What thickness of insulation and concrete do you recommend in a floating slab?

Marc-Andre Roy
Updated: April 21, 2021

I am building a concrete radiant floor system for a new build in Quebec. The contractor will build a floating slab with footings. The contractor is suggesting 2 inches of insulation and 3 inches of concrete, which seems too little base on what I have read. What do you recommend the thickness to be for the insulation and the concrete for the slab and radiant floor system? Thank you.

Responses (3)

Marc-Andre Roy
Marc-Andre Roy 3 years ago
Rj Pierson 3 years ago

I second everything Emmanuel says. Extra insulation costs very little, and if it's sat on a good drained layer of gravel to prevent frost heave it's the best value for money you can have in a build. And, personally, I would never consider anything under 4 inches of reinforced concrete for a slab on grade foundation - maybe using Helix micro rebar?