Air leakage costs  households a hefty part of their annual heating bill and makes our homes uncomfortable and unhealthy. This fact sheet shows you what to do about it.

 

Why Should I Worry about Air Leakage Problems?

Brrrrr... Why is this room so uncomfortable?—Cold air leaking into your house can make some rooms—particularly in the basement, on the main floor or with a windward facing wall—drafty, uncomfortable and difficult to heat, even with the thermostat turned up.

Zappp! My house is a desert!—Shocks from static electricity, creaky furniture, dry throats and skin, laundry that "clings": these are symptoms of excessive winter dryness. Cold, dry outdoor air leaking into your house is one of the villains. This air leakage reduces the relative humidity in your home. Lower humidity levels also aggravate allergies and respiratory problems. Health Canada recommends a minimum of 30% relative humidity.

What's happening to my attic?—Warm air leaking out of your house carries moisture in the form of water vapor. This moisture condenses in attic spaces and wall cavities, causing long-term deterioration. Problems include rotting roof sheathing, wet insulation, mould growth, buckled siding, spalling bricks and puddles in basement corners. (Natural Resources Canada has published a fact sheet entitled Moisture Problems.)

What am I breathing?—We need fresh air in our houses. But do we really want that fresh air to be dragged in through floor drains, dusty insulation and chimney flues? Wouldn't a mechanical ventilation system, with air filtering, be healthier?

How do these bugs get in?—Crawling and flying insects make their way into your house in the summer via many of the same routes taken by air leakage in the winter. And if you have mice, just imagine how big those cracks are!

Yikes! Look at this heating bill!—Air leakage represents 25-40% of the heat lost from an older home. This costs you an average of $150-250 per year, if you heat with natural gas, and $200-350 per year for an electrically heated home.

Won't anyone buy my house?—Most consumers will avoid buying a house that is drafty, uncomfortable, expensive to heat or has moisture problems. A leaky house usually has a lower resale value.

Does My House Have a Problem?

• Are some rooms drafty or difficult to keep warm?
• Is there a lot of static electricity in mid-winter?
• Is my heating bill higher than average?
• Are there moisture problems in my attic—damp insulation, mildew or rot?

How to detect air leaks?
Cold air leaking into your house—at door sills or basement windows—is easy to detect, because you can feel the draft. However, warm air leaking out of your house—at ceiling light fixtures or upper story windows—is almost unnoticeable.

Some contractors and consultants perform a fan depressurization test (also called a blower-door test) to calculate the airtightness of a house and use a smoke pencil to identify the location of air leaks. This test costs about $125-200 but may be worth considering if you are undertaking a major retrofit project.

You can take a simpler approach by using a household item as a "draft detector"—an incense stick, a thin piece of tissue or cellophane, or a feather glued to a toothpick.

It's best to inspect your house on a very cold or windy day. Put on your detective's cap, grab your draft detector and go through the entire house, holding the draft detector near window and door frames, electrical outlets, baseboards and other possible leakage locations. You may be surprised by what you find. (By the way, this type of inspection can also be done when you want to buy a house.)

Where to look? Here are some of the key locations to check: 1) attic hatch 2) ceiling penetrations into attic 3) doors 4) exhaust vents 5) mail slot 6) sill and header 7) service entries 8) floor drain 9) foundation cracks 10) electrical outlets 11) windows 12) chimney

How to Solve Air-Leakage Problems and Save Energy

Weatherstrip and caulk windows and doors—A good place to start reducing air leakage is at windows and doors—your home's "Achilles heel". On traditional single-hung windows, apply V-strip and compression-type weatherstripping. Horizontal sliders need pile-type weatherstripping. Hinged windows—casement, awning and hopper types—require combinations of V-strip and compression weatherstripping on the fixed and movable sash. Sash locks may also need to be replaced or adjusted to ensure a snug fit.

For exterior doors, reduce air leakage around the jambs (sides and top of door) by adjusting the position of the weatherstripping or replacing it if worn. Door sills need a threshold seal, door bottom seal or a door sweep. Sliding patio doors can be sealed like sliding windows.

Weatherstripping single-hung windows 1) Weatherstrip side jambs 2) Weatherstrip check rails 3) Weatherstrip sill

Upgrade or replace windows—In addition to losing heat through air leakage, conventional single- or double-glazed windows have little insulating value.

Door jamb details 1) jamb 2) weatherstripping at face of door 3) weatherstripping at edge of door 4) door

If you are thinking about replacing older deteriorated windows, consider upgrading to high-performance windows that have special "low-E" coatings and are filled with inert gases like argon or krypton. The additional cost is usually less than 10 per cent and the energy savings are considerable. For more information on energy-efficient windows, refer to the Natural Resources Canada publication entitled, Consumer's Guide to Buying Energy-Efficient Windows and Doors. See the last page of this fact sheet to find out how to order a free copy.

Apply thin plastic film to improve airtightness and insulating value.

Seal hidden openings into the attic—There are many air leakage paths into the attic: passages for electrical wires, electrical boxes for ceiling lights, plumbing stack, chimneys, exhaust vents and the tops of partition walls. Addressing these can be a miserable job but well worth the effort. Pull away attic insulation, a little at a time, to expose these hidden leakage paths. Caulk or foam electrical wiring openings, exhaust fan housings and tops of walls. Use heavy polyethylene, a pipe clamp and acoustical sealant to seal around the plumbing stack.

Sealing plumbing penetrations into the attic 1) pipe clamp 2) plumbing stack 3) acoustical sealant. 4) sealed polyethelene.

Some types of recessed lighting fixtures can present a fire hazard if sealed or covered with insulation and should be replaced with ceiling-mounted or wall-mounted fixtures, or fixtures that are airtight and approved to be covered with insulation.

Use sheet metal and non- combustible caulking to close the gap around chimneys.

Sealing lighting and wiring penetrations into the attic

1) caulking along interior wall junctions 2) sealed wire hole 3) electrical box 4) sealed polyethylene