How to Insulate a Basement to Prevent Mold
- 1). Attach extruded or expanded polystyrene insulation foam sheathing to the foundation walls. Use extruded polystyrene if you require a sheathing that is more moisture tolerant.
- 2). Tape all the wall joints with a tape suitable for sealing weather-resistant barriers to keep moisture and air from penetrating the wall cavity.
- 3). Use can spray foam to seal the top and bottom of the polystyrene insulation foam sheathing.
- 4). Install a piece of composite decking at the very bottom of the wall to protect the wall in case any water leaks into the basement.
- 5). Use a pressure-treated wood to frame the wall. Nail the top plate into the first floor joists then the bottom plate into the composite decking. Use a builder's level to make sure that the framing is straight.
- 6). Use your choice of fiberglass insulation, spray foam insulation or wet-spray cellulose insulation to fill the stud wall cavity.
- 7). Decide whether or not to install vapor barrier. According to the U.S. Department of Energy, a vapor barrier should not be installed on the interior side of a basement wall if the wall has been externally insulated. Home Construction Improvement suggests using a vapor barrier if you've used less than 1 1/2 inches of foam to insulate your walls.
- 8). Install a finished wall surface such as drywall to cover your basement walls.