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Community and Q&A

Insulating a vented crawl space without encapsulation?

scottbob4 | Posted in Energy Efficiency and Durability on

The house is along the jersey shore and had water in the crawl space during hurricane sandy but is usually dry. It is a vented on three sides and has never had insulation or moisture barrier on the ground. it has a dirt floor and is approximately 2 and half feet deep. The house was built in 1971 and shows no signs of mold in the crawl space. There are no ducts in the crawl space but there are some water pipes and the baseboard heating pipes between some joists.
I would like to keep the crawl space vented, because of possible flooding it doesn’t seem to make sense to try and encapsulate the crawl space.
Does it make sense to add fiberglass insulation between the joist and then put foam board nailed into the joists below it as a thermal break and moisture barrier. Would this keep the insulation dry or just trap the moisture in the fiberglass

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  1. GBA Editor
    Martin Holladay | | #1

    Your suggested approach can work, especially if the rigid foam layer consists of foil-faced polyiso with carefully taped seams.

    For more information, see How to Insulate a Cold Floor.

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