How to Insulate Basement Walls

Materials Needed to Insulate Basement Walls

Homeowners have access to a number of materials that can be used to insulate a basement from the inside. The ty­pe ­of insulation and the installation process should be driven by climate, the best way to control moisture in that particular climate and the basement configuration itself.

Here are a few options:

  • Blanket insulation -- This is the most common type of insulation; it is made of flexible fibers, most commonly fiberglass. It comes in batts, rolls or blankets. Some come with a facing attached that's made from kraft paper, foil or vinyl. Widths typically come in standard sizes of wall studs. Batts are typically 4 feet (1.22 meters) or 8 feet (2.44 meters) long. Rolls can be hand-cut and trimmed to fit. Blankets come in rolls as large as 64 feet (19.5 m). Standard fiberglass blanket insulation will usually have an R-value from 2.9 to 3.8 per inch (7.36 - 9.65 cm) of thickness. This type of insulation is typically cheaper than foam board, loose fill and spray-applied insulation.
  • Rigid foam board insulation -- This is made from polystyrene, polyisocyanurate (polyiso) and polyurethane. R-values run between 3.8 to 5 per inch of thickness for boards made from polystyrene. Foam boards made of polyiso and polyurethane offer higher R-values, from 5.6 to 8 per inch of thickness. The advantage of foam board is that it can keep water vapor in its gaseous state, keeping it from condensing on the wall. Foam board must be covered with a fire barrier, typically a half-inch (1.27 cm) gypsum wallboard.
  • Loose-fill insulation -- This method uses small particles of fiber or foam that can conform to any space. It can be installed by pouring it or blowing. Cellulose, fiberglass and mineral wool are common ingredients of loose-fill insulation. R-values range from 2.2 to 3.8 per inch, with fiberglass being on the low end and cellulose being the most efficient. The key to installing this type of insulation is achieving the proper density and getting complete coverage.

To learn about the benefits of insulating basement walls, read on.