Attic

Courtesy of energystar.gov

The attic is one of the places where you often find the biggest air leaks, which can increase your energy bills and make you uncomfortably hot in summer and cold in winter. It is also a place that is generally accessible, making it easier to air seal and insulate to improve your home's comfort and overall energy performance.

Attic Ventilation
Proper ventilation of the attic with natural air flow keeps the roof deck cool and dry, extending the life of roof shingles and preventing ice dams without using the energy needed to run an attic vent fan. Be sure attic soffit vents and gable vents are not blocked so air flows freely through them. Some homes have ridge vents or vents through the roof deck instead of gable vents. Learn more in the Guide to Home Sealing (2MB).

Duct Sealing
Seal duct connections and seams with duct sealant (also called mastic) or foil-backed tape to reduce leaks. In unconditioned areas, like attics and some basements, wrap ducts in insulation (R-6 to R-8 is recommended). If your ducts are in the attic, you also can cover them with blown insulation. » Learn more.

Chimney Sealing
Seal hidden air leaks to make your home more comfortable and energy efficient. Always find and seal air leaks before adding more insulation. Chimneys or furnace flues that penetrate your attic floor have holes or gaps around them that can allow the air in your home to escape through the attic, increasing your energy bill and causing more drafts. Around chimney and furnace flues that can get hot, cover the gaps with metal flashing and caulk small gaps with high temperature caulk. Learn more in the Guide to Home Sealing (2MB).

Plumbing Stack Sealing
Plumbing stacks, vents, ducts, or electrical wires often have holes or gaps around them that can allow the air in your home to escape through the attic, increasing your energy bill and causing drafts. Seal small gaps with caulk and seal holes up to 3 inches in diameter with spray foam. Cover spaces larger than 3 inches with a piece of foam board and seal with spray foam. Learn more in the Guide to Home Sealing (2MB).

Weather-strip and insulate your attic hatch or door to prevent air from escaping out of the top of your house.

Air sealing is simply using caulk, spray foam, or pieces of rigid foam insulation to cover or seal holes, cracks, and gaps where air can pass into or out of your home. Sealing those air leaks will help reduce drafts and help get the full performance from insulation. After air sealing, check if you can see the tops of your attic's floor joists (insulation is not covering them). If so, adding more insulation will likely help lower energy bills. Insulation is designed to resist heat flow - that is, if it is hot outside, insulation greatly reduces the amount of heat you can feel inside a house. Or, if it is cold outside, insulation helps reduce heat losses through the ceiling. Insulation works best when air is not moving through or around it. Therefore, it is very important that air leaks be sealed to ensure that you get the full performance out of any insulation installed. To get the most savings, the easiest place to add insulation is in the attic. Get our Guide to Home Sealing (2MB) and learn how to seal and insulate your attic and reap benefits for years to come.