Air leaks are a major source of wasted energy and poor indoor comfort. Sealing them can help to reduce your heating and cooling costs, as well as improve indoor air quality.
Many home air sealing projects are easy for homeowners to do themselves. For example, basement walls and outlets can be easily sealed with caulking or spray foam.
Attic
Upgrading your attic insulation is one of the best ways to reduce energy bills and improve comfort while maximizing home efficiency. But be prepared for a messy, time-consuming project. It’s essential to wear protective clothing, masks or a half-face respirator to protect yourself from the dust and fiberglass that will be kicked up as you work.
Before you venture into the attic, make a sketch of the attic floor plan to help locate soffits, stairwell openings, ductwork and other dropped-ceiling areas that are major sources of air leakage (Photos 1 & 2). You’ll probably have to scoop back up existing insulation in these locations.
Unsealed attic gaps let conditioned air escape up through the living space and pull hot exterior air into the house in winter. In summer, the opposite happens; cooled attic air flows down to living spaces while hot outdoor air moves into uninsulated attics.
Fill small holes and cracks with caulk or expandable foam spray. Seal around the attic hatch or door with caulk or a pre-made insulated attic stair cover that rests right over the pull-down stairs. If you have scuttle holes for attic access, close them with caulk and install pre-insulated hatch covers made from lightweight SilverGlo foam insulation. Use hooks and fasteners to securely fasten the cover. If your attic has a slope, you can add batting or blown insulation to raise the depth of the attic and help reduce air flow through the soffits.
Windows
Windows are often the culprit of air leaks that can be costly to your energy bill. These leaks allow warm summer air to escape and cool winter air in, causing shifts of temperatures throughout the home.
Luckily, this problem is easy to fix. Using caulking and weatherstripping, you can seal these gaps and prevent cold drafts from entering your home during the winter.
First, use your eyes to visually inspect the windows for leaking areas. If you turn off the indoor lights during the day and hold a flashlight against the window frame, you should be able to see daylight shining through any cracks or gaps. You can also use the light test with a candle. Light the candle and trace along the edge of the window, if the flame flickers when you pass by a gap this means air is passing through.
Next, use a caulking gun to apply the caulk to any visible leaking areas. You can also use the same technique to caulk around other leaking areas such as recessed lighting, vents, chimneys, pipes, electrical outlets, and the area where your porch or deck connects to the house. This is one of the easiest ways to improve your home’s energy efficiency and reduce your energy bills. It’s also a cost-effective way to keep warm air from escaping your home during the winter.
Doors
Older homes often have doors that don’t seal well. Inspect the weather stripping for signs of wear and tear, or consider replacing it entirely with pliable foam sealant designed for use around doors. Also, replace any leaking exterior doors with energy-efficient models.
If the door leads into unconditioned spaces, such as a garage, or an interior room without insulation, it should be sealed with caulk and/or expanding spray foam. Similarly, any doors that lead to basements or crawl spaces should be air sealed.
Look for dirty spots on ceiling paint and carpet that indicate the presence of air leaks. These leaks can be a sign of mold and other problems. Seal these spots with caulk or low-expansion spray foam made for this purpose.
A common source of drafts under exterior doors is the threshold, where a gap forms between the floor and the bottom of the door. It’s important for the threshold to be even with the floor, which is why installers put shims under doors during construction. Mason suggests using a rolled-up blanket or foam sealant as a temporary solution to this problem, which he describes as “a cheap and effective alternative to buying a prefabricated threshold cover.” This is not a permanent fix, however, because evened floors can reduce air leakage, too. A more long-term solution is to install a threshold cover or cinch seam covers.
Ductwork
Ducts are the home’s circulatory system for distributing conditioned air throughout the house. But like any system, ducts can leak or be poorly sealed, which causes a waste of energy. Signs of leaky ductwork include a rise in your energy bill and certain areas of the house being warmer or cooler than others.
To locate air leaking from your ducts, turn on the furnace fan and feel for drafts. You’ll find that the leaks are often near where the ducts branch off or separate. To fix these leaks, apply foil duct tape over the hole or use mastic sealant over the gap. Mastic sealant is thicker and dries to form an airtight seal. It also cleans up easier than duct tape. When applying mastic, be sure to cover the entire surface of the leak and seam.
It’s important to inspect and repair ducts regularly, especially before the heating and cooling seasons. The more conditioned air that escapes into the attic or crawl space, the more it will cost to heat and cool the house. To keep costs down and ensure that your conditioned air is getting where it needs to go, inspect and clean your ducts each year and make any necessary repairs. If you have a problem that is beyond your ability to do on your own, contact an HVAC professional.