Duct sealing

A first hand account from Tim Grant, a Harbord Villager

Photo of homeowner and installers
A celebratory photo with Tim and the Aeroseal Tech technicians, after completing their work on his Robert Street home


Why consider sealing your home’s ducts

If you live in an old house that has air ducts for heating, cooling and ventilation, your home would likely benefit from having those ducts sealed. The improvement in your home’s comfort and energy efficiency could be significant. It certainly was with ours.

Decades after they were installed, the ducts in most old houses will have many leaks as a result of the natural shifting that occurs with changing weather and other factors. Some occur in the joints where one section of sheet-metal joins another. Others are located in walls where ducts pass through. And all too often, sections of ductwork in walls have become disconnected from each other. Suffice it to say, the more leaks and disconnections you have, the less air is being delivered to the rooms in your home.

What work is involved

Retrofit duct sealing (sometimes referred to as aerosealing) has only been available in Canada for a few years. It involves pumping a non-toxic aerosol polymer glue through the ductwork in order to seal leaks up to 5/8” across. The company that you hire will be in your house for 4-8 hours. They will begin their work by measuring the existing airflow through each duct. Once measured, they will pump the aerosol polymer through each duct. Then the technicians will use sensors to detect which ducts have larger holes. In about 90% of homes, duct sections within walls have become disconnected. To reconnect them, they cut a hole in a wall or ceiling and do the repair. After all the holes and leakage spots are sealed, they once again measure the airflow in each duct. If all the holes having been sealed, the measurements will show a much stronger airflow.

The technician’s last task will be to balance the airflow between ducts. In our house on Robert Street, some rooms received much more air than others. Now the airflow is much more even room to room.

With the work now completed, our leaky house heats much faster than before. This has allowed us to program our thermostat so that our furnace runs for a much shorter time each day.

Costs, rebates and funding

At $3,000, the cost wasn’t cheap, but the added comfort and energy savings during the heating and cooling seasons is a benefit that should last decades.

There are several Toronto-area companies that do this work. We chose Aeroseal Tech and were impressed. A friend in neighbouring Seaton Village chose DAVESDUCTS and was also pleased with their work. For her house the duct sealing reports indicated reductions of 88% in duct leakage in one half of the house, and 91% in the other half. She paid a total of $2400, which included repairs to a couple of ducts that didn’t reach the top of the house.

For details on the City of Toronto’s HELP loan program that could help with installation costs, as well as the required home energy assessment, visit the Net Zero Project’s Home Retrofit Programs page. 

If you have questions or want to hear the experiences of others who have had their homes duct sealed, consider joining the Home Retrofit Forum Facebook group. 

Tim Grant

Robert Street, Harbord Village