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Cover closed-cell spray foam with draped insulation for unfinished basement walls?

Shaggy Rogers | Posted in General Questions on

(Zone 5) We specified R-20 min CCSF on interior of all foundation walls with the assumption that it would mean framing a wall, spraying, and covering with drywall. This will be done for all finished areas, but not the unfinished areas. My general has stated he did not bid the job this way, and there will be an upcharge for framing and drywall. Is the approach he has stated even allowed? What issues would there be? He is planning for the draped (diaper?) insulation be used to basically function as the fire/ignition break for the spray foam. I am nervous about this approach and don’t want to go this way.

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  1. user-2310254 | | #1

    Your builder is obligated to meet code. But what that means varies, at least according to Martin's really informative article on the subject. ( Check it out. You also might want to contact your local code enforcement officer and see what he requires.

  2. GBA Editor
    Martin Holladay | | #2

    D. Smith,
    There are two issues here:

    1. On the interior side of the walls of an unfinished basement, does draped fiberglass insulation over closed-cell spray foam meet code requirements?

    2. Is it reasonable for a homeowner to assume that a contractor hired to install closed-cell spray foam on the interior of basement walls (in an unfinished basement) will necessarily include studs and drywall at not extra charge?

    Briefly, I think the answer to (1) is yes and the answer to (2) is no.

    Concerning question (1), you'll have to check with your local code official, as Steve wisely suggested. Fiberglass insulation is an ignition barrier, so the main question is: Does your local code require a thermal barrier or an ignition barrier in this location? Only your local code official can answer that question.

    Unless you have construction documents that state that the insulation job will include the installation of studs and drywall, I think that your contractor is reasonable to inform you that there will be an upcharge for studs and drywall.

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