Uninsulated slab and hardwood flooring
I’m renovating a small outbuilding on a farm (15′ x 15′), which has slab on grade foundation. The slab is sitting on crushed stone but has no vapor barrier underneath. I have put a 10 mil poly sheet on top of the slab, and 2×4 joists (sleepers) on top of the poly sheet.
My plan was to now spray foam insulate (about 2″ – 3″) on top of the poly sheet, then install subfloor and then hardwood.
However, before spray foaming, I can see significant water pooling under the poly sheet. Probably to be expected, but somewhat surprised at how visible. With these details, is the original plan (spray foam over poly) sensible — (with the goal being to thwart the entry of all water/vapor)? Or, is another vapor permeable approach a better way to go? Or dimple plastic? Any advice welcome.
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