Open cell in a high humidity vented crawl space – got a callback

[Beau Thibodaux]

Had a callback in Louisiana. Client says foam is shrinking and pulling away from joists. It was open cell in a vented crawl space and the RH was hitting 85-90%. Should I have known better?

[Lisa Hutchinson]

Vented crawl space plus open cell equals bad news in humid climates. Open cell is vapor permeable so it absorbs moisture at those humidity levels. Should have been closed cell with the crawl space sealed.

[Pete Sanchez]

Standard practice in humid climates is to seal the crawl space and use closed cell on the walls. Sorry about the callback but lesson learned.

[Beau Thibodaux]

Yeah I figured as much. The GC specced open cell and I did not push back. Going to start including climate zone recommendations in every quote now.

[Rick Deluca]

Smart move. Document everything. If a GC overrides your recommendation make sure it is in the contract that they accept responsibility.

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