I am building a four season room off the back side of my current home (12x16 room) and have been going back and forth about floor insulation and what hest source I want to use! I am in zone 5 in New Hampshire.

My question is where would you place the vapor barier in an elevated floor above an unconditioned space, using radiant floor heat, to not trap moisture? I found this link useful Where to place the vapor barrier in a sunroom floor

But with the in floor heating I think it may change. Here is what I think my building layers would be BUT please someone correct me!

Flooring Subfloor Radiant heat Foil faced insulation (act as vapor barrier) Batt insulation between joists Board or rockwool comfortboard insulation below joists to break thermal barrier Cap system with plywood.

Thank you!


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