We have hydro radiant under hardwood.

We would like to put a couple of area rugs in our open floor plan to section off functional areas.

Should we use non-chemical materials such as wool or cotton to avoid out-gases?

What material should we stay away from?

Are there rug backings we should look for or avoid?

I'm assuming that having a mat under the rug should not be used as it would dramatically increase the Rvalue, reduce breathability and harden or negaively impact the rug/mat/wood floor when heated by the radiant heat.

Can anyone provide some insight?

I dont think so...your floor area rug will not have any negative impact if you place a rug pad..underneath your rug..as rug pads(mats) are used to protect your the rugs from unwanted dirt and other stuff..

This message has been edited. Last edited by: PotterPop,

I would say for that you` should use different types rugs. Initially put rug pad thereafter place which ever rug you like.

natural fiber rugs

This message has been edited. Last edited by: Lewis Peterson,

I wonder whether the rug will act as an insulator and stop heat from getting into the room. I also wonder how much the trapped heat will affect the wood floor and whether the resulting shrinkage of the wood will open gaps at the joints

I would call the radiant heat manufacturer and ask these questions.