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How to Insulate Basement Walls With Batt Insulation

An uninsulated basement can be responsible for up to 25 percent of the total heat loss in your home. Even if you are only using your basement for storage, your pocketbook still benefits from fiberglass batt insulation installed against the exterior walls. Because most jurisdictions require that interior insulation be covered by drywall or paneling for fire safety reasons, frame the exterior walls with 2-by-4-inch lumber set 16 inches apart. Batt insulation is manufactured so that it fits between the studs. After installing the insulation, cover it with regular drywall sheets, which are also manufactured for simple installation on studs installed 16 inches apart.

Things You'll Need

  • Protective clothing, safety glasses and facemask
  • Expanding foam caulk
  • Caulk applicator gun
  • 2-by-4-inch lumber
  • Electric drill with masonry drill bit
  • Concrete screws
  • Screwdriver
  • Fiberglass batt insulation
  • Razor blade utility knife
  • Staple gun
  • Plastic vapor barrier
  • Construction adhesive
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    • 1

      Seal around all pipes, vents and other mechanical items that broach the exterior basement walls. Use expanding foam caulk and an applicator gun.

    • 2

      Apply 2-by-4-inch lumber. Start with one at the top of the wall just below the point where it meets the sill plate. Attach the studs by drilling holes with a masonry drill bit and securing them with concrete screws. Put additional 2-by-4-inch studs oriented vertically running from the bottom sill plate to the 2-by-4 stud you just installed near the top sill plate. Space the 2-by-4s a distance of 16 inches apart, as measured from the center of one 2-by-4 to the center of the next.

    • 3

      Cut lengths of batt insulation with a razor blade utility knife that fit the wall’s height. Measure from the bottom sill plate to the ceiling joists’ bottoms. Put the insulation into the space between the studs, orienting it so the side with the paper is facing the inside of the basement. To piece together shorter lengths of batt insulation, butt the ends up against each other.

    • 4

      Secure the insulation between the studs by stapling the insulation backing paper to the stud about every 12 to 18 inches along the height of the wall on both sides of the strip of batt insulation.

    • 5

      Cut small pieces of batt insulation to insert between the ceiling joists above their bottoms and above the topmost point of the insulation you installed. Make each piece about an inch larger than the opening it fills. Do not squish down the insulation as you install it because it loses some of its insulating properties if the air spaces it contains are compressed.

    • 6

      Install a plastic vapor barrier on top of the batt insulation. Glue it directly to the top sill plate, the 2-by-4 studs and the bottom sill plate with construction adhesive. This keeps warm, moist interior air away from the insulation, and keeps it from encouraging the mold growth. Another method of installing vapor barrier is stapling it to the 2-by-4 studs. When using this method, overlapping cuts by about 2 feet minimizes air leakage.