What does it cost to repair a collapsed duct run in a Toronto home?

Repairing a collapsed duct run in a Toronto home typically costs $150 to $600 for a straightforward patch or reconnection, or $300 to $1,500 if the entire run needs replacement. The final price depends on what collapsed, why it collapsed, what material the duct is made of, and how accessible the damaged section is.

Flex duct collapses are the most common scenario in GTA homes. Flex duct running through attics, crawlspaces, and between floor joists sags over time as the support straps stretch or detach. Once flex duct sags enough, the weight of the insulation layer compresses the inner liner, restricting airflow to a trickle. The room served by that run becomes noticeably hotter in summer and colder in winter, often prompting the homeowner to investigate. Repairing a collapsed flex duct run usually means replacing the entire section rather than patching — a new flex duct run costs $8 to $18 per linear foot installed, so a typical 10-to-20-foot bedroom branch run costs $150 to $400 to replace. The contractor should install proper support strapping every 4 feet and ensure the duct is pulled taut with no sags or kinks.

Rigid metal duct collapses are less common but do happen, particularly in older GTA homes where decades of temperature cycling have weakened joints. A disconnected joint at a trunk-to-branch connection is a simple repair — reconnect, fasten with sheet metal screws, and seal with mastic and UL 181 foil tape for $150 to $300. A crushed or dented rigid duct section, often caused by someone stepping on ductwork in an attic or stacking heavy items against basement ducts, requires cutting out the damaged section and splicing in new material, costing $200 to $600 depending on the duct size and location.

The hidden cost of a collapsed duct is the energy you have been wasting. A fully collapsed branch run means your furnace and air conditioner have been producing conditioned air that never reaches the intended room. Meanwhile, you may have been running space heaters or portable AC units to compensate, driving up energy costs. If the collapse is in an unconditioned space like an attic, the conditioned air has been dumping directly into the attic — heating or cooling the outdoors at your expense.

Accessibility is the biggest cost variable. A collapsed duct in an unfinished basement is a quick repair because the contractor can see and reach the damage. A collapsed duct inside a finished ceiling, wall cavity, or a cramped attic with blown insulation covering everything requires significantly more time and may involve cutting access holes in drywall (add $100 to $300 for drywall repair). If you suspect a collapsed duct but cannot find it, a contractor can use a duct pressure test or airflow measurement at each register to identify which run is compromised. Toronto Ductwork can match you with a local ductwork professional for a free assessment.