Building envelope: Air sealing

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Save up to 30% on energy costs

Diagram of house showing common areas of air-leaks

Keeping in the heat

The single most important thing you can do to improve the energy efficiency of your home

Air sealing is one of the most affordable and easy ways to improve the energy efficiency of a home. It's the single most important thing you can do to improve the energy efficiency and should be the first step of any retrofit project. You can save up to 30% of your energy costs by air sealing areas where energy loss occurs.

Air sealing impacts the building envelop of your home. The building envelop is the physical separator between the conditioned and unconditioned environment, including the resistance to air, water, heat, light, and noise transfer. Older homes typically have more air leaks, around windows and doors, electrical outlets, and cracks in the foundation and walls. You can seal air leaks in your home with weather-stripping and caulking or by applying gaskets and tapes.

What to look for

  • Detect all sources of air leakage before you undertake your project; assess your ventilation needs to ensure adequate indoor air quality.
  • Each house will respond to air sealing in its own way, so monitoring is important. Older homes may require remedial measures – such as mould or asbestos removal before comprehensive air sealing.
  • Every time you insulate, install or upgrade the air barrier system, it’s important to ensure that moisture does not enter the insulation or building envelope.
  • Types of air sealing products include:
    • Caulking, a putty-like substance best applied to non-moveable gaps like baseboards and wood trim
    • Weather-stripping tapes and plastic forms
    • Expandable spray foam which can be applied to irregular-shaped air gaps
    • Shrink-wrap plastics which can be applied to the interior of windows
  • For detailed advice on air-sealing contract a professional installer.

Things to consider

  • Be sure to check window glazing, thresholds and door/window frames and electrical outlets and switches as potential sources of air leakage.
  • Choose premium caulks for durability. Practice running and smoothing beads before you do the actual job.
  • Check the size and colour of doors and windows before purchasing weather-stripping to ensure you buy the right product. Adhesive-backed foams and tapes can lose their effectiveness over time so you may need to replace it every few years.

Avergage cost

$200 – $1,500

Source: Natural Resources Canada

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