Install rigid foam insulation between the studs in new construction by cutting each piece to fit using a box cutter, table saw or circular saw. Press it into the cavity so that friction holds it in place. Use expanding foam or caulking to seal around the edges. Foam insulation always requires covering on all sides with other building materials as it is highly flammable.
Add rigid foam insulation directly to concrete, brick or block walls using construction adhesive to glue it into place. Outline the panel with the adhesive and then add a bead between opposite corners, forming a large X. If adding siding or other covering to the outside of the wall, sandwich the insulation between the two materials. For use in basements, glue the insulation in place and cover it with at least 1/2 inch of drywall. Use expanding foam insulation to seal any joints between the panels of insulation before covering the material.
Some foam panels include a foil or plastic covering to reduce the evaporation of the gases that from the bubbles and provide the materials insulating properties. When installing covered panels, install the covering toward the inside of the home for interior installation and toward the outside of the building for exterior installation.