Hi GBA Community,
New build in Zone 5 and this question is for a radiant slab in my basement (not slab on grade) From all my research on GBA I see the recommendation that the 10 mil (or 15 mil – still deciding) poly go over the 2″ EPS insulation.

If I don’t plan on putting any finish flooring down in the basement for a year or two, is poly below the EPS an issue any longer? Would that year or two allow the water from the concrete to evaporate fully? I believe the finish flooring problems were the number one reason why poly was recommended over the EPS.

I’m asking because I’m looking at the products from Stego and I would hate to punch holes for the PEX rigid form staples in a product that is more expensive than a 6-mil poly. Even talking to Stego they recommended poly below the EPS for a radiant install to avoid the holes you are talking about. But in all honesty I would rather see what you all think.

Thanks