Ductwork Replacement Cost Ontario 2026: When It's Worth It and What to Expect

When does ductwork actually need replacing

Most homeowners who call a contractor about ducts end up needing repair, cleaning, or sealing rather than full replacement. The three situations where replacement is genuinely the right answer are structural failure, contamination that survives cleaning, and undersized ducts that cannot support new high-efficiency equipment. Homeowner guidance from the trades consensus is that duct replacement is worth it when ducts are over 15 years old, leaky, or physically damaged, since sealed modern ductwork can improve HVAC efficiency by a meaningful margin and reduce dust and allergens in the home.[13]

Age alone is a weak trigger. Rigid galvanized sheet metal trunks routinely last 50 years or more if they stay dry, and many Ontario homes built in the 1970s are still running their original trunks without issue.[13] Flexible insulated ducts and fiberboard plenums have shorter useful lives and tend to need replacement sooner, but that is still 20 to 25 years in most homes rather than a fixed decade.

The stronger triggers are functional. If a contractor pressure-tests your ducts and finds leakage well above typical norms, if a visual inspection shows crushed flex runs or disconnected boots, or if you are moving from a basic furnace to a variable-speed or heat pump system that needs more return air than the existing ducts can deliver, replacement earns its price. Otherwise, start with sealing and targeted repair.

Signs of duct failure versus duct cleaning territory

Homeowners often conflate three different problems, duct dirt, duct leakage, and duct capacity, and contractors sometimes sell replacement when cleaning or sealing would have solved the issue. The Government of Canada's guidance on indoor air quality treats duct filtration and regular filter replacement as the primary lever for dust and allergen control, not duct replacement.[15]

Symptoms that point to duct problems rather than equipment problems:

• Rooms farther from the furnace that are consistently hot or cold regardless of season
• Whistling or roaring at registers, which usually means a static pressure issue from undersized ducts or a crushed flex run
• Visible dust reappearing within days of surface cleaning, which suggests leakage pulling unconditioned attic or basement air into the supply stream
• Obvious disconnections, torn flex insulation, or fallen-out boots visible in the basement or mechanical room

Symptoms that usually point to equipment or sizing, not ducts, include short cycling, a furnace that cannot reach set temperature on the coldest days, high energy bills with no change in usage pattern, and rising repair frequency on aging equipment. Duct repair as a general category runs $200 to $2,100, with sealing small leaks at $250 to $700 and reattaching loose joints or repairing fractured areas at $300 to $1,200.[4][12] If you can fix the problem at the repair price, replacement is overkill.

Cost ranges for partial vs full replacement

Ductwork replacement pricing in Ontario in 2026 follows a predictable curve. Small homes or partial replacements sit at the low end, standard full replacements in mid-size homes cluster around the $3,500 average, and large or complex homes with difficult access push toward and past $10,000.[11] Published North American averages for 2026 converge on roughly $1,400 to $5,600 for new ductwork installation or replacement on a typical home, with a national average near $3,500 once you normalize across home sizes.[5][11]

Material choice is the second biggest driver after home size. Flexible insulated duct is the cheapest option on an installed basis, with material costs on the order of $2 to $4 per linear foot, while rigid galvanized sheet metal costs roughly $7 to $13 per linear foot for material alone.[13] Fully installed, a flex run comes in at the low end of the $10 to $30 per linear foot range, and sheet metal sits at the top of that band, reflecting both the material cost and the labour time to fabricate and hang rigid trunks.[2]

Sizing the job in advance is easier than most homeowners expect. A reasonable estimate is 0.5 linear feet of duct for every square foot of floor area served, so a 2,000 square foot home needs roughly 1,000 linear feet of new duct in a full replacement.[13] Multiply by your per-foot installed range and you get a pre-quote ballpark that you can use to sanity-check contractor numbers. Every supply register and cold air return also needs a boot and sealing work, which adds about $250 per vent in labour and materials.[13]

Adding new runs for a room or addition

Adding ductwork to reach a space the original system did not serve is far cheaper than replacing a working system. The standard per-run cost for replacing or adding an individual duct is $270 to $500 installed,[5] and adding a single new vent or register to existing trunks runs $250 to $500.[5] These numbers assume reasonable access through an unfinished basement, a drop ceiling, or an attic, with no major finishing work required.

Common add-a-run situations and their typical all-in cost, labour and materials included:

• New vent to a finished basement bedroom from an existing trunk: $250 to $500 if the trunk passes near the room, higher if a new branch run is needed
• New run to a bonus room above a garage: $400 to $900 typically, depending on access above the garage ceiling
• Duct extension into a small addition, one supply and one return: $800 to $1,800 for the HVAC work alone
• Whole-addition ductwork, 2 to 4 supply runs plus a return trunk: $2,000 to $5,000 for HVAC work before drywall repair

The hidden cost on add-a-run jobs is drywall and paint work when the contractor has to open finished walls or ceilings. Budget another $500 to $1,500 for patch, prime, and paint, and always get the HVAC scope and the drywall scope quoted separately.

What Ontario contractors typically charge for sealing

Duct sealing is the single most underrated spend in residential HVAC. It addresses the real problem in most older Ontario homes, joint leakage between the furnace and the registers, and it costs a fraction of replacement. Published Ontario and North American pricing for 2026 lands in consistent ranges:

• Manual sealing with mastic at joints: about $2,250 for a typical home,[3] or $0.50 to $1.50 per square foot of home floor area on the low end[3]
• Aerosol sealing, branded as Aeroseal: about $1,300 for a small system,[3] with a broader published range of $1,500 to $6,900 depending on system size[6]
• All-in professional duct sealing, any method: $1 to $2 per square foot of home floor area, or roughly $1,000 to $6,000 total for most Ontario homes[6]

By home size, typical total sealing cost scales predictably from about $1,000 to $2,000 at 1,000 square feet up to $3,000 to $6,000 at 3,000 square feet.[6] Those totals include pre- and post-sealing pressure tests, which you should expect on any legitimate quote so you can verify the work actually tightened the system.

Pure duct cleaning in Ontario, which is different work entirely, averages $300 to $600 per home depending on size and condition.[8] Cleaning moves dust and debris out of the ducts but does not fix leakage or structural issues, so it should not be the answer to comfort or energy-bill complaints unless there is obvious visible contamination. The common pattern across Ontario pricing is that cleaning sits around $300 to $600, sealing sits around $1,000 to $6,000, and replacement sits at $2,000 to $12,000+, with each step solving a different problem.[8][6][11]

How ductwork ties into a new furnace or AC install

The most common reason an Ontario homeowner gets a surprise ductwork quote is during a furnace, AC, or heat pump replacement. HVAC installations in Ontario range from $5,000 to $18,000 depending on system type and complexity,[14] and when ducts cannot support the new equipment, contractors add duct modifications to the scope rather than oversell a replacement that the ducts will choke.

Typical ductwork change-orders that show up on equipment-replacement quotes:

• Return air trunk resizing, $800 to $2,500, when a new variable-speed furnace or heat pump needs more return cubic feet per minute than the old system
• Supply trunk extension or replacement of a crushed run, $1,200 to $3,500, usually to unblock a bottleneck that limits a full floor
• New register and boot installations to rebalance airflow, $250 per vent[13]
• Full duct replacement bundled with the equipment, which is rare and usually indicates the ducts were already failing on their own

On a heat pump retrofit in particular, expect the duct scope to be larger. Cold-climate heat pumps deliver conditioned air at lower temperatures than gas furnaces, which means higher runtime and more total air movement. Undersized returns that never caused a problem with a short-burst gas furnace can become the main comfort bottleneck once a heat pump is doing most of the work. When comparing new-system quotes, always check that the duct scope is itemized, not buried in a single lump sum, so you can see whether the contractor priced real duct work or just left a placeholder.[10]

For the equipment side, see the HVAC replacement cost guide and the HVAC costs pillar.

What to ask in a ductwork quote

Quotes for ductwork vary more than quotes for equipment because the work is harder to standardize. Two legitimate contractors looking at the same basement can legitimately disagree on whether a trunk needs replacing or can be patched, whether flex or sheet metal is the right material, and how much access work is required. A clean quote should spell out:

• Linear feet of new trunk and branch duct, broken out by material
• Material choice, galvanized sheet metal, flex, or fiberboard, and why the contractor chose it
• Count of supply registers and return grilles, with boot and sealing work itemized at the per-vent rate
• Method of sealing at joints, mastic and mesh, aerosol, or foil tape, and whether a pre- and post-test is included
• Whether the sheet metal will be fabricated in-shop or on-site, which affects both cost and finish quality
• Haul-away and disposal of old ducts, which should be a line item, not assumed
• Drywall and paint scope, explicitly included or explicitly excluded
• Whether the project requires a permit, for large-scope work some Ontario municipalities require mechanical permits even on duct-only jobs

Red flags are the same as on any HVAC quote. One lump sum with no breakdown, pressure to sign the same day, vague material descriptions, or a refusal to pressure-test before and after sealing are all reasons to get a second quote. The spread is larger on ductwork than on equipment because scope interpretation varies more, so two honest contractors can legitimately quote $1,000 apart.[14] Get three quotes, normalize the scope, then decide.

For context on what a good contractor looks like generally, see how to choose an HVAC contractor in Ontario and the broader red flags guide.

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