Insulation, Radiant and Vapor Barriers - Help- installation question

Hello,

I am installating fiberglass insulation r-38 under a suspended radiant PEX heating system that is attached to the subfloor below my hardwood floors.

My question is : does it matter if I mount it paper side up or paperside down and staple the paper to the joists. Paper side up (facing the heat) would require me to use hangers to hold up the insulation right?

Thanks for your answer.

Mark

The purpose of the paper is to prevent condensation problems.

What condensation problems do you forsee?

What climate are you located in.

Paper side down would be intended to prevent condensation in hot humid climates.

Paper side down would cause condensation problems in cold climates, but would prevent summer condensation problems.

Paper side up wouldn't do anything in cold conditions, but would allow condensation in summer conditions.

There are other solutions. That don't involve batt.... ;)

Thanks Doug.

I live in NE and this is a re-install due to a PEX leak problem but the heating guys are telling me that the insulation guys should have hung the insulation paper side up. It was installed paper side down and I'm trying to check on who is right?

I assume that I then would need to put up plastic to form a vapor barrier on the exposed side?

I should have told you that this is in an uninsulated basement. i.e. no wall insulation just cement foundation walls and floor.

Thanks, Mark

There is no right way with paper facing / VDRs. All you can do is pray that you've done a poor enough job to allow condensation to dry once it's formed.