How to Insulate Your Basement Floor

Insulating a basement adds comfort and energy savings. In a basement space, there are two areas where energy efficiency can be improved with EPS rigid insulation, immediately affecting the comfort of the room for the better: the floor and the walls. While Plasti-Fab has a variety of insulation solutions for these applications, this guide covers the use of PlastiSpan Insulation to insulate the floor.

Follow these simple how-to steps to install PlastiSpan Insulation, put an insulated subfloor in place, and be ready to install the final floor finishing such as carpeting, tiles or linoleum.

Before doing anything, be sure to reference the building code requirements applicable in your region.

Usually a moisture barrier is required: cover the entire floor area with 6-mil poly. Do this to eliminate any moisture migration. (HINT: To limit the cutting of PlastiSpan insulation, plan the area to include 2x2 strapping across the floor in one direction.)

Following the installation of the moisture barrier, attach perimeter nailers around the space. Use a nailer that is the same thickness as the insulation. Attach the nailers around the perimeter using self-tapping concrete screws penetrating the concrete as per the screw manufacturer's recommendations.

Now install the PlastiSpan insulation. Cut the first row of insulation to a 21-3/4" width. Cut subsequent rows to 22-1/2" widths. Use the insulation cut as guides to place successive rows of nailers at 24" on center. Continue on to the opposite wall.

With the floor insulated with PlastiSpan insulation, prepare to lay the subfloor. Make sure to use an appropriate subfloor material that will support the span. Check with a building supply dealer before purchasing it. It's easier to snap chalk lines across where the strapping is to ensure the subfloor material is placed squarely.

It's time to secure the subfloor. Be sure to stagger the subfloor joints for extra stability. (HINT: Rent an automatic nailer, screw gun or automatic screw gun to make the job easier.) Secure the subfloor by adding adhesive to the strapping (use PL300), then fasten the 5/8"" subfloor directly to the nailers as per the subfloor manufacturer recommendations.

The basement is now properly insulated and ready for the finished floor. The finished floor will feel noticeably more comfortable right away, creating a space the family will want to spend time in, without two pairs of socks on their feet.