Can Aeroseal duct sealing work for older Toronto homes with major leaks?

Aeroseal can be highly effective for older Toronto homes, but it has limitations — it seals gaps up to 5/8 inch, so homes with severely deteriorated ductwork, disconnected joints, or collapsed sections will need conventional repairs first before Aeroseal can finish the job. For most post-war GTA homes with typical age-related leakage, Aeroseal is one of the best options available because it seals ducts from the inside, reaching joints hidden in walls, ceilings, and enclosed chases that are impossible to access with mastic.

Aeroseal works by temporarily blocking all registers and grilles, pressurizing the duct system, and injecting a polymer-based aerosol mist into the ducts. The pressurized air pushes the polymer particles toward leak points, where they accumulate and build up a seal from the inside out. The process is computer-controlled, measuring leakage before, during, and after treatment, and provides a printout showing exactly how much leakage was reduced. In a typical older Toronto home, Aeroseal reduces duct leakage by 80 to 95 percent in a single treatment that takes four to eight hours.

Where Aeroseal excels in older GTA homes is reaching the ductwork you cannot see or touch. Many homes built in the 1950s through 1970s across Scarborough, North York, Etobicoke, and the inner suburbs have duct runs enclosed in walls, between floors, and in finished ceiling cavities. These joints have been slowly loosening for 50 to 70 years through thousands of thermal expansion and contraction cycles. You cannot apply mastic to a joint buried inside a finished wall without tearing out drywall. Aeroseal reaches these joints from the inside, making it the only practical sealing option short of major demolition.

Where Aeroseal has limitations is with large structural failures in the duct system. Disconnected duct sections, large holes from rust-through, crushed flex duct, or collapsed duct board cannot be sealed with Aeroseal — the gap is simply too large for the polymer particles to bridge. Pre-war Toronto homes with original octopus furnace ductwork often have such severe deterioration that the duct system needs partial or complete replacement rather than sealing. A qualified contractor will inspect the system before recommending Aeroseal and will identify any sections needing conventional repair first.

Another consideration for older Toronto homes is asbestos. Many homes built before 1985 have asbestos tape or insulation on ductwork. Aeroseal itself does not disturb asbestos, but the process of blocking registers and accessing the system may require handling asbestos-wrapped connections. If your home has suspected asbestos on the ductwork, professional testing and abatement must happen before any duct sealing work — asbestos abatement typically costs $2,000 to $5,000 in the GTA.

Aeroseal in the GTA costs $1,500 to $3,500 for a typical home, depending on system size and complexity. For an older home with significant leakage, the energy savings alone — typically $300 to $800 per year — provide a payback within three to five years. Combined with improved comfort, reduced dust infiltration, and better humidity control, Aeroseal is often the most cost-effective single upgrade an older Toronto home can receive. Ask potential contractors for before-and-after leakage measurements to verify results.