The first step to reduce drafts is to identify the air leakage areas throughout your home. Although you might feel drafts and see air leakage areas around windows and doors on the main floor, in most homes, the most significant air leaks are often found in the attic/top floor and basement/lowest floor and are often hidden. This is due to the stack effect: In a heated home, less dense warm air rises and expands, creating a higher-pressure area near the top of the house. As cold air pushes into the lower portions of your home it forces the lighter warm air up and out through leaks at the top.
In general, the priorities for air sealing are:
- Large holes regardless of location (plumbing or electrical penetrations, ductwork through unconditioned spaces, large gaps under doors, masonry chimney chaseways).
- Smaller holes on top floor ceiling/attic (pot lights, ceiling penetrations around fixtures, attic hatch, attic knee walls, service shafts, etc.).
- Smaller holes on the bottom floor (hose bib penetrations, cracks on exterior and foundation walls, basement doors, electrical boxes, gas lines or oil fill pipes that go through exterior walls, etc.).
- Smaller holes at main floors (windows, doors, top and bottom of baseboards, fireplace dampers, electrical outlets, switches).
Various materials throughout the envelope act as an air barrier. Large-surface building materials such as drywall, baseboards or structural members and windows and doorframes are incorporated into the air barrier by sealing them to the adjoining materials. Caulking, tapes and gaskets are used for joints between materials that do not move, and weatherstripping, for joints that do move.
When choosing draftproofing materials always select premium products for long-term durability. Choosing the proper product and paying attention to the quality of application are crucial.
Materials you may want to use for draftproofing include:
- Caulking is used to seal joints between building components.
- Weatherstripping is used to block air leakage around doors and the operable parts of windows.
- Spray-foam insulation is a plastic resin used to insulate, but also acts as an air barrier.
- Most solid building components including drywall, plaster, plywood, glass, wood, rigid foam insulation and poured concrete (not concrete blocks) will act as air barriers.
- House wrap, polyethylene sheeting, and polyamide sheeting typically act as air, vapour, or combination barriers, respectively.
For detailed information on draftproofing materials, see the Natural Resources Canada resource Keeping the Heat In. Additional guidance is available from BC Housing’s Best Practice Guide Air Sealing and Insulation Retrofits for Single Family Homes.
For a more in depth air sealing analysis of your home, you can have an EnerGuide home evaluation performed on your home to find any obvious or hidden drafts that need sealing. A program-qualified energy advisor will conduct a site visit, perform a blower door fan/depressurization test and look for air leaks. The advisor will also use the data from the depressurization test and calculate the air leakage rate for your home. In the Renovation Upgrade Report, the energy advisor will give a prioritized list of draftproofing measures for your home.
Did you see a building science or energy efficiency term you did not understand? Check out our glossary.