One Concrete Slab, Two Vapor Retarders
Last year we poured a new basement slab in NJ, following the excellent advice on this forum.
Under the 4-5” slab we have a polyethylene vapor barrier, then 2” rigid insulation, then 6” stone and drains.
Now we would like to install natural stone tile on top of the slab. We are planning to install Schluter Ditra on the slab, then the 1/4” tile. But I’m wondering if putting Ditra, which is apparently a vapor barrier, over the slab will cause problems due to moisture being trapped between it and the vapor barrier below.
Is it ok to put Ditra over a slab that already has a vapor barrier?
Thank you in advance!
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