Rigid foam insulation consists of panels sold in 4-by-8-foot sheets in thicknesses from 1/4 to 2 inches. It is also sold in large bundled panels, joined at the ends in accordion style, for use as ...

Q. I am currently installing rigid foam insulation around the exterior of my foundation. I’m installing 3 inches of it to a depth of 10-13 inches below grade to keep the heat in and the cold out.

Fasten two plates to each box side with 1-inch No. 8 bolts, washers and nuts. Cut pieces of rigid foam insulation to line the box interior. Glue the foam to the plywood using construction adhesive.