Cellar Ceiling Insulation Procedures

The Controversy

• Insulating a basement ceiling is one of the poorest investments a homeowner can make, according to Tim Carter, owner of the website Ask the Builder. Insulation is expensive, and the investment return from an insulated ceiling is so insignificant that it may be decades before the homeowner sees any savings in energy bills. The basement is considered a connected space to the other living areas of the home, and insulating the ceiling cuts off the basement from the first floor. Some municipalities following the International Energy Conservation Code require homeowners to insulate unconditioned, or uninsulated, basement ceilings in new construction.

The Procedure

• Most basement ceiling insulation consists of fiberglass batting hung between ceiling joists. Paper-backed batts are stapled between the joists. Unfaced batts are held in place with wire strung perpendicularly across the joists. Installation is arduous, as the installer must frequently work his way around impediments between the joists, such as electrical wiring, plumbing pipes and furnace heating ducts. In some municipalities, building codes forbid insulation directly around recessed lights, fan housing and electrical junction boxes. In that case, the installer must install blocking, or wooden boards, between the joists to create a protected alcove around fixtures.

The Problem

• The first floor may be slightly warmer, but the basement becomes signifcantly colder. The hot water tank must work harder to heat and maintain the water temperature. Water pipes in the basement, formally protected from freezing from first floor heat, must now be insulated to prevent pipes from bursting. Furnace ducts must be insulated as well, or energy savings will be sucked away as the metal ducts lose some of the heated air flowing through the colder ducts.

A Better Choice

• While insulation for a basement ceiling yields little benefit, the U.S. Department of Energy suggests that properly insulated basement walls offer more benefits than an insulated basement ceiling. A homeowner in a cold climate can see a yearly savings of approximately $350 when walls are insulated with several inches of exterior foam insulation. Walls are usually less expensive to insulate than ceilings, with fewer installation hassles and air leaks from objects such as ducts and pipes. Exterior wall insulation for existing homes can be extremely expensive, however, requiring excavation. For existing homes, interior insulation reaps energy bill benefits, but it requires a proper water drainage system for wet basements to prevent water damage and mold growth.