Fall Checklist: 10 Things to Do Before the Heating Season

In Quebec, the heating season starts in earnest around mid-October and does not really let go until April. Everything your windows and doors will do wrong this winter — drafts, frost on the glass, a lock that will not turn at -25 °C — is already set up in September. This ten-point routine takes an afternoon and is specific to windows and doors: no gutters, no furnace filters, just the openings in your walls that decide how comfortable and how expensive your winter will be.

Why September Is the Deadline, Not November

Most homeowners think about windows the first morning they wake up to frost on the inside of the glass. By then, the outdoor temperature has dropped below the point where sealants cure properly, foam insulation stops expanding correctly, and installers' calendars are full through the holidays. Montreal typically sees its first frost between the last days of September and mid-October, and the Laurentians and Quebec City run one to three weeks earlier.

Fall work is also easier work. Weatherstripping is pliable at 15 °C and brittle at -10 °C. Weep holes clear with a toothpick when the debris is dry, and turn into ice plugs once meltwater has nowhere to go. A lock that turns stiffly in October will seize in January, when the grease inside has thickened and the frame has contracted a millimetre or two around the bolt.

The routine below is ordered roughly from quickest to most involved. Points one through seven are inspection and light maintenance; eight and nine set you up to read your windows correctly all winter; ten is the one that actually has a calendar attached to it.

1. Test Every Lock and Check Seal Compression

Start with the operating hardware, because it tells you about everything else. Open and close every casement, awning, slider and door, and work each lock through its full travel. A casement lock that needs the sash pulled in by hand before it will engage is telling you the sash has dropped or the frame has racked — both of which get worse in cold weather as the vinyl or wood contracts.

Then check compression. Close the window, slide a strip of ordinary paper between the sash and the frame, and lock it. If the paper pulls out with no resistance, the weatherstrip is not being compressed at that point and cold air will find the gap. Test at all four corners and mid-span on each side; casement windows usually fail first at the corner opposite the hinges, doors at the top latch-side corner.

On a multi-point lock (most casements built after 2005 and most quality entry doors), all the keepers should engage at once with one motion of the handle. If one keeper catches early and the rest do not, the sash is slightly out of square. Many keepers have an eccentric cam adjustment that takes a hex key and thirty seconds; if yours do not, a service call is worth booking now rather than in January.

2 and 4. Clear the Weep Holes, Then Clean the Sills

Every window with an exterior sill track — sliders, single-hung and most casements — has small slots along the outside bottom of the frame. These weep holes let rain and condensation drain out instead of pooling against the glazing seal. Over a summer they fill with pollen, cottonwood fluff, spider webs and roofing grit. Blocked weep holes are the single most common reason a perfectly good window shows water on the inside sill in November.

Clear them from the outside with a plastic zip tie or a pipe cleaner — never a metal screwdriver, which chips the vinyl and creates a permanent snag point. Pour a cup of water into the sill track from inside and watch it drain out; if it does not, the internal channel is blocked and needs a shot of compressed air from the interior side. Do this before the first freeze, because an ice plug in a weep channel will not clear until April.

While you are there, clean the sills. Vacuum the track of a slider until it is bare, then wipe it with a damp cloth and mild detergent. Check the exterior sill for cracks in the caulking where it meets the siding or brick: a hairline crack in September becomes a channel for meltwater and ice, and frost heave will widen it. This is a look-and-note task; recaulking itself belongs on a dry day above 5 °C, and most sealants specify that on the tube.

3 and 5. Screens Off and Stored, Hardware Lubricated

Removing your screens for winter is not fussiness. A screen left in a casement window holds snow and ice against the sash, keeps sunlight off the glass, and traps condensation between mesh and glazing. On sliders, an iced-up screen stops the sash from reaching full closure and the lock from catching. Manufacturers design screens to come out in seconds precisely because they expect them to be removed for five months of the year.

Wash each screen with a soft brush and soapy water, let it dry fully, and label it with masking tape — living room left, kitchen over sink — before storing it flat or upright in a dry spot. Never stack screens on their mesh, and never store them where a car door or a snowblower can catch a corner; replacing a bent aluminum screen frame costs more than the screen is worth.

With the screens out, you have clear access to the hardware. Lubricate hinges, casement operators, roller tracks and lock mechanisms with a dry silicone spray or a PTFE lubricant — not WD-40, which is a solvent that washes grease out and attracts grit, and not general-purpose oil, which thickens at -20 °C. Work each mechanism ten times after spraying. A single can does the whole house and the difference in January is obvious.

6 and 7. Thresholds, Door Bottoms and a Glass Check

Exterior doors have their own vulnerability at the bottom. On most modern entry doors, the threshold has an adjustable cap held by four or five screws; over a summer of foot traffic and wood movement, it can drop a millimetre and open a gap under the door sweep. Close the door, get down on the floor with a flashlight on the other side, and look for light along the bottom edge. Raise the threshold cap a quarter-turn at a time until the light disappears without the door dragging.

Patio doors deserve the same check at the interlock — the vertical edge where the sliding panel meets the fixed one — and at the bottom track, which should be free of grit and have a continuous, uncrushed weatherstrip. Look at the exterior threshold for standing water after a rain: a threshold that ponds will ice over, and an iced threshold is a slip hazard and a door that will not seat.

Then walk the house and look at every pane. You are looking for three things: a faint haze or streaks between the panes that will not wipe off either side, which means the sealed unit has lost its gas fill and its seal; any crack, even hairline, especially at the corners; and glazing beads or exterior glazing tape that has pulled away from the glass. A failed sealed unit will not get worse in a dangerous way, but it has lost most of its insulating value and will condense heavily this winter. Replacing an insulated glass unit is priced by size and coating; a cracked pane should be scheduled immediately, before cold contracts it further.

8 and 9. Set a Condensation Baseline and Your Winter Humidity Target

Condensation on interior glass is the most misread window symptom in Quebec. It is usually not a window defect; it is a sign that the indoor air holds more moisture than the coldest surface in the room can carry. But you cannot tell a normal amount from an abnormal one unless you know what your windows do in mild weather. So in late September, on the first morning around 5 °C outside, note which windows show any moisture at the bottom edge of the glass and how wide the band is. That is your baseline.

Then set your humidity target. The guidance used by CMHC and most Quebec HVAC contractors ties indoor relative humidity to outdoor temperature: around 40% at 0 °C outside, 35% at -10 °C, 30% at -20 °C, and 25% or lower during -30 °C cold snaps. An inexpensive hygrometer on the main floor and one in the bedroom are enough to manage this. If your home has a central humidifier, find its setpoint now and plan to lower it in steps through December.

Windows with double glazing and standard aluminum spacers will show a band of moisture along the bottom edge once outdoor temperatures drop below about -15 °C at 35% indoor humidity. Triple-glazed units with warm-edge spacers push that threshold to roughly -25 °C or below. Knowing which glass you have tells you whether the condensation you see in January is your air or your window — and in the second case, whether it is time to look at replacement windows with better spacers and a third pane.

10. Book Replacements Before the Ground Freezes

If any window failed the paper test on more than one side, has a fogged sealed unit, or has a frame that has visibly bowed or cracked, the honest answer is replacement, and the timing matters. Manufacturing lead times for custom windows in Quebec run six to ten weeks in a normal season and stretch in the fall. An order placed in mid-September installs in November; an order placed in late October is a January installation.

Winter installation is entirely possible — good crews do it all season with one opening at a time and temporary closure — but fall installation is simply better. Low-expansion foam and exterior sealants have specified application temperatures, usually 5 °C and above, and cure properly. Brick mould and exterior trim can be painted or caulked the same week. You are not heating the outdoors for the two hours the opening is exposed.

Prioritize by exposure. The north and northwest faces of a Quebec home take the prevailing winter wind; a leaky window there costs more in heating and comfort than the same window on the south side. Replace in order of draft severity and orientation, not room by room, if the budget only covers a few this year. The installed price of a quality UPVC casement depends on size and glazing; the return on the worst windows in a house is measured in a few winters, not decades.

The Full Checklist

Here is the whole routine in one place. Print it, tape it inside the utility closet, and work through it on a dry weekend before Thanksgiving. Most homes need about three hours for points one through nine; point ten is a phone call.

• 1. Locks and compression: work every lock; paper test at corners and mid-span.
• 2. Weep holes: clear with a plastic zip tie; confirm drainage with a cup of water.
• 3. Screens: remove, wash, label, store flat and dry.
• 4. Sills and tracks: vacuum tracks; note any cracked exterior caulking.
• 5. Hardware: dry silicone or PTFE on hinges, operators, tracks and locks.
• 6. Door thresholds: flashlight test under the door; adjust the threshold cap; check the sweep.
• 7. Glass: look for fog between panes, cracks and loose glazing beads.
• 8. Condensation baseline: note which windows show moisture in mild weather.
• 9. Humidity: install hygrometers; target 30% at -20 °C; step the humidifier down.
• 10. Replacements: order by mid-September for a fall install; prioritize north and northwest faces.

Frequently Asked Questions