Find the leaks with an incense stick, caulk the fixed joints, weatherstrip the moving parts, and do it above 5°C. On a house built before 1960, treat the old paint as lead paint until it's tested.
An older home in King City is a different job from a suburban house. The windows may be original wood sash with decades of paint on them, the heat may be propane, oil or a wood stove, and there may be no neighbour's wall to shelter the weather side. Here is what actually matters when you reseal windows and doors before winter, and what to check before you start scraping.
Find the leaks before buying anything
Pick a cool, breezy day. Close the windows and doors, then hold a stick of incense or a strip of tissue near the frame edges, the sill, the corners and the gap under each door. Wherever the smoke bends or the tissue flutters, air is getting through. A Saskatoon air-sealing fact sheet, which credits Natural Resources Canada for its leak diagram, says air leakage can account for 25 to 40 percent of a home's heating and cooling energy. That is a general figure, not a promise about your house, but it is why this is worth an afternoon.
Caulk the fixed joints, weatherstrip the moving ones
The rule of thumb from the U.S. Department of Energy is simple: caulk is for joints that don't move, such as where the window or door frame meets the siding, brick or trim. Weatherstripping is for parts that do move, such as the edges of a door and the sash of a window that opens.
- Remove the old compound first. Hydro-Québec says to cut out split, dried caulk with a utility knife and brush the joint clean. New caulk over crumbled old caulk fails early.
- Mind the gap size. For cracks wider than about 6 mm (1/4 inch), Hydro-Québec says to push in foam rope or a foam backer rod first, then caulk over it. Caulk alone in a wide gap shrinks and splits.
- Match the caulk to the surface. Use a flexible, good-quality exterior caulk, paintable where it will be painted. Read the cartridge for the surfaces and temperatures it allows.
- Check the sweep and threshold. A worn door sweep or a gap at the bottom of an old farmhouse door often leaks more than the frame does.
Why timing matters on an old rural home
Hydro-Québec's guidance is not to caulk where the temperature is below 5°C, because the compound stiffens and won't seat properly, and dry weather is preferred. In King Township that gives you a limited window in October and early November. If the forecast is turning, do the exterior caulking first and the interior weatherstripping afterwards, since interior work isn't tied to the weather.
The lead paint question
Health Canada says a home built before 1960 probably contains lead-based paint, and one built between 1960 and 1990 may have it on the exterior. Windows and doors are named as places where normal wear disturbs it. Health Canada's advice for doing the work yourself includes not using sanders, heat guns or blowlamps on the paint, keeping children and pregnant women away, wearing goggles, gloves and a good-quality breathing mask, and sealing scrapings in a container labelled hazardous waste. Intact paint left alone can be safer than removing it. You can send a paint chip to a lab, or hire someone with X-ray equipment to test it.
In practice, that means a quick re-caulk of a sound frame is a small job, while scraping and re-glazing flaking farmhouse sash is a different one. Tell whoever you hire the age of the house before they quote.
If the house is designated heritage
King Township's heritage permit form says that under the Ontario Heritage Act, owners of designated property can't alter it in a way likely to affect its heritage attributes without council's written consent. That applies to individually designated (Part IV) properties and to properties inside a Heritage Conservation District (Part V). The form lists “replacement of windows or doors” among the alterations that may need a permit, and defines alteration to include “repair”. It also says repair is generally preferred over replacement. If you aren't sure your property is designated, call King's Heritage Planning staff at 905-833-5321 before you change anything visible from outside. Fresh caulk on a sound frame is not what the form is about, but check first if there is any doubt.
Don't seal in a combustion problem
Many rural King homes heat with propane, oil or wood. Tightening the house changes how air moves, so make sure fuel-burning appliances and fireplaces still have the air they need. Ontario's Fire Code requires carbon monoxide alarms in homes with fuel-burning appliances, fireplaces or an attached garage, and TSSA reports that the requirements expanded from January 1, 2026. Test your alarms when you finish sealing. Keep alarms in the living areas, not inside the garage.
Quick answers
How do I find air leaks around my windows and doors?
On a cool, breezy day, hold a stick of incense or a tissue near the frame edges and watch for movement. Check the sill, the corners and the gap under each door.
Should I use caulk or weatherstripping?
Caulk goes on fixed joints, like where the frame meets the siding or trim. Weatherstripping goes on parts that move, like door edges and the sash of a window that opens.
What temperature is too cold to caulk?
Hydro-Québec advises against caulking below 5°C, because the compound stiffens and is hard to work. Aim for a dry day above that, so finish before the first hard cold.
Is there lead paint on my old windows?
Probably, if the house was built before 1960, according to Health Canada. Don't sand, heat-gun or blowtorch it; test the paint or hire someone set up to work safely.
Do I need a permit to reseal windows on a heritage home in King?
Not for caulk, but King's heritage office says replacing windows or doors on a designated property needs a heritage permit. Call 905-833-5321 before replacing or changing anything visible.
What a pro adds
Most re-caulking and weatherstripping is a patient afternoon for a handy homeowner. It's worth hiring out when the frames are rotted, the sash is painted shut, the house has lead paint you would have to disturb, or you'd rather not be on a ladder against a two-storey farmhouse wall. Ask for a price per window and per door that says whether old caulk removal and paint-safe prep are included. We could not find a reliable Ontario price source, so we are not quoting dollar figures here; get two or three written quotes.
If you'd like a price from a vetted craftsman, you can request one here.
Related reading
- Door installation and repair from Rhodex: get a fixed price
- More home repair guides for King City
- Sealing Foundation and Basement Cracks in an Older King Township Home
- How Do I Know If a Contractor Is Licensed in Ontario?
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