After my home energy audit with Mass Save a few weeks ago, I decided to insulate the floor joists in the basement. The floor joists are where the wooden frame sits on top of the concrete foundation — near the ceiling in my basement. In many old homes, this space is not usually insulated, which invites cold air and bugs into the home. Insulating this space will make the home a little more energy efficient and help keep bugs (and mice) out.

The job is pretty straightforward. Buy rigid insulation with an R5 or R6 value, a puddy knife, sharpening file & Great Stuff foam insulation.

1). Measure the joist area to be insulated.

2.) Sharpen the edges of the puddy knife with the file.  Using the puddy knife (or large box cutter or circular saw), cut the rigid insulation to size.

3.) Fit the insulation into the joist and use Great Stuff to seal the perimeter. Great Stuff will harden in a few minutes.

Reminder: USE GLOVES! Great Stuff is impossible to get off your hands. Turpentine, nail polish remover, even gasoline will not get it off. Be careful of nails in the ceiling. If one of these goes into your head — you will need a priest, not a tetanus shot.