How to Install Rigid Foam Insulation on Concrete
When adding insulation to concrete applications such as foundations, walls, and slabs, one of the more highly recommended forms is rigid foam insulation. One advantage to the novice, who has neither the equipment, the tools, nor experience to install foam insulation, is that rigid foam insulation can be installed very simply. For guidance and instructions, just follow the five steps below.
Step 1 - Prepare your Wall Surface
Before attaching the insulation, use a solution of detergent and water to wash the concrete surface. If your surface has cracks, cover those that are small with a commercial crack repair product. If the cracks are wider than ¼ inch, clean out any dust or debris from the crack with compressed air, then fill with the crack repair. Finally, apply a water seal to the surface, if the surface has not already been sealed.
Step 2 - Furring Strips
For concrete basement walls where you plan to install furring strips for drywall, install the furring strips before gluing the insulation panels to the wall. When you have the furring strips attached, measure and cut the insulation panels to fit between the furring strips. After applying your adhesive to the wall surface and attaching the panels, you'll need different spacing for your masonry screws to adjust for the furring strips.
Step 3 - Measure and Cut the Insulation
First, measure the width of the insulation panel and make a note of this figure. Then, at the surface where you plan to attach the insulation panel, measure to be sure there will be enough space to attach the insulation panel. If there is not space enough, you'll need to cut the panel to fit the space on the concrete surface. To cut a straight line on the insulation panel, use a straightedge and pencil to draw a line, or snap a line with a chalk box. Cut the insulation panel with a circular saw or handsaw.
Step 4 - Apply Needed Waterproofing
If the concrete surface is the interior surface of an exterior wall, and if you need to apply waterproofing to the wall, do it now before going to the next step.
Step 5 - Apply Adhesive
Apply the adhesive to your concrete surface at a time when you can do the entire surface to which you'll be gluing your panel. Work quickly so the glue doesn't dry before you're ready to attach your panels.
Step 6 - Attach the Insulation Panels
Against the concrete surface with the still-wet glue, place the insulation panels. When the entire surface is covered with the panels, measure vertically down one panel so that a mark is made every 24 inches. At each mark make a horizontal line using a carpenter’s level. Then, along these horizontal lines, make a mark every 24 inches. At each of these marks drive in a self-tapping masonry screw and washer to secure the panels against the concrete surface. If you need to protect these screws and washers from rusting, cover them with fiberglass tape.