Vapor barrier under concrete floor
We are building a home with a suspended 4” concrete floor. The subfloor is 1-1/8” plywood and will be covered with 1” rigid foam prior to the pour. We plan on taping the seams of the rigid foam. We are installing radiant floor tubing, with fasteners that will penetrate the foam and attach to the subfloor. The floor is over a conditioned crawl space, which will have its own HRV system. The ground of the crawl space will be covered with a 10mil vapor barrier. There will be batt insulation between the floor joists. We are wondering if there is any reason to lay down a vapor barrier between the subfloor and the rigid foam, given that the vapor barrier will be penetrated repeatedly by the fasteners.
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