by Pete
(Alaska)
Q. I am building a house and want to use concrete instead of gypcrete for my radiant floor heating system. Can I pour concrete right on my sub floor or do I need a barrier of some kind?
A. You can pour the concrete right on the sub-floor. We do many of these floors using 3000 psi 3/8 stone concrete at 1.5 inches thick up to 3 inches thick.
Concrete weighs 17 - 18 pounds per square foot at 1.5 inches thick and 25 pounds per square foot at 2 inches thick. You just need to make sure your sub-floor can handle the weight.