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Air Sealing

Air leaks are among the greatest sources of energy loss in a home. One of the quickest energy- and money-saving tasks you can do is caulk, seal, and weatherstrip all seams, cracks, and openings to the outside. By sealing uncontrolled air leaks, you can save 10%–20% on your heating and cooling bills. Following your energy audit, you may have a number of recommended energy-saving projects you are considering. Prioritize weatherization projects to quickly improve the efficiency and comfort of your home.

To identify air leaks, check around your walls, ceilings, windows, doors, lighting and plumbing fixtures, switches, and electrical outlets. Look for gaps, improperly applied caulk and weatherstripping, and doors and windows that don’t close tightly.

On a windy day, carefully hold a lit incense stick or a smoke pen next to your windows, doors, electrical boxes, plumbing fixtures, electrical outlets, ceiling fixtures, attic hatches, and other places where air may leak. If the smoke stream travels horizontally, you have located an air leak.

After you identify all air leaks, do the following:

  • Weatherstrip doors and windows.
  • Caulk and seal air leaks where plumbing, ducting, or electrical wiring comes through walls, floors, ceilings, and soffits over cabinets.
  • Install foam gaskets behind outlet and switch plates on walls.
  • Use foam sealant on larger gaps around window trims, baseboards, and other places where air may leak out.
  • Check for open replace dampers and make sure they properly close.
  • Consider an inflatable chimney balloon to seal your replace flue when not in use. Fireplace flues are made from metal, and repeated heating and cooling can cause the metal to warp or break over time, creating a channel for air loss. Inflatable chimney balloons are made from durable plastic and can be removed easily and reused hundreds of times. If you forget to remove the balloon before making a fire, the balloon will automatically deflate within seconds of coming into contact with heat.
  • Seal air leaks around replace chimneys, furnaces, and gas-fired water heater vents with re-resistant materials such as sheet metal or sheetrock and furnace cement caulk.
  • Install an insulated box to seal leaky attic stairs. Visit for DIY instructions.