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Detecting and Sealing Air Leaks Around the House


New homes are built tightly to ensure heating and cooling efficiency, but if your home is older than a decade or two, hidden leaks might be wasting money every month. Many homes could have 10 to 30 percent lower utility bills if their owners took the time to find and seal air leaks. Here’s how to determine where your home is leaking and how to seal all the cracks, seams, and openings that waste heated and cooled air.

Test for Air-Tightness

Before you can seal any air leaks, you must know where they are. The most common areas that leak air include:

  • Windows and doors
  • Electrical outlets and switch plates
  • Plumbing fixtures
  • Ductwork
  • Wall- or window-mounted air conditioners
  • Attic hatches
  • Mail slots
  • Doggie doors
  • Ceiling lights and vents
  • Dropped soffits
  • Baseboards
  • Dryer vents
  • Sill plates and top plates

Here are a few techniques for detecting air leaks:

  • Visual inspection: Look for gaps or cracks in the places listed above. Test if you can rattle windows and doors, a sure sign of air leaks. You can also shine a flashlight around windows and doors at night to see if the person inside can see the light through the frame.
  • Home depressurization test: Wait for a windy day to perform this test. First, turn off the HVAC system and shut all the windows and doors. Then, turn on the exhaust fans in the kitchen, bathrooms, and laundry room. Light an incense stick or smoke pen and hold it near common leaky areas. If the smoke wavers, you have found a leaky area that needs to be addressed.

Seal Air Leaks

Different leaks require different sealing methods. For instance:

  • Caulk stationary joints around windows and doors.
  • Replace old weatherstripping in moveable joints of windows and doors.
  • Apply caulk anywhere plumbing, ductwork, and electrical wiring enter your home through the floor, wall, ceiling, or soffit.
  • Install foam gaskets behind light switches and outlets positioned on exterior walls.
  • Inspect attic insulation for dirty spots, which indicate leaks through the attic floor. Seal the leaks you find with expanding spray foam.
  • Replace single-pane windows with efficient double-pane windows. If the upgrade is outside your budget, install storm windows over the existing glass during the winter.
  • Install foam sealant in significant gaps around baseboards, windows, and other leaky areas.
  • Install pliable, sealing gaskets on the bottoms of exterior doors to create an air-tight seal when the door is shut.
  • Close the fireplace damper when not in use.
  • Seal air leaks in and around the chimney, furnace, and water heater vents with sheet metal, sheetrock, furnace cement caulk, or another approved fire-resistant material.

With your home all sealed up, your utility bills should drop noticeably. Want to learn more ways to decrease energy consumption in your Berkeley, CA home? If so, contact Albert Nahman Services at (510) 876-9725 for reliable heating and cooling tips.

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