GTA Winter Checklist for Windows, Glass and Doors

Do your winter prep for windows and doors in October and early November, before the first hard freeze. The list is short: find drafts and replace worn weatherstripping, caulk exterior gaps while it's still mild, check every double-pane window for fog between the panes, and clean and lubricate the hardware. Once the heat is on, keep indoor humidity in check so the glass doesn't stream with condensation.

Don't count on a late start. On 10 November 2025, about 10 cm of snow fell at Pearson, the earliest 5 cm-plus snowfall in more than 55 years. Then on 25 January 2026, Pearson recorded 46 cm in one day, its highest since records began in 1937, and January finished at 88.2 cm, the snowiest month on record there.

Why GTA winters are hard on glass and hardware#

The GTA isn't one climate. By heating degree-days, a standard measure of how much heating a location needs, the northern York Region towns are about 20% colder than downtown Toronto:

Deep cold is actually rare now: days below −20 °C have hovered around 2–3 a year in recent decades. The steady wear comes from cycling. Glass heats in the sun and contracts in the cold, and that daily movement works the edge seal of a sealed unit over years until humid air gets in.

The checklist at a glance#

1. Find drafts#

Air leakage accounts for 30–40% of a home's heating and cooling loss. Natural Resources Canada suggests checking window glazings for tightness, the window sash and casing, and around the door, including the threshold and the door frame.

On a windy day, move the back of your hand slowly around each closed sash and door, or watch the smoke from an incense stick. Note where it flickers. Check that the seal between glass and frame is intact, with no cracks or missing sections.

2. Replace worn weatherstripping#

Weatherstripping doesn't last forever, and the type decides how often you'll replace it:

On casement and awning windows, a draft along one side is often a hinge problem, not the weatherstrip. Hinges drift with house settling, temperature changes and wear, which shows up as uneven gaps, drafts and trouble locking. Adjust with the hinge screws, and replace hinges that are bent or stripped. Our guide to locks, hinges and weatherstripping goes into detail.

3. Caulk exterior gaps while it's still mild#

Sealants perform best between about 5 °C and 25 °C, so exterior caulking is a fall job, not a January one. Cut out cracked or shrunken caulk where the window frame meets the siding or brick, and re-seal.

One rule matters more than any other: don't caulk over weep holes. These small slots at the bottom of the frame let water drain out. When they're blocked, water pools against the sealed unit's edge seal and shortens its life. Clear them of dirt and spider webs while you're there.

4. Check every sealed unit for fog or cracks#

Walk the house on a cool morning and look at each double-pane window from a slight angle.

• Fog or droplets between the panes mean the seal has failed. The moisture can't be wiped away from either side and won't clear on its own. A failed seal also lets the gas fill escape, which can raise the unit's U-factor, its rate of heat loss, by up to 32%.
• A crack from the edge is likely thermal stress. See why windows crack.

Glass-only replacement keeps your frame. On site it takes about 20–30 minutes per opening, but units are made to measure, so allow 1.5–3 weeks from measuring. Booking in the fall means the new glass is in before the coldest weeks. For the tell-tale signs, see how to tell if a window seal is broken, or go straight to our foggy window repair service.

5. Clean tracks and lubricate hardware#

Grit and dry parts do most of the damage in winter, when hardware is stiff and people force it.

• Sliding windows: vacuum the tracks and apply silicone lubricant every six months.
• Casement cranks: lubricate twice a year with silicone or white lithium grease, and avoid petroleum oils, which attract dust. Operators fail from force more than age. The main culprit is cranking the window after it's already closed, which is tempting on a drafty night. If the handle spins freely, the operator is stripped and needs replacing.
• Patio doors: a healthy slider glides open with two fingers. Sand and grit in the track act as abrasives on the rollers. Vacuum the track before the snow, then keep it clear of ice melt and salt.
• Locks: if a key is stiff, use graphite lubricant rather than oil.

If a sash is frozen shut, let the room warm up rather than prying or cranking harder.

6. Set your humidity for the season#

Condensation on the inside of the glass is a humidity problem, not a window defect. Health Canada recommends keeping indoor humidity between 30% and 50%, and Natural Resources Canada adds: lower in winter, higher in summer. In practice, aim for 30–35% in winter, measured with a hygrometer.

Why lower in the cold? Classic National Research Council data from 1960 shows that at −18 °C outside, double glazing starts to condense at roughly 41–49% indoor humidity, and at −29 °C at about 32–39%. Modern windows do better than 1960 units, but the principle holds. A family of four also puts about 50 litres of water a week into the air. New, tighter windows can raise indoor humidity, too.

What helps: run bathroom and kitchen fans, vent appliances outside, open blinds and drapes so warm air reaches the glass, and use an HRV if you have one. Our condensation and humidity guide covers this in depth.

7. Reduce thermal stress on big panes#

Cold, sunny mornings crack glass. Keep blinds fully open or fully closed rather than half-drawn, and redirect floor registers and space heaters away from the glass.

8. Storm doors, screens and bedroom exit windows#

• Storm doors and storm windows: check that the closer works, the sweep touches the sill, and the glass or insert is intact. Toronto's property standards require exterior doors, windows, storm and screen doors and storm windows to be kept in good repair, free from defects and missing components, and weather-tight. That matters most for landlords.
• Bedroom windows: never screw, nail or caulk a bedroom window shut for winter. The Ontario Building Code requires bedroom egress windows to open from the inside without tools. If you seal the window with removable plastic film, make sure it can be torn away quickly.
• Basement window wells: keep them clear of snow. The code calls for 550 mm of clearance in front of an egress window in a window well, and a well full of snow blocks both the exit and the light.

9. Put together a broken-glass kit#

A window broken by a falling branch or a stray puck at −10 °C needs closing fast. Keep work gloves, a roll of heavy poly sheeting, strong tape and a broom and dustpan together. Our first-hour guide covers what to do. For anything large, on the ground floor or involving a patio door, call for an emergency board-up; our 24/7 line boards up the opening and the glass is replaced later in the same frame.

When to call a pro#

• Fog or a crack in any sealed unit, which needs a new unit.
• A crank that spins freely, a sash that won't close tight, or a hinge that's bent.
• A patio door that grinds, hops or needs more than two fingers to open after cleaning.
• Drafts that remain after new weatherstripping, which may mean the sash or frame is out of square.

What we'd do#

A fall visit from us looks like this list: we check each sealed unit for fog and cracks and replace any failed unit in its existing frame, and we adjust or replace hinges, cranks and rollers. If a frame is rotted or out of square, that's a window-replacement job, not a glass repair, and we'll tell you if that's where you are.

Next step#

Fogged or cracked glass gets a new sealed unit in the frame you have, and worn hardware gets new parts. See our window and door hardware repairs or send photos of the problem windows through our contact page for a free quote before the cold sets in.