Ductwork replacement cost dataset
This is the complete dataset behind the ductwork calculator, at national wage rates. It is built around a comparison the trade rarely offers unprompted: sealing what is already there against replacing it. On the reference house sealing is 30% of a full replacement, and in many homes it fixes most of what a replacement would. Last reviewed 2026-08-23.
Three scopes on the same house
National wages, 2,000 square feet, single storey, flexible duct in an attic.
| Scope | Duct replaced | Trade hours | Cost |
|---|---|---|---|
| Seal what is there and test it | — | 21.6 | $2,142 |
| Replace the trunk lines, keep the branches | 80 ft | 21.6 | $3,086 |
| Replace the whole duct system | 332 ft | 61.1 | $7,152 |
The middle row is the one that gets skipped in conversation and is often the right answer: the trunks carry every cubic foot of air and are where undersizing does the damage, while the branch runs are frequently fine. ⚠️ Worth stating the incentive plainly — a full replacement is worth roughly 3 times as much to whoever is advising you as sealing is. That is not an accusation of dishonesty. It is a reason to ask for the cheap option by name and to insist on a pressure test before choosing.
Where the ducts run
| Location | Labour factor | Trade hours | Cost |
|---|---|---|---|
| Basement or open ceiling | ×1 | 43.4 | $6,131 |
| Crawl space | ×1.4 | 59.1 | $7,036 |
| Attic | ×1.45 | 61.1 | $7,152 |
Duct is not expensive; getting to it is. This is one of the most labour-heavy jobs on the site, which is also why the regional wage index carries more of the figure here than any material choice does.
The quantity rules, and what they are not
| House | Trunk | Outlets | Branches | Sealing | Full |
|---|---|---|---|---|---|
| 1,200 | 48 ft | 8 | 144 ft | $1,609 | $4,767 |
| 1,600 | 64 ft | 11 | 198 ft | $1,876 | $5,957 |
| 2,000 | 80 ft | 14 | 252 ft | $2,142 | $7,152 |
| 2,600 | 104 ft | 18 | 324 ft | $2,530 | $8,785 |
| 3,200 | 128 ft | 22 | 396 ft | $2,911 | $10,413 |
⚠️ Three rules of thumb produce those quantities and none of them is official: one supply outlet per 150 square feet of floor, one foot of trunk per 25 square feet, and branch runs averaging 18 feet each. They are what the trade uses to size up a quantity before anybody measures. Designing a duct system properly is a calculation, and the professional standard for it is licensed material this site does not reproduce or derive from. What is priced here is installing ducts, not designing them.
Flexible against rigid
| Material | Hours per foot | Trade hours | Cost |
|---|---|---|---|
| Insulated flexible duct | 0.09 | 61.1 | $7,152 |
| Rigid sheet metal with external wrap | 0.2 | 124.7 | $12,931 |
Rigid sheet metal is 181% of the flexible figure, and most of the gap is labour rather than material. The honest version of the argument: flexible duct is not a bad product, it is a product whose performance depends entirely on whoever installed it having pulled it taut. A sagging run has several times the resistance of the same length done properly, it sits above a ceiling, and nobody ever goes back to look.
Line items
51% of the reference total comes from estimated rather than official figures. On a job this labour-heavy the official half — the regional wage — is doing more of the work than usual.
| Line item | Unit | Material | Equipment / hr | Trade | Data |
|---|---|---|---|---|---|
| Mastic, mesh and mechanical fasteners1 when the ducts are sealed rather than replaced | each | $90 – $240 | — | — | estimated±45% |
| Sealing accessible joints and pressure-testing10 hours × access factor × storey factor × (floor area ÷ 2,000) | hour | — | — | Sheet Metal Workers | sourced |
| Insulated flexible duct and fittingslinear feet replaced, in flexible duct | linear ft | $3.20 – $7.50 | — | — | estimated±40% |
| Rigid sheet metal duct, wrap and fittingslinear feet replaced, in rigid sheet metal | linear ft | $7.50 – $16 | — | — | estimated±36% |
| Fabricating, hanging and connecting ductfeet replaced × hours per foot for the material × access factor | hour | — | — | Sheet Metal Workers | sourced |
| Supply and return plenums1 when trunk lines are replaced | each | $160 – $420 | — | — | estimated±45% |
| Boots and takeoffs at each outletone per supply outlet, on a full replacement | each | $18 – $46 | — | — | estimated±44% |
| Registers, diffusers and return grillessupply outlets plus returns, when the grilles are renewed | each | $14 – $48 | — | — | estimated±55% |
| Adding a return where there is noneone per storey, when returns are added | each | $120 – $320 | — | — | estimated±45% |
| Cutting in and connecting returns3.5 hours per return × access factor | hour | — | — | Sheet Metal Workers | sourced |
| Stripping out and disposing of the old ducts20% of the install hours, at the labourer wage | hour | — | — | Construction Laborers | sourced |
| Skip and tipping fee1 when the old ducts are taken away | each | $120 – $340 | — | — | estimated±48% |
| Airflow measurement and balancing4 hours after a replacement, 2 after sealing | hour | — | — | Sheet Metal Workers | sourced |
| Mechanical permit and inspection1 when a replacement is permitted | each | $80 – $300 | — | — | estimated±58% |
The reasoning behind each figure
Written out so a sheet metal contractor can point at the exact assumption that is wrong.
- Mastic, mesh and mechanical fastenersestimated, ±45%
- A bucket of mastic, a roll of mesh and a box of screws and straps. That is genuinely the whole material cost of sealing a house.
- It is listed on its own because seeing how little it is next to the labour beside it is the argument: what you are buying when you seal ducts is somebody’s afternoon, not a product.
- Sealing accessible joints and pressure-testing
- Ten hours on a single-storey house, scaled by how hard the ducts are to reach and by how many there are. Every accessible joint, boot and plenum seam gets mastic, and the result is measured rather than assumed.
- ⚠️ The word doing the work here is "accessible". Joints buried in a finished ceiling cannot be sealed from outside, and a quote that promises to seal everything in a two-storey house without opening anything is promising something it cannot deliver.
- Insulated flexible duct and fittingsestimated, ±40%
- Duct, the fittings, takeoffs, straps and tape. Priced by the foot of duct actually installed, not by floor area.
- Less than half the material cost of rigid sheet metal, and under half the labour. That is the whole reason it dominates new construction.
- Rigid sheet metal duct, wrap and fittingsestimated, ±36%
- Galvanised duct with an external insulation wrap, plus fittings and hangers. Roughly twice the material of flexible duct and over twice the labour to install.
- What it buys is a duct that holds its shape for the life of the house, can be cleaned properly, and does not depend on whoever pulled it having been careful.
- Fabricating, hanging and connecting duct
- Around 0.09 hours per foot for flexible duct and 0.2 for rigid sheet metal, scaled by how hard the space is to work in. Sheet metal is more than twice the time because it is cut, folded and hung rather than unrolled.
- These hours are our estimate. There is no public productivity data for residential trades — RSMeans publishes it and it is licensed material we neither reproduce nor derive from.
- Supply and return plenumsestimated, ±45%
- The boxes immediately above and below the equipment, from which everything else branches. Always fabricated rather than bought, and always remade when the trunks are.
- Boots and takeoffs at each outletestimated, ±44%
- The transition from round duct to the rectangular opening in a floor or ceiling. One per supply outlet, and the place where leakage into the joist bay is most common and least visible.
- Registers, diffusers and return grillesestimated, ±55%
- The only part of a duct system anybody ever sees, and the cheapest. Band separates a stamped steel register from an adjustable aluminium diffuser.
- Adding a return where there is noneestimated, ±45%
- The commonest defect in American duct systems is not leakage, it is not enough return. Air that is pushed into a room has to get back, and a house with one central return and closed bedroom doors is pressurising rooms against themselves.
- One per storey is the assumption here. The symptom of getting this wrong is a bedroom that never reaches the thermostat’s temperature no matter what the equipment does.
- Cutting in and connecting returns
- Three and a half hours per return: find a bay that works, cut the opening, build the connection and get it back to the plenum.
- Stripping out and disposing of the old ducts
- Roughly a fifth of the time it takes to install the new ones, priced at the labourer wage because that is the skill it needs.
- ⚠️ Not priced here, and it matters: duct joints and flue cement in houses from before the eighties can contain asbestos. That is tested rather than disturbed, and abatement is licensed work with its own pricing. It is listed as an exclusion.
- Skip and tipping feeestimated, ±48%
- Old flex duct is fibreglass and plastic and has almost no scrap value, unlike sheet metal. Band reflects both cases plus local tipping rates.
- Airflow measurement and balancing
- Four hours to measure what actually comes out of each outlet and adjust the dampers until it matches what the room needs.
- This is the step that turns a duct system into a working one, and the first thing dropped from a cheap quote. Ducts that have never been measured are ducts nobody knows the performance of, including the person who installed them.
- Mechanical permit and inspectionestimated, ±58%
- Duct replacement is permitted work in most jurisdictions. Fees are set locally with no national schedule, hence a band rather than a figure.
Not included in this dataset
- Opening and repairing finished ceilings and walls
- In a house with no accessible route to the ducts, the drywall work is a large share of the job and depends entirely on the route. It cannot be estimated from floor area, so it is left out and said so rather than averaged in.
- Asbestos testing and abatement
- Duct tape, joint compound and flue cement from before the eighties can contain it. Testing comes first, abatement is licensed work, and neither is priced here.
- A Manual D duct design
- Sizing ducts properly is a calculation, not a rule of thumb, and the professional standard for it is licensed material this site does not reproduce. What is priced here is installing ducts, not designing them.
- Heating and cooling equipment
- This is the ductwork alone. The furnace, air conditioner or heat pump that feeds it is priced on its own page.
- Duct cleaning
- A different job done by different people with different equipment, and one worth reading about before buying. Priced on our duct cleaning page.
Use the calculator, read what EPA says before buying duct cleaning, or read the full method.