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do you need insulation under a radiant slab

mikedo Member Posts: 174
as it says in title do you need insulation under a radiant slab


  • Snowmelt
    Snowmelt Member Posts: 1,399
    Answer hell yea , otherwise you will be heating up dirt / sand or earth
  • hot_rod
    hot_rod Member Posts: 20,809
    If not some of your heat energy $$ goes down into the earth. How much and how quickly depends on the soil below moisture, conductivity, etc

    No amount can stop the energy movement, 2” seem to be the amount that most codes require 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • HomerJSmith
    HomerJSmith Member Posts: 2,309
    Heat energy travels in a straight line to what ever is coldest. Up, down, or sideways. Especially so if in bedded in concrete. Use high density foam board, not the bubble wrap stuff.