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How much more sealed will a house become with sheetrock?

tundracycle | Posted in General Questions on

If we want to hit say 1.0 ACH50 when complete, how close do we need to get when testing with just insulation (closed cell spray foam)?

Our first test was 3.42. After some work our insulation contractor has us down to 2.1 ┬áHe says that 1.7 will be close enough and that with Sheetrock, paint and other stuff we should hit 1.0. That seems like too much to me. I’d think we’d want to be about 1.1 or 1.2?


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  1. CramerSilkworth | | #1

    Depends, but if the ccspf is your main air barrier, I wouldn't expect more than another 0.2 ach50, maybe 0.3, with the rock. If it's more than that, there's something you should be able to catch now and fix properly. Are you looking for leaks while the blower door is running?

    Only things deliberately connected (fully sealed) to the air barrier really add any air tightness. Air barriers are systems of multiple fully connected components - just adding more layers of things does not an air barrier make (unlike, say, flashing and drainage planes where redundancy counts).

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