What it usually means, the likely causes in order, what to safely try first, what a pro charges in Canada, and when to stop and call one.
This guide covers the common cases. Describe your exact problem and get a personalized diagnosis — free to start, with a DIY vs. call-a-pro verdict and a real cost estimate.
A window or door that lets in cold or hot air is almost always a sealing story rather than a glass story: worn or missing weatherstripping around the frame, a sash or door that no longer closes tightly against its seals, or gaps where the frame meets the wall. The moving parts of a window or door compress their seals thousands of times, in sun and frost, until the material flattens, cracks, or peels away entirely. The result is felt more than seen: a cold line along one edge in winter, a room that never matches the thermostat, and heating or cooling quietly leaking outdoors through a gap you could cover with a finger.
A draft is a comfort and energy problem, not an emergency, and it does not usually worsen quickly. It is worth fixing before the coldest or hottest part of the year rather than after a season of paying to heat the outdoors. Move faster if the draft comes with water entry during rain, if you can see daylight around a closed exterior door, or if a door is so loose it rattles in its frame, because those point to a fit problem beyond a tired seal and can affect security and weather protection as well.
The most common cause. Foam, rubber, and felt seals compress permanently with age, crack in sun and cold, and adhesive-backed types peel away from corners. Because the seal fails gradually, homeowners often blame the window itself when a close look shows the glass and frame are fine and only the soft strip between them has given up.
Hinges sag, latches wear, and lock hardware loosens until the door or sash sits a fraction short of fully closed, leaving one edge uncompressed and drafty while the latch side feels tight. A draft concentrated along the top or the hinge side, with a door that needs lifting or slamming, points here rather than at the seal material.
The joint where the window or door frame meets the surrounding wall is sealed with caulk outside and trim inside, and both fail with age and building movement. A draft that seems to come from behind the trim, rather than between sash and frame, is this gap breathing, and no amount of weatherstripping on the sash will fix it.
Wooden doors and frames can warp or shrink with humidity change and age, opening a seasonal gap that appears each winter when indoor air is driest. A draft that follows the calendar, worst in deep winter and gone in summer, is usually shrinkage and fit, which shapes whether the fix is a seal, a fit adjustment, or accepting a seasonal product.
| Job size | Typical estimate (CAD) |
|---|---|
| Simple fix — the straightforward version of this repair | $100–$300 |
| Major job — complex, hidden, or replacement-level work | $300–$900 |
Estimates only, calibrated to Greater Toronto Area trade rates and adjusted by region on this site — not a quote. Your exact price depends on the cause, parts, and access. A personalized diagnosis narrows this range using your specific symptom.
Weatherstripping, door sweeps, and foam tape are among the best-value DIY jobs in a home: inexpensive, reversible, and immediately felt. Call a pro when the draft survives new seals because the door or sash itself is misaligned or warped, when the gap is between frame and wall and involves exterior work at height, or when several units need hardware and fit correction. A pro can also tell you honestly if a window is so far gone that sealing is money spent delaying a replacement, rather than selling you seals for a unit that cannot close straight.
Use a windy day and a slow hand pass around every edge of the closed unit, or hold a lit candle or incense stick near the frame and watch for flickering or smoke being pulled. Work methodically around all four sides and the meeting rail of double windows. Mark the spots you find, because drafts often come from one failed section, and replacing or sealing only that section is faster and cheaper than treating the whole unit blindly.
When worn seals are the cause, yes, usually immediately: the cold line at the edge of the door disappears and the room holds its temperature more evenly. Weatherstripping is inexpensive enough that it is the right first step almost regardless. If a draft is unchanged after sound new seals and a verified full close, the gap is elsewhere, most likely frame-to-wall or a warped unit, and further seal products will not solve it.
Wind creates pressure differences across the building, pushing air in on the windward side and pulling it out on the sheltered side, so the same gap leaks far more air under wind pressure than on a calm day. That pattern is actually reassuring diagnostically: it confirms you are chasing an air gap, not a cold material or an insulation problem, and it tells you which exposure to check first.
The door sweep and the threshold. The sweep is the finned or brush strip attached to the bottom of the door, and it wears faster than any other seal because it drags on every close. Look for daylight, feel for the air line, and check whether the threshold itself has dropped or its own seal has flattened. Replacing a sweep is a short job with basic tools, and it often removes the single biggest draft in the house.
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