Draft-proofing tips

You will need:

  • Access to basement

  • A ladder

  • Flashlight

  • Incense sticks

  • A piece of paper

What are you looking for?

  • Light from the outside coming through joints in the wall.

  • In cold weather feel for drafts.

  • If uncertain of where drafts are originating, slowly move a lit incense stick around the edges of all windows and doors; if the smoke drifts to the side, it indicates an air leak that needs to be sealed.

  • Any area where pipes, wires, vents, etc. are entering/leaving the house, check for light, cold air coming in or use incense stick assess where the leak is. 


  • Check for any cracks that allow daylight to enter your basement, especially around foundation lines.

  • Thoroughly check around all windows and doors. Leaks can occur around the casing or within the window or door unit itself.

  • Check for any cracks where the floor and wall meet and where the ceiling and wall meet.

  • Look around all pipes and vents where they go through any wall or up to another room in the house through the ceiling. If there is a gap between the pipe or vent and the surface they go through, the opening needs to be sealed.

Kitchens, Bathrooms, Bedrooms, and Living Areas

  • Thoroughly check around the framing for all windows and doors.

  • To ensure windows and doors are closing tightly: place a piece of paper on your window sill or under the door, and then close the window or door on the piece of paper. Once closed, try to pull the piece of paper out. If it easily slides out without folding or tearing, there is a big enough air leak that you should install a new threshold and or weather stripping.

  • For rooms with sinks: Under the sink, check to see if there is a gap around the pipe where it goes through the wall. If there is a space, it needs to be sealed up.

  • Check for air leaks along baseboards where the board meets the wall and the floor.

  • Air leaks can also occur where a hole has been cut in the wall or ceiling to install a switch, outlet, or a light. After removing covers, look for any locations where there is a large gap between the surface and the electrical box, This gap should be filled. If you are sealing around outlets or light switches be sure to turn off the power during application and dry time of your product.

Outside your home

  • Check around all windows and doors for gaps and cracks where two surfaces meet. These joints are easily sealed with caulks and foam sealants. Use flexible, exterior caulking.

  • Look for gaps around pipes and vents and seal any holes or gaps with a caulk or foam sealant, again making sure that your product selection can be used for exterior applications.

  • If your home has wooden or vinyl slat siding, check for gaps along the corner board (the vertical board that covers where the ends of the siding meet on the corner of your home).

  • Check along the foundation line of your house for cracks that can be sealed.

NOTE : External caulking should focus on reducing moisture entering the home. Most siding is designed to vent thus sealing it will not stop drafts. For more information see:http://joneakes.com/cgi-bin/getdetailscals.cgi?id=2043

Additional tips

  • To check for leaks around doors and windows,

  • Mark all the leaks you find using painters tape or sticky notes. Then go back and seal.

  • In addition to the locations outlined above, while inspecting your home, look for areas where two unlike materials join together. This indicates that there is a break in surfaces where air can easily travel through if not properly sealed.

  • Air leaks are more easily felt in the winter, with a "draft" of cold air leaking into the house.

  • If you have a fireplace or woodstove, make sure the damper is tightly closed when not in use as this can be a source of major air transfer. Other options include installing glass fireplace doors that close snug, or installing a chimney balloon.

  • If you have an unused chimney, be certain to seal it with a chimney cap.

  • Seal your attic hatch with foam weather stripping.

Choosing the Right Product

  • Gaps and cracks: When sealing smaller air leaks here is an easy guide for the products to use:

      • Gaps up to 1/2": Caulk

      • Gaps up to 2": Latex foam sealant

      • Gaps over 2": Polyurethane foam sealant

  • Windows: You can quickly seal around windows using caulks and weather-strip tape. You can also apply window film in the winter. If considering replacing your windows, ensure your selection is Energy Star certified.

  • Doors: As with windows, sealing around doors is quick and easy. Use caulks and weather-stripping to seal the perimeter of the door, and install a threshold to prevent air from leaking from under the door.

  • Baseboards: In older homes, it may be useful to take of quarter round and fill the gap behind with backer rod. If the draft is small, use clear caulk to seal the cracks between the floor and baseboard and the top of the quarter round and the baseboard.

This document was based on http://www.sealyourhome.info/projectpages/FindAirLeaks.aspx, edited for Green Together Draft Proofing workshop January 21, 2009.

Green Together is a Project of Green Neighbours 21, supported by grants from the Trillium Foundation and the Ontario Government through their Community Go Green program.