What does it cost to replace flex duct with rigid metal in a GTA home?

Replacing flex duct with rigid metal ductwork in a GTA home typically costs $200 to $600 per run for individual branch replacements, or $3,000 to $8,000 for a whole-house flex-to-rigid conversion, depending on the number of runs, accessibility, and the length of each duct. Most GTA homes built between the 1970s and 2000s have flex duct for branch runs connecting the main trunk to individual room registers, and after 20 to 40 years, much of this flex duct is sagging, kinked, disconnected, or compressed — all of which dramatically reduce airflow.

The per-run cost breakdown is straightforward: rigid round galvanized steel duct runs $10 to $20 per linear foot installed, compared to $8 to $18 per linear foot for flex duct. While the material cost difference is modest, rigid metal duct delivers significantly better airflow performance. A typical 6-inch flex duct branch run has roughly the same friction loss as a 5-inch rigid metal duct because of the corrugated interior surface — meaning flex duct effectively reduces your duct size by about one inch compared to smooth rigid metal. Replacing a 6-inch flex run with a 6-inch rigid run can increase airflow to that room by 15 to 25 percent without any other changes to the system.

For a typical 1,500 to 2,500 square foot GTA home with 10 to 15 flex duct branch runs, a full conversion to rigid metal runs $3,000 to $6,000 if the ducts are accessible in an unfinished basement, or $5,000 to $8,000 if the runs are in an attic, crawlspace, or enclosed ceiling where access is limited. Attic work in Toronto homes is particularly labour-intensive — GTA attics reach extreme temperatures (50+ degrees in summer, well below freezing in winter), and working in cramped attic spaces with insulation is slow and physically demanding, which drives up labour costs.

Not every flex duct run needs replacement. Prioritize replacing flex ducts that are kinked or crushed (reducing airflow by 50 percent or more at each kink), runs that have disconnected from the trunk or register boot (dumping conditioned air into the attic or basement ceiling), runs longer than 25 feet (where flex duct friction losses become severe), and any flex duct with torn or missing vapour barrier in unconditioned spaces (causing condensation and insulation damage). A skilled contractor can assess each run individually and recommend which ones to replace and which are still performing adequately.

When replacing flex with rigid metal in an attic, insulating the new rigid ducts with R-8 duct wrap is essential — add $1.50 to $3.00 per square foot for insulation. All joints on new rigid metal ductwork should be mechanically fastened with sheet metal screws and sealed with duct mastic and UL 181 foil tape. This belt-and-suspenders approach to sealing ensures the joints remain airtight through decades of GTA temperature cycling.

Get at least three quotes and ask each contractor to specify which runs they recommend replacing and why. Toronto Ductwork can match you with experienced ductwork professionals through the Toronto Construction Network for free estimates.