Caulking and energy: how much can you save?

Air leaks by the numbers

The Government of Quebec gives two benchmarks. First, air leaks alone can cause 25% of a home's heat loss. Second, poor airtightness can push the energy bill up by as much as 15%.

In the United States, ENERGY STAR estimates that sealing leaks and insulating can save up to 10% on the annual energy bill. Note that this figure combines two jobs: air sealing and insulation.

Natural Resources Canada doesn't give a percentage, but its message is clear: air leakage control comes first among the renovation work to do in a home.

A word on what these sources don't say. The Government of Quebec gives no percentage of heat loss specific to doors or windows. If someone gives you a precise number for your windows, ask where it comes from.

Finding your leaks

You can do a first check yourself. The Government of Quebec suggests the candle test: hold a flame or a stick of incense near frames and outlets. If the smoke moves or bends, air is getting through. Be careful with a flame near curtains and blinds.

For a precise measurement, there is the blower door test. An advisor measures the airtightness of the whole house. The test takes about 30 minutes. The result is expressed in air changes per hour, or ACH. It is done with specialized equipment, by an energy efficiency advisor.

The blower door test has one advantage: it gives a number before and after the work. That way, you know what your own home gained.

Everyday signs count too. A curtain that moves with the window closed, a frame that feels cold, condensation that keeps coming back in the same corner: these are clues to note before the assessment.

The spots to watch

Leaks are found mostly at junctions. According to the Government of Quebec, the problem often comes from the installation, not the window itself: it is the joint between the frame and the wall that lets air through. For this joint, the Government of Quebec recommends low-expansion foam and caulking.

The list of components to caulk under Hydro-Québec's LogisVert measure gives a good picture of the sensitive spots:

• windows, exterior doors and patio doors
• attic access hatch
• range hood and bathroom fan
• electrical outlets
• fireplace

The leaks people forget

The attic access hatch is a classic. Warm air rises and escapes through it. Natural Resources Canada and ENERGY STAR recommend putting weatherstripping on its frame and securing the hatch well.

Doors and operable windows need weatherstripping in good condition, on top of caulking around the frame. According to ENERGY STAR, caulk is for fixed components and weatherstripping is for moving parts. One without the other is not enough.

Finally, think about moisture. The Government of Quebec recommends caulking the inside first, to keep moist indoor air out of the walls, then the outside against the rain. It is good for the bill, and good for the structure.

Caulking and roof insulation go together

Air sealing and insulation complement each other. A well-insulated attic loses less heat, but warm air leaking through a hatch or a light fixture keeps rising. The reverse is also true.

Hydro-Québec's LogisVert "roof insulation and caulking" measure pairs the two jobs. It offers up to $1,500, depending on eligibility. Caulking alone does not qualify. The insulation can be done separately, by the contractor of your choice. Paired together, the work is eligible. Our other division, Région Isolation, does attic insulation.

A few important points. The homeowner applies, not the contractor. No amount is guaranteed. We are a private contractor: we are neither mandated nor accredited by any program. And programs don't go door to door. If someone rings your doorbell in the name of a program, be wary.

The limits of savings figures

Notice the words "up to" and "can" in the official numbers. These are ceilings, not promises.

What you save depends on your home: its age, its condition, how it is heated, the quality of the insulation and how leaky it is to begin with. A house that is already airtight will gain little. An old, draughty house will gain more.

That is why we don't promise you a percentage. We show you the damaged joints, explain what we will redo and give you a written quote. If you want a measured number, a blower door test before and after is the tool to use.

Comfort, on the other hand, you feel every day: fewer draughts near the windows and frames that feel less cold.