After that thin furring strips are installed on top of the foam to provide a firm base for the drywall screws and drywall.
How to insulate concrete walls with foam board.
The correct method of using rigid foam is to run continuous 4 foot by 8 foot sheets of the foam across the concrete basement wall making the rigid foam the de facto wall.
Use a straightedge and a utility knife to slice through the insulation then snap the board along the cut line to get a.
Lay a panel of polystyrene.
Cut each sheet of rigid foam insulation to fit the crawl space wall height.
The insulation may be rigid board extruded or expanded polystyrene or polyisocyanurate closed cell spray polyurethane foam cellular glass fibrous batt or fibrous blown in insulation note however that fibrous insulation is susceptible to moisture.
After the adhesive cures add extension boxes to the outlets and switches and spray foam into every gap top bottom and around each box.
The moisture drive in a basement is from the interior to the exterior so the spray foam prevents any condensation or mold growth while providing the highest r value per inch 6.
If necessary address moisture problems and seal cracks before you begin.
Interior insulation refers to insulation applied to the interior side of the concrete masonry as shown in figure 1.