Cavity walls like wood or metal can take batt or foam insulation. Solid concrete walls obviously cannot and are therefore poor insulators, transferring temperatures much more readily. However, it is possible to insulate a concrete wall using furring strips and foam board insulation. The average do-it-yourself homeowner can insulate a concrete wall in less than a day, depending on the size and scope of the project.
Attach treated two-by-fours vertically to the concrete wall using a hammer drill and concrete screws. Place the first two-by-four, working from left to right into the corner, plumbing the two-by-four with a level. Drill holes through the wood and into the concrete. Space the holes vertically and 16 inches apart. Attach the wood using flat-top concrete screws. Make sure the screws are recessed beneath the surface of the wood so the screw heads will not impede the wall covering, whether drywall or panelling. Repeat the furring across the concrete wall, spacing the two-by-fours 16 inches apart and plumbing each board.
Cut the rigid insulation with a razor knife. Mark and cut it to fit between the attached two-by-fours on the wall. You should get three sections from one sheet of insulation board, which is 48 inches wide and eight feet tall. Because the two-by-four strips placed on the wall are one-and-a-half inches thick, you can insert three pieces of insulation between. The insulation is one-half inch thick, so three pieces equal one-and-a-half inches. Use one strip of duct tape attached across the insulation and onto the two-by-four strips to hold the insulation between the two-by-fours.
Cover the wall with green, waterproof sheet rock or selected four-by-eight sheets of panelling. You can attach the wall covering directly into the two-by-four strips using screws or finish nails.
Apply a base coat of concrete sealer to the exterior of your concrete wall to prevent water seepage. Concrete walls are notorious for collecting water from a moist environment, whether from the air or surrounding soil. You can paint the concrete sealer onto the concrete as a white base coat or tinted to meet your colour needs. The concrete sealer will also provide some means of UV resistance against the heat of the sun and help prevent heat transfer to the interior of the concrete.
Cover the exterior wall with rigid insulation and tar if the wall is below the soil surface. Using a roller, apply the tar directly onto the concrete. The tar ingredients will not set up for some time, so you should be able to apply tar to the entire wall before installing rigid insulation.
Place the rigid insulation onto the wet tar wall and make sure the entire wall is covered. Use three-quarter-inch thick waterproof rigid board on the exterior. It is also helpful to use rigid board with a thermal barrier applied in the form of a reflective layer facing outward. The thermal barrier will deflect heat during the summer and retain it during the winter.
Things you need
- Hammer drill
- Concrete screws
- Treated two-by-fours
- 4x8x1/2 rigid board insulation