Best Insulation Over Concrete Slab

If your basement slab lacks sub slab foam you ll have to install the insulation above the slab.

Best insulation over concrete slab.

Spray foam for sure has uses where it is the best choice by a long shot but under a slab is not the place. 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. Install a layer of rigid foam board insulation such as styrofoam tongue and groove or styrofoam brand highload 40 depending on the loads you have the first one provides 25 psi and the second one provides 40 psi. Allow this to dry then roll out 6 mil polyethylene sheeting over the floor to provide moisture protection.

Tim healeyinstead of a conventional sleeper system to support the subflooring an uninterrupted layer of foam sits directly on top of the concrete slab. Below grade to have r 10 vertical insulation at the slab perimeter extending downward from the top of the slab to a depth of at least 2 ft. Home depot does sell the right solution for residential concrete slab insulation. When building a slab on grade eps rigid foam insulation is the most common choice of insulation for performance and cost.

This method is simple but it has. One option for insulating on top of a slab is to apply rigid foam insulation directly to the slab then install the subfloor on top of the insulation. 4 where rainfall can be heavy use a fine tooth trowel to apply cold cut back asphalt mastic over the entire slab use about one gallon per 100 square feet of floor. Foamular does not absorb water like other types of foam board which makes it ideal for below grade and under slab installations.

Foamular 250 foam board. We recommend at least 1 inch of foam board. Two layers of 3 4 inch osb subflooring then float unattached on top of the foam to provide a solid and stable underpinning for the wide board wood floors. Yet expanded polystyrene eps performs as well or better than xps and at a substantially lower cost.

In climate zones 4 and 5 the code requires certain slabs below grade slabs that are less than 12 in. If the slab has hydronic tubing the minimum r value of this insulation increases to r 15. Foamular provides r 5 per inch of thickness winter and summer. You can use either one or two layers of plywood or osb and the subflooring can either be fastened to the concrete with long tapcon screws or it can simply float above the foam.