What is the minimum R value of the insulation needed under a radiant slab application?
What is the minimum R value of the insulation needed under a radiant slab application? 1 a minimum R-10 (in units of h·ft²·°F/Btu) perimeter insulation but if it's heated an additional R-5 is required with the height/depth subject to climate zone. For commercial buildings, edge insulation of R 7.5 to R-20 is required for all heated slabs again depending on climate zone. How thick should concrete be for radiant floor heating? Radiant heat can be used in slabs as thin as 1.5" (such as in cases where it's placed over existing floors). However, for new construction, the slab should be...