Hello all,
I want to add some stryofoam insulation over the subfloor and under the concreteboard to improve the electric radiant heating system in a bath remodel. I have the space to possibly add 2″ thick styrofoam. Do I need to add stringers to support the concrete board, or can I simply screw down the concrete board through the styrofoam to the floor framing? Will the concreteboard and tile displace weight enough to keep the styrofoam from crushing? If I add stringers can I space them 24″ apart?
Thanks
Jim
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Jim,
I don't know about a tile application, but I put Styrofoam under all of my heated slabs and didn't have any crushing. I designed the garage floor to withstand 6,000 PSF and have pulled smaller tractors in there without any issues.
I would guess that you would be fine in your application, but if you are real worried about it, grab a piece of foam, put it on the floor in question with the cement backer on it and jump up and down on the backer board. I don't think you will crush the foam. I would be more concerned with flexing of the underlying floor.
Steve