Best Insulation Over 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.

Best insulation over concrete slab.

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. Foamular does not absorb water like other types of foam board which makes it ideal for below grade and under slab installations. If your basement slab lacks sub slab foam you ll have to install the insulation above the slab. Foamular 250 foam board.

This method is simple but it has. 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. There are several ways to install subflooring above the rigid foam. 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.

Allow this to dry then roll out 6 mil polyethylene sheeting over the floor to provide moisture protection. Spray foam for sure has uses where it is the best choice by a long shot but under a slab is not the place. Foamular provides r 5 per inch of thickness winter and summer. When building a slab on grade eps rigid foam insulation is the most common choice of insulation for performance and cost.

Tim healeyinstead of a conventional sleeper system to support the subflooring an uninterrupted layer of foam sits directly on top of the concrete slab. We recommend at least 1 inch of foam board. When it comes to concrete and insulation contractors tend to be most familiar with extruded polystyrene xps. Use a good quality foam board adhesive to adhere the foam to the concrete.

If the slab has hydronic tubing the minimum r value of this insulation increases to r 15. Home depot does sell the right solution for residential concrete slab 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. 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.