What you need

Caulking kit

  • Caulking gun

  • Caulking compound (such as silicone)

  • Rag

  • Bowl of soapy water

  • Foam backer rod or foam rope (if necessary)

  • Lit candle or a thin sheet of paper (if necessary)

  • Other tools (if necessary)

  • Time : 1 hour
  • Difficulty : 2
  • Investment : low
  • Yield : high

Important concepts

  • Be sure to choose a good quality caulking compound well suited to the task. Cheap compounds are often difficult to apply and lack durability.
  • Follow the instructions on the cartridge and check what you need for cleanup (water or special solvent).
  • While you are caulking your doors and windows, take the opportunity to add or replace weather stripping and gaskets as necessary, to eliminate air leaks as much as possible.
  • Remember that a building needs some fresh air coming in. If you think your house may have problems in that area, consult a heating system specialist.
  • lit candle or a thin sheet of paper (if necessary)
  • Do your caulking in dry weather, preferably. Do not try to caulk in an area where the temperature is below 5°C (41°F). The compound will become stiff and difficult to work with.
  • Purchase enough caulking. One standard-sized tube will make a bead 6 mm (1⁄4 in) wide and 7.6 m (25 ft) long.
1

Identify the areas to be caulked

  • Check the most common sources of air leakage (e.g., electrical outlets, window and door trim, windows, fireplaces, chimneys, attic hatches).
  • Look for signs of poor a seal (tears, water marks, etc.). If necessary, take pictures of suspicious locations.
  • Take a lit candle or a thin sheet of paper and move it slowly around windows and along where walls meet the floor and ceiling. If the flame or paper moves, there is likely an air leak at that spot.
  • Spider webs can be a sign of air leaks, since spiders tend to build their webs in places where air circulates.
2

Clean the areas to be caulked

  • Make sure the area to be caulked is clean and free of dirt, loose paint and old caulking.
  • Remove any split and dried old compound using a utility knife and clean the area well with a brush.
  • Replace deteriorated wood and renail loose boards.
  • If there are particularly large cracks—greater than 6 mm (1/4 in)—use a special filler such as foam rope or a foam backer rod before caulking.
3

Prepare caulking cartridge

  • Cut the nozzle on an angle.
  • Break the seal with a wire or long nail pushed down the nozzle.
4

Apply caulking compound

  • Push the caulking gun along at right angles to the crack or joint, pulling the trigger lightly.
  • If needed, use a small disposable stick to push the compound into the crack to fill it completely.
  • Make sure the caulk adheres to both sides of the crack. Add more, if needed.
  • Release the pressure lever slowly as you finish a bead to avoid dripping.
5

Smooth the joint

If you are using a water- or silicone-based caulking compound, “tool,” or finish, the bead with a finger dipped in soapy water, which prevents the compound from sticking to your finger.

Did you know?

Up to 25% of your home’s heat may be escaping. All together, air leaks could amount to a hole the size of a basketball! Fortunately, caulking is a cheap solution.

Special instructions for particular leaks

Here are some practical tips on sealing the most common air leaks.

Electrical outlets

What you need

  • Foam gaskets for outlets

  • Caulking kit (if necessary)

  • Socket safety plugs (if necessary)

  • Airtight plastic electrical box (if necessary)

Air leaks may occur at various locations in your house and each has its own special features. Take these tips for maximum weatherizing.

  • If air is leaking around outlets on outside walls, caulk them. Be sure to check outlets on inside walls, too, because they can also let air in and out.
  • First turn off the power by tripping the circuit breaker or removing the fuse. Check that it’s off by plugging in a light or other device.
  • Apply CSA-approved foam gaskets for outlets between the plate and the box.
  • Insert safety plugs in unused outlets.
  • When you install a new outlet, place it in an airtight plastic electric box that you can buy at a hardware or electrical supply store. Seal the line’s entry point and the opening in the wall’s air barrier.

Window and door trim

What you need

  • Caulking kit

  • Seal areas of air leakage around all baseboards, mouldings and window and door casings.
  • For small leaks, this can be done easily by sealing all the joints with a flexible caulk that is clear, paintable or of a matching color.
  • For major air leaks, carefully remove the trim and seal behind it. Insulate wide cracks with a foam backer rod or foam rope and seal them with caulking or the appropriate type of polyurethane foam.
  • If you remove baseboards, you might also be able to caulk between the wall finish and the bottom wall plates, and between the plates and the floor.

Glass panes (glazings)

What you need

  • Glazing compound (if necessary)

  • Putty knife

  • Hair dryer (if necessary)

  • The seal between glass and its wood frame should be tight.
  • Check the glazing carefully and be certain that all the seals are intact, with no cracks or missing sections.
  • If you find any cracks, repair them with glazing compound, which lasts longer and stays semisoft and usable longer than putty.
  • First remove the old putty with a putty knife or utility knife. If the old putty is hard and brittle, soften it up with a hair dryer.
  • Apply glazing compound with a putty knife. Press it firmly into the space for a good seal and then paint, allowing the paint to just touch the glass.

Fireplace

What you need

  • Heat-resistant caulking compound (if necessary)

  • Caulking kit (if necessary)

  • Close the chimney damper when a fireplace is not in use.
  • Take a flashlight and make sure the damper fully closes. If it does not, have it repaired by a certified chimney specialist.
  • However, even with the damper closed, a great deal of heat may still escape up the chimney. You can install tight-fitting glass doors, but be aware that most are not very tight or effective.
  • The door frame should be tightly sealed to the fireplace with noncombustible caulk.
  • The frame should include a combustion air gate or damper. The air gate permits entry of combustion air from the outside to supply the fire, but when not being used, the air gate should be closed.
  • Ask for door kits at your wood-burning appliance dealer or local building-supply outlet.
  • Seal an unused or seasonally used fireplace by putting an airtight plug of some sort in the chimney or across the fireplace opening. This can be made from board material that is cloth-covered and provides a good seal at the edges.
  • Check for air leaks where the chimney meets the wall (remove the trim if necessary). Caulk this joint with a high-temperature caulking.

There may be a large gap where a masonry chimney rises through the attic. This space can be partially sealed by stuffing it tightly with pieces of mineral wool batt. Do not use any material that is, or may become, flammable. For greater effectiveness, cut pieces of sheet metal to fit around the chimney. Seal all the joints with a flexible, heat-resistant sealant.

If you have a metal chimney rising through the attic, do not insulate closer than 50 mm (2 in.) as this can create hot spots in the chimney lining and can present a fire hazard. Instead, install a collar of metal or other fire-resistant material around the chimney and caulk to prevent air leakage into the attic.

Source : Natural Resources Canada

Chimney

Chimneys pose particular challenges for air-sealing and insulating.

SAFETY WARNING : Fire safety is a real concern when air-sealing and insulating. Refer to Fire and other hazards in attics , for methods of dealing with this area.

Attic hatch

What you need

  • Caulking kit

  • Weather stripping

  • Insulation

  • Hooks and eyes

  • Seal the attic hatch exactly as you would seal an exterior door.
  • Caulk around the frame and between the casing and the ceiling drywall.
  • Weather-strip along the edges of the casing or the access panel itself.
  • Finally, install hooks with eyebolts or some sort of latch mechanism to hold the hatch firmly against the weather stripping.
  • The hatch itself should be insulated.