Should I Insulate an Underground Basement?

Identification

• According to the United States Department of Energy, a properly insulated basement will reduce your heating and cooling costs each month. However, the actual amount of savings depends on factors such as your lifestyle, what type of heating and cooling system you have, the current cost of fuel and the climate where you live. Underground basement insulation must have moisture control methods to work effectively.

Types

• Blanket insulation is widely available and often is used in basements. This type of insulation is constructed from natural fibers, fiberglass or mineral wool. Blanket insulation typically comes in batts and rolls in a variety of widths. Many manufacturers place vinyl or foil kraft paper on one side of the insulation to retard moisture. Another type of insulation used in underground basements is rigid foam board insulation. This type of insulation provides adequate insulation when installed on basement walls and ceilings. Rigid foam board insulation comes in rigid panels and is made from polyurethane or polyiso.

Advantages/Disadvantages

• Insulation in your basement reduces condensation and heat loss, keeping your home at a comfortable temperature. Placing insulation in your underground basement also slows heat loss through the foundation. When your basement is properly air sealed, insulation reduces the amounts of air leaking in and out of your basement, which lowers indoor humidity. There are a few disadvantages when installing underground basement insulation. Insulation is often expensive to install and is not efficient if installed improperly. If moisture is a problem in your underground basement, mold could begin to grow. Mold growth can cause serious health problems for those exposed to fungal mold spores. Excessive basement moisture also can cause structural damage to your home that requires costly repairs.

Considerations

• Before adding insulation to your basement, seal all gaps where air can come in or out of your home. Caulk all small gaps and place strips of foam board insulation over larger gaps. If the drainage around the perimeter of your home is poor, water could leak into your basement and soak your insulation. Once insulation is wet, it is less effective. Check the lot your home is built on to be sure the ground is sloped away from your home for proper drainage. Some types of insulation must have a fire-resistant covering to comply with local building and fire codes. Check with your county building department about building codes before installing your insulation. If you have insulation installed by a contractor, always get at least three written estimates before selecting a contractor.