As much as 30% of home energy costs are wasted due to air leaks. Having a “leaky” home causes an exchange of warm and cool air through openings in the building. Air sealing creates a barrier at openings to prevent or minimize air movement, saving energy and increasing comfort. Even if you’re living in a new building, having a well-insulated home does not mean your home is adequately sealed. Homeowners can correct minor problems with air leakage in the following ways:
1. Look under sinks on exterior walls to see if waste or water pipes are going through holes in the wall much larger than the pipe. If so, use spray foam insulation to seal these spaces.
2. Windows and doors are a big source of energy loss, but this is compounded by little or no insulation between gaps in the framing. Remove moldings and fill gaps in the frame using spray foam insulation designed specifically for doors and windows, which will not warp framing as it expands. After replacing trim, caulk around door and window frames using an acrylic-latex caulk, preferably one that’s paintable. Don’t worry if you aren’t a pro at beading a straight line of caulk — use non-glossy clear caulking that won’t showcase mistakes, or buy an inexpensive caulking tool to create a neat profile and minimize stretching and cracking. If necessary, install new weatherstripping.
3. Check for basement cracks along floors or basement walls, as well as gaps along the sill plate and foundation and at the top and bottom of rim joists. (Rim joists are located at the ends of the building, the final joist that supports the floor/ceiling.) For cracks less than ¼” wide, use acrylic latex caulk to seal. For larger gaps, use spray foam insulation according to manufacturer’s instructions.
4. Insulate outlets and switches on interior and exterior walls by removing receptacle plates and applying foam sealers to eliminate the flow of air. If there are unsealed gaps around the outlet boxes, use spray foam insulation to fill open areas (do not spray the interior of the box).
Other areas of the home require more in-depth investigation to determine whether they have been properly sealed. It’s safer to hire a professional weatherization contractor if you have the following conditions: Recessed lighting (these must be sealed in a specialized manner to prevent a fire hazard), vents exhausting into attic spaces, mold – especially in basements or attics, wet or excessively damp conditions in either the attic or basement, or old wiring.
5. Check attic insulation for dirt; check exterior for ice dams. Attics and basements are the largest source of air leaks due to “chimney effect.” Chimney effect happens when cool air is drawn in through the basement and hot air generated by the furnace rises up and into the attic. Pressure is created at the highest and lowest points causing a drafty home. If there is batt insulation in your home, and a weatherization specialist sees dirt on the insulation, that’s a sure sign of air movement. Finished attics are not immune to air leaks, which can occur in openings in sidewalls and kneewalls. Note: Extra precautions must be taken in older homes with vermiculite insulation (gray, pea-sized granules) that may contain asbestos, so it’s important for homeowners not to disturb any insulation and consult with a professional first before making their own assessment.
Another costly and serious symptom of poor air sealing is ice dams. Ice dams form when there is a temperature difference between the higher parts of the roof and the eaves. During the winter, snow melts on the upper portion of the roof and flows down to the edges of the roof, re-freezing as temperatures drop, especially at night. This forms a build-up of ice as the thaw-freeze cycle repeats itself. Eliminating the flow of warm air into the attic space is the only permanent solution. Left uncorrected, ice dams will damage a roof and eventually cause water leaks into the home.
6. Seal supply ducts. They are one of the greatest sources of energy loss as well, mainly due to significant temperature differences between the leaky supply air and the indoor environment, impacting heating and cooling efficiency.
Typically, a weatherization specialist will complete a whole-house assessment to locate sources of air leakage, evaluate problem areas and make specific recommendations to help you lower your monthly bills. There are several incentives available to homeowners who increase the energy performance of their home. The Database of State Incentives for Renewables & Efficiency (DSIRE) can provide state, local, utility and federal incentives on their website and is funded by The Department of Energy. For more information: http://www.dsireusa.org.
Assistance is available to low-income families who wish to increase their home energy efficiency through the Weatherization Assistance Program (WAP), also funded by The Department of Energy and implemented through community action programs and other local non-profit agencies. For more information: http://energy.gov/eere/wipo/weatherization-and-intergovernmental-programs-office.