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Community and Q&A

Closed-cell spray foam insulation under a sunporch

Denise P | Posted in Building Code Questions on

We installed 2 inches of spray foam closed cell insulation on the underside of a sun porch which is open on a sides underneath. My husband wants to store his riding lawn mower underneath which means he will have to drive it under the porch and start it up under the porch. I understand that this foam is highly flammable. Please advise if this is safe or what we can do to ensure safety of the storage of the riding mower. Thank you.

Denise P

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  1. [email protected] | | #1

    If you're concerned about the inflammability of the foam, look into intumescent coatings.

  2. GBA Editor
    Martin Holladay | | #2

    Spray foam is a fire hazard, and it should always be protected with a thermal barrier or an ignition barrier. In this location, I suggest that you protect the cured spray foam with 4x8 fiber-cement siding panels, cementitious underlayment (the type of underlayment used under tile), or plywood.

    The spray foam contractor who installed the foam should have been aware of the hazard. It is a building code violation.

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