We are remodeling our house and putting in a wine cellar in the basement. The house has radiant heat (water temp approx 112 since it is geothermal) and so there are heating coils running in the bays above the ceiling of the room. Right now we have R19 foil faced fiberglass insulation with the foil facing the radiant with a 1 in air gap. My question is: Will the foil facing provide enough of a vapor barrier - there will be a large temperature differential between the space above and the wine room below (112 vs 57 degrees). I had thought of adding 6 mil plastic sheathing before the fiberglass but was not sure if it was okay to go next to the radiant heat. Do you think this is sufficient?

An energy star consultant had said we should consider putting rigid board insullation below the fiberglass facing the wine cellar but this will cut down on an already low ceiling and we do not know whether we should be putting a vapor barrier below the fiberglass.

Any suggestions or advise would be greatly appreciated.