If you heat with electricity, caulking reduces your home's consumption and your bill. Beyond cutting air leaks, it stops moisture from entering the insulation or building envelope. Here's the method our crews use every day on residential jobs in Verdun, Montreal and on the South Shore.
What you need
- Get a good quality caulking compound suited to the task — cheap materials are often difficult to apply or not durable.
- Follow the instructions on the cartridge and note the recommended cleaning product (water or specific solvent).
- While caulking doors and windows, install or replace weatherstripping and seals to further limit air leaks.
- Remember that a building needs some fresh air intake — if you suspect an issue, consult a heating specialist.
- Caulk on a dry surface, free of frost and ice. Check the minimum temperature on the label: hardware-store latex can't be applied in freezing weather, while a professional silicone works even in winter.
- Have enough cartridges on hand — a standard cartridge produces a bead 6 mm (1/4 in.) wide and 7.6 m (25 ft.) long.
The 5-step method
The difference between a joint that lasts 3 years and one that lasts 15 comes down to prep — 80% of the outcome. Skip a step and it shows. To understand why lifespan varies so much, see our article on caulking lifespan.
1. Identify the area to caulk
- Visually inspect the most common air-leak sources (outlets, trim, windows, fireplaces, chimneys, access hatches).
- Look for signs of poor sealing (tears, water marks, etc.) — take a photo of suspect spots if needed.
- Slowly move a candle or thin paper around windows and at wall-floor and wall-ceiling junctions. If the flame or paper moves, there's a leak.
- Spider webs are also a good indicator: spiders spin where air circulates.
2. Clean the area to be caulked
- Make sure the area is free of dust, paint chips, and old caulking product.
- If needed, remove cracked and dried caulking with a retractable blade knife and brush the area thoroughly.
- Replace damaged wood and re-nail boards if needed.
- Insert filler material (oakum or foam backer rod) into very wide gaps (more than 6 mm or 1/4 in.).
3. Prepare the caulking cartridge
- Cut the tip of the cartridge at an angle with a retractable blade knife.
- Break the protective seal by inserting a wire or long nail into the cartridge.
4. Apply the caulking compound
- Hold the gun at a right angle and follow the crack or joint while gently pressing the trigger.
- If needed, use a disposable stick to push the compound into the gap to fill it completely.
- Make sure the compound covers the crack on both sides; add more if necessary.
- When you finish, do not release the gun trigger abruptly to avoid a mess.
5. Smooth the joint
If you're using a water-based or silicone caulking compound, dip your fingers in a bowl of soapy water then run them over the compound to smooth the joint; the soap will prevent the compound from sticking.
DIY or hire a pro
A meticulous DIYer can redo interior joints without issue. Three situations warrant a professional:
- Upper floors: working on scaffolding or at height requires proper gear and safe install.
- Exterior joints on brick or aluminum: prep demands specific know-how (old sealant removal, product choice, weather timing).
- Water-damage signs: a failing joint can hide an insulation or frame issue — better inspected. See the 5 signs that should alert you.
To prep your home for the cold beyond caulking, our preparing for winter guide gathers the complementary steps. For pricing, warranty and service-area questions: the FAQ — and for a quote, our caulking service page.
Source: Hydro-Québec