Hoe do I stop drafts coming through my windows?

Drafts coming through windows are one of the most common complaints from Ottawa homeowners, especially during our brutal winters. The good news is that many draft sources can be identified and addressed without replacing the entire window.

Start by finding the source of the draft. On a cold, windy day, hold your hand around the window frame, sash, and where the window meets the wall. You can also use a lit incense stick — the smoke will visibly shift near air leaks. Common culprits are worn weatherstripping, dried-out caulking around the exterior frame, and gaps between the window frame and the rough opening in the wall.

Weatherstripping is the easiest fix. The foam, rubber, or vinyl strips that seal the sash against the frame wear out over time, especially in Ottawa's freeze-thaw cycles. Replacement weatherstripping is inexpensive and available at any hardware store. Press the new strip firmly into the channel around the sash and check that the window closes snugly against it.

Caulking the exterior perimeter is the next step. If the caulk bead where the window frame meets the exterior siding is cracked or missing, cold air will work its way in. Scrape out the old caulk, clean the surface, and apply a fresh bead of paintable or silicone exterior caulk rated for Canadian winters. Do the same on the interior side where the window trim meets the drywall.

When drafts persist despite fresh weatherstripping and caulking, the window itself may be the problem. Older single-pane or failed double-pane windows lose their seal, and no amount of weatherstripping will compensate for glass that's simply not insulating. In Ottawa's Climate Zone 6, an ENERGY STAR-certified triple-pane window with a U-factor of 1.22 or lower makes a dramatic difference in both comfort and heating bills.

If you've done the basic sealing and still feel cold air, it's worth having an experienced installer assess whether the window frame has shifted, whether the insulation in the rough opening has degraded, or whether replacement is the more cost-effective path. The contractors we match you with can identify the root cause quickly and give you an honest recommendation.

For a free, no-obligation quote on window replacement or to get a professional assessment of your drafts, submit your details through Ottawa Window Pros and get matched with local contractors from the Ottawa Construction Network.

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