feet are under ground. There's a walkout, and tons of light. Cement slab and cinderblock walls. There are furing strips in the cinderblocks (on the bottom 4 foot section) that they had 1/2" styrofoam insulation in and simple paneling over. The basement doesn't get wet through the walls at all, but during the previous foreclosure the utilities were shut off, the sump pump lost power, and the basement flooded. The bank payed for the floor and bottom half of the drywall to be torn out.

We're finishing it. Our plan was to build nice, fat framing and put standard 3.5 inch fiberglass insulation in and drywall.

We've already built more than half of the framing. I didn't think the insulation would be an issue until I started reading about it haha. The framing is out quite a ways from the wall, and we planned a gap. Our real fear was a power failure and water on the floor. We don't really fear water through the walls or up through the concrete floor.

If it weren't for the furing strips, I could still just put 1" XPS up against the cinderblock and finish with 3.5 fb, which is a reasonable compromise that the buildingsciences guys rate fairly well. We haven't done the top piece of the framing yet so I could insert it in from above. But with the furing strips....I dunno. They say that the XPS has to be airtight with the wall. If I attach it to the furing strips and caulk it, is that going to work? The furing strips are like 1/4 or 1/2 inch.

Any other advice? Sorry for the length, thanks for any input.


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## Windows on Wash (Aug 30, 2011)

Pull the furring strips.

XPS or other foam wants to be tight to the wall and it will be easier to do your air barrier detailing via that way vs leaving the furring strips intact.


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