Air leaks in the house cost money and cause comfort problems. Sealing leaks saves energy and reduces drafts.
This article shows how to identify and seal leaks with inexpensive materials. You can find these items at any full-service hardware store or home center.
Windows and Doors
Air leaks around windows can lead to cold drafts in the winter and high energy bills. The problem is caused by faulty seals, which can be easily fixed with caulk or weather strip. Window leaks also occur when frames shift and expand with changes in temperature or humidity. In addition, older window frames can develop mold, mildew and rot, which isn’t ideal for the structure of your home.
One way to find air leaks in your windows is to use a smoke test. With your HVAC system turned off, hold a lit candle or incense stick close to your window seals and watch how the smoke moves. If the flame flickers or moves in a particular direction, it indicates that there is an air leak and where it is located.
In addition, using plastic window wraps can help minimize drafts and reduce energy costs. These are inexpensive and can be purchased from most hardware stores. Another option is to install interior storm windows that are custom-made for your home. These provide a much better insulating value than traditional double and triple pane windows. They are also very attractive and can be used in combination with heavy drapes or curtains to keep warm air inside your home during the winter. If you are considering replacing your windows, contact a reputable company to ensure the best quality and installation of your new windows.
Attic
An attic is a notorious source of air leaks in a house, especially when poorly insulated. But insulating an attic properly is not as simple as caulking around doors and windows. It involves a lot of moving and shifting insulation, and attic spaces are often tight and difficult to access. It is a good idea to wear a dust mask when doing this work to reduce the risk of breathing airborne toxins.
When examining your attic space, look for areas where ceiling height changes, such as dropped soffits over kitchen cabinets or bath vanities and slanted ceilings over stairways (Photos 1 – 3). These areas are major sources of leaks because they often have open stud cavities leading into the attic from the living spaces below. Make a sketch of your attic floor plan and locate the main plumbing stack, flue or chimney, as well as any other penetrations that you want to seal.
You can seal most large gaps with caulk or expandable foam spray, but to ensure that the leaks are completely sealed, use a garbage bag plug. This is a cheap and effective method for sealing these areas. It is also a good idea to fill any empty gaps with a combination of foam, fiberglass and cellulose insulation, as this will provide the most protection against air leaks from the attic to the living space below.
Basement
Basements are a major source of air leakage in many homes. They can also be a source of moisture problems and mold, which in turn can cause damage to the house frame and insulation. A qualified contractor should be used to inspect and air seal the basement.
The main entry paths for air into the basement are at the sill plate and rim joist where the wood framing of the house sits on the concrete foundation or cinder block wall. These areas can be sealed with caulk or spray foam. Holes that go through the rim joist and the foundation for wiring, pipes, vents, and hose bibs should be sealed with caulk or rigid foam board, as well.
In some houses, basement ducts can draw air from unconditioned spaces such as the attic and crawlspace into the return air ducts, which in turn can leak warm air into the basement. This is usually not a problem if the basement ducts are properly sized and insulated.
Once you have sealed the leaks in windows and doors, and in the attic, it is time to move on to other areas of your house. Using the blower door test, or smoke sticks or incense to locate leaks, you can then apply caulk, spray foam, and weather stripping to seal these areas. If your home has a chimney or gas appliances, it is important to arrange for combustion-safety testing after the air sealing work is completed.
Other Areas
Almost every house has a lot of hidden air leaks that rob it of energy. Sealing them is one of the most cost-effective ways to improve comfort, reduce energy bills and protect your home from moisture movement that contributes to mold and rot.
A building performance professional can use a blower door test to pinpoint where air is moving erratically and help you make a plan for sealing these areas. You can also test for air leaks on your own using a visual inspection. Hold up a lit incense stick or piece of paper near the suspected leaks; if the smoke or paper moves erratically, unwanted air is entering or exiting the home in that area.
Another option is to have one person stand outside and shine a bright flashlight toward the inside of the home; any areas that are glowing are areas where air leaks are occurring. Be sure to wear a dust mask or respirator when performing any type of insulating work in the attic or basement. The dust created can be harmful if inhaled.