In addition to effectively reducing air leaks, it prevents moisture from penetrating the insulation or the building envelope.
A few important concepts...
- Buy a good quality caulking compound that is appropriate for the job - cheap materials are often difficult to apply or do not hold up over time.
- Follow the instructions for use printed on the cartridge and take note of recommended cleaning products (water or a special solvent).
- While you're caulking your windows and doors, take the opportunity to install or replace weatherstripping and gaskets to minimize air leakage.
- Remember that a building must have a certain amount of fresh air. If you think your home has problems in this area, talk to a heating systems specialist.
- Caulking should preferably be carried out in dry weather, and should be avoided at temperatures below 5°C (41°F), as the caulking compound will harden and be difficult to apply.
- A standard cartridge will produce a bead 6 mm (1/4") wide by 7.6 m (25') long.
1. Determine the area to be caulked
- Visually inspect the most common sources of air leaks (e.g. electrical outlets, woodwork, windows, fireplaces, chimneys, access panels).
- Look for signs of poor sealing (tears, water marks, etc.). If necessary, take a photo of suspect areas.
- Slowly hold a candle or thin sheet of paper near windows and where walls and floors join, as well as walls and ceilings. If the flame or sheet of paper moves, there's probably an air leak.
- The presence of spider webs is also a strong sign that air leaks are present, as spiders tend to weave their webs near air currents in order to catch food.
2. Clean the area to be caulked
- Make sure the area is free of dust, paint chips and old caulking.
- If necessary, remove any cracked or dried parts of the compound with a utility knife, and clean the area thoroughly with a brush.
- Replace damaged wood and nails down loose boards if necessary.
- For very wide cracks (over 6 mm or 1/4"), insert a filler material such as a plug made of packing material or a foam gasket.
3. Prepare the caulking cartridge
- Cut the end of the cartridge at an angle using a utility knife.
- Break the protective film by inserting a wire or long nail into the cartridge.
4. Apply caulking compound
- Position the gun at a right angle and move along the crack or joint to be caulked, pulling the trigger lightly.
- If necessary, use a small disposable stick to push the compound into the slot to fill it completely.
- Make sure the paste covers the crack on both sides; if necessary, add more compound using the gun.
- When you've finished applying the compound, don't release the trigger of the caulking gun abruptly to avoid making a mess.
5. Smooth the joint
If you're using a water or silicone-based caulking compound, dip your fingers in a bowl of soapy water and run them over the compound to smooth the joint; the soap will prevent the compound from sticking to your fingers.
Source: Hydro-Québec
