Steps in Insulating Concrete Basement Walls
Insulating concrete basement walls are an important source of heat loss in buildings. Exterior insulation of a basement wall is the best way to make it more efficient. Insulation during construction takes advantage of the fact that the walls of the basement are exposed. Applying rigid foam sheets on the outside of the walls prevents cold air from penetrating the wall material. Rigid foam insulation sheets can be purchased at the hardware store and home improvement stores. Ask him what size and type are best for his particular application.
Apply to the face of a 2 by 8 feet sheet of rigid foam insulation 2 inches thick. Place the adhesive in small drops on a grid with each blob separated by about 12 inches. Press the rigid foam sheet against the outer face of the wall, with the blade in an upright position. Cut the sheet out so that its top is the top of the basement wall. Also, cut a sheet of foam lengthwise to fit the remaining wall space when you reach the end of a wall. Cut around door and window openings with a sharp knife after the foam has been fixed to the wall.
Cover the joints between the foam sheets with construction adhesive tape. Apply the foam sheets together with rigid tape act as a vapor barrier, so no plastic vapor barrier is necessary. Fill around the basement walls, being careful not to disturb the sheets of rigid foam or place any large or strong rocks against them. Rigid foam is impervious to water and moisture, so the soil can be padded against it without damaging it.