Rigid Foam Under Subfloor

Lay sheets of high density rigid foam over the polyethylene.

Rigid foam under subfloor.

Basement subflooring has so many jobs at hand. With a rigid core plank you can add additional underlayment under the planks however i would keep it at 2mm or under. Most people do not think about insulating their floors unless perhaps it s their attic floor. Rigid foam insulation.

Thinking outside the slab one solution would have been installing rigid insulation under the slab turning it up on the perimeter to form a giant pan and then casting the concrete slab inside the pan. The right kinds are even dense enough to support a plywood subfloor without any supporting wooden strips underneath. But insulating your floors is a good idea for many reasons including energy efficiency and height adjustments. Lay rigid foam.

For the pool table you will still float the floor normally. Use a utility knife to cut the foam to size a hacksaw or drywall saw also work well for this. You simply lay sheets of foam on the basement floor then fasten 5 8 plywood on top with concrete screws driven into predrilled holes in the floor. The top layer of subfloor steps back and gets a layer of peel and stick flashing tape to form pan flashing under the sliding doors.

One install was 4 of blue foam with woven wire mesh and radiant floor heat with 3 of concrete first and 2 of bluestone and setting bed over it. Rigid foam makes a great basement floor insulation. Tape the seams of the foam panels with heavy duty construction tape. Leave a 1 4 inch gap around the perimeter.

Rigid foam is a nice option because it provides an excellent thermal break between concrete and flooring. The other was 2 of blue foam over a concrete slab with a layer of 2 x2 squares of osb with plastic dimple board as a floating floor over the foam. Unlike above grade sub flooring basement sub floor has to do all of the usual things and more.