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Insulating a corrugated metal floor deck

P-stone | Posted in General Questions on

Hi –

I have a garage on a sloped waterfront lot in zone 6a (lots of moisture). The cement garage floor was poured on top of a corrugated metal floor deck held up with steel I beams. Under the main garage floor is a decent space that I’d like to finish and heat (unsure if I’ll ever heat the rest of the garage). Spray foaming the underside is one option I would assume but its costly. Would polyiso foil faced boards be an option if the seams were well taped or foamed?

Very much appreciate this forum and any feedback!

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  1. GBA Editor
    Martin Holladay | | #1

    Q. "Would polyiso foil faced boards be an option if the seams were well taped or foamed?"

    A. Yes. If possible, the insulation layer should be continuous -- so that the ceiling insulation meets the wall insulation without any thermal bridges.

    Don't forget that rigid foam needs to be protected with a layer of drywall for fire safety.

    -- Martin Holladay

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