Best Under Slab Insulation

When building a slab on grade eps rigid foam insulation is the most common choice of insulation for performance and cost.

Best under slab insulation.

Of these two materials green builders prefer eps because eps is manufactured with a more environmentally benign blowing agent than xps. Q how much insulation is necessary under a typical radiant slab. The ground is cold compared to air temp even in the summer. The f factors for slab on grade floors are defined in standard 90 1.

A john siegenthaler a consulting engineer who specializes in hydronic heating system design responds. Spray foam for sure has uses where it is the best choice by a long shot but under a slab is not the place. R 10 scored squared edge insulation sheathing model 52dd view the owens corning basement and crawlspace insulation. R 10 scored squared edge insulation sheathing model 52dd view the owens corning basement and crawlspace insulation.

I wouldn t go as far as saying you couldn t use spray foam below a slab but i m not sure why you d want to. Best seller owens corning foamular 250 2 in. Continuous insulation extends downward from the top of the slab and along the entire perimeter and completely covers the entire area under the slab. For more information on this issue see choosing rigid foam.

Incomplete slab insulation unlike monolithic slabs stem wall slabs can be insulated from either the inside or the outside. Downward heat loss from a radiant slab should not exceed 10 percent of upward heat output a ratio derived from european installation standards for floor heating systems it s possible to calculate the r value needed to meet. Best practice of insulating the stem wall perimeter and under the slab will help achieve the lowest hers scores. It will help in the winter obviously.

For example with a forklift load on a typical 4 inch thick slab one calculation would indicate that 32 psi is applied to the insulation compared to only 2 5 psi under a more accurate calculation. Best seller owens corning foamular 250 2 in. Is it worth it to insulate under a concrete slab. In climate zones 4 through 8 the most common locations for insulation are at the perimeter of the slab installed vertically and under the slab installed horizontally.

The most common insulation materials for use under a concrete slab are extruded polystyrene xps and expanded polystyrene eps. Buried horizontal or sloped wing insulation installed around the exterior perimeter of the building to raise soil temperature. Insulation under the slab will help the floor stay warmer even in the summer time.