Wood Floor over EPDM?

A homeowner in Minnesota is building a small 12x16 studio/shop on helical piles and ran into a question worth noting if you're ever mid-project with an exposed floor. To protect the subfloor from rain during a long dry-in period (the build started in May 2025 and wasn't enclosed until August), he wrapped the finished floor assembly in a 45 mil EPDM pond liner, a rubber membrane normally used to line ponds, to keep water out of the insulation and framing below.

Now that the structure is enclosed and he's ready to install 1x6 red oak flooring, he's asking whether to cut out that rubber liner first or simply lay the wood floor on top of it. The floor assembly below the liner includes AdvanTech subflooring, rigid foam insulation, 2x12 joists, and R-49 fiberglass insulation between the joists, all sitting on piles 8 to 12 inches above grade. The shop will be heated with a gas furnace and cooled with a window air conditioner, and the interior will be conditioned like a regular home.

This is a specific construction-sequencing question posted to a building forum, not a rule change or program update. There's no rebate or broader policy news here. It's a useful reminder, though, that temporary weatherproofing materials used during construction can trap moisture if left in place under finish flooring, something to keep in mind if you're overseeing any addition or outbuilding project of your own that gets rained on before it's closed in.