Insulating A Radiant Heated Floor (below Slab) -- Use Foam Board? - HVAC - DIY Chatroom Home Improvement Forum

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Old 01-14-2008, 08:52 AM   #1
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Insulating a radiant heated floor (below slab) -- use foam board?

Quick question to all the radiant floor (basement concrete) experts out there.

I'm in the process of having our basement floor broken up, dropped down a foot and re-poured with a PEX in-floor heating system installed (in-floor).

Concerning the insulation *beneath* the PEX, our contractor has quoted us to use a "Reflector Pad" beneath the PEX. I'm concerned this may not be enough and am considering laying down 1" or 2" high-density rigid foam board over top of the gravel BENEATH the concrete altogether.

Can someone illustrate whether my approach is overkill? Would adding a rigid foam barrier between the gravel and concrete be necessary if a reflector pad is already in the plan to be installed beneath the PEX?

I've got one shot at having the floor built properly, and I want to be certain we're doing it right the first time.

Many thanks,


drh is offline   Reply With Quote
Old 01-14-2008, 09:13 AM   #2
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Go with the foam.


LawnGuyLandSparky is offline   Reply With Quote
Old 01-14-2008, 03:42 PM   #3
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Go with the foam but, make sure the gravel is compacted flat so you don't develope stress cracks in the new floor if it's supported unevenly.
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