Rigid Insulation Under Basement Slab

Tape the joints between the boards with builder s tape.

Rigid insulation under basement slab.

As the slab will only be able to dry upward the slab should be allowed to dry before finishes are applied. You want to create a tight insulation layer. A careful evaluation of these materials performance attributes against the project s needs can dramatically shrink labor and material costs. For under slab applications the rigid foam insulation typically should be installed over a gravel base with a poly vapor diffusion retarder between the gravel and insulation.

When slab insulation is provided a sheet polyethylene vapor barrier should be located over the rigid insulation and in direct contact with the concrete slab. R 7 7 rigid foam insulation model 310891 18 35 18 35. Place a 1 inch layer of 4 x8 extruded polystyrene foam board over the gravel covering the entire floor area. If the foundation is on frost susceptible soils install a layer of impermeable insulation horizontally in the soil at a slope ratio of 1 5 for at least 1 m 3 ft.

View the owens corning basement and crawlspace insulation 48 78 48 78. Dupont styrofoam brand extruded polystyrene foam insulation is an ideal solution for under slab installations offering the following advantages. Reduces energy loss between ground and concrete slab reduces potential for condensation and moisture damage high compressive resistance can sustain heavy loads without damage. Evenly spread the base gravel under the basement slab keeping it 1 inch lower than the conventional method.

Get free shipping on qualified under slab foam board insulation or buy online pick up in store today in the building materials department. Insulation located below grade as required in climate zones 4 through 8 should extend the length specified in the table by any combination of vertical insulation insulation extending under the slab or insulation extending out perpendicular to the building insulation extending perpendicular away from the building should be protected by pavement or by not less than 10 inches of soil. Insulation is applied to houses with slab on grade foundations exactly as you would insulate the outside of a full basement see section 6 1 insulating the basement from the outside.