New HVAC ductwork installation runs $2,000–$8,000 for a typical 2,000 sq ft home. The range reflects the two variables that matter most: the material you choose (sheet metal vs. flex duct) and the difficulty of routing duct runs through your home’s structure.
Before you approve ductwork
- 1How did you measure the leakage — a duct blaster test, or a visual estimate?
- 2What’s actually being sealed or replaced, and what’s being left alone?
- 3Can you show me before/after airflow numbers, not just “it’ll feel better”?
- 4Is insulation included where ducts run through unconditioned space?
- 5What’s the warranty on the sealing method or materials used?
- 6Will this change my system’s static pressure, and did you check for that?
What the job actually costs
| Scenario | Typical cost |
|---|---|
| New ductwork for a 2,000 sq ft home (flex) | $2,000–$5,500 |
| New ductwork for a 2,000 sq ft home (sheet metal) | $4,000–$8,000 |
| Per linear foot (flex duct branches) | $25–$35 |
| Per linear foot (sheet metal trunk line) | $35–$55 |
| Per trunk-to-register run (branch + register) | $270–$500 |
Labor is a significant portion of the total. Routing duct through finished walls, around joists, or through tight attics takes more time than an open basement or crawlspace install.
When you need ductwork installation
Ductwork installation is required in these situations:
Adding central AC to a home without it. Older homes heated by radiators, baseboard heat, or wall units often have no duct system. Adding central air means routing ducts from scratch through a finished house, which drives cost up significantly.
Replacing a duct system that’s beyond repair. Flex duct that’s been in an unconditioned attic for 25+ years may have degraded beyond what sealing can fix: collapsed sleeves, crumbling insulation, disconnected connections throughout. At that point, partial fixes become more expensive than starting over.
Major renovations that change the home’s layout. Adding a room, removing walls, or converting an attic can make the existing duct system obsolete or unable to serve the new configuration.
Completing a heat pump or AC installation in a home with only a boiler system. The equipment alone is worthless without the air distribution network.
Sheet metal vs. flex duct
This is the most consequential material decision in a ductwork installation.
Sheet metal (galvanized steel or aluminum) is the original standard. It’s rigid, durable, and maintains its shape indefinitely. Long trunk lines in sheet metal hold consistent airflow with minimal pressure drop. Properly sealed sheet metal can last 30+ years. The downside is cost and labor: sheet metal requires skilled fabrication and more installation time.
Flexible duct (flex duct) is an insulated plastic sleeve around a wire coil. It’s cheaper to buy, faster to install, and can navigate around obstacles without cutting and joining rigid sections. A properly installed flex run with gradual bends and tight connections performs adequately. The problem is that flex duct is easy to install badly: too many sharp bends, sagging between supports, connections that loosen over time. A kinked flex run can lose 50–60% of its designed airflow.
The practical recommendation: use sheet metal for trunk lines (the large main runs from the air handler) and flex duct for short branch runs to individual registers. A system that cuts costs by using flex duct throughout including long trunk runs is a system that will underperform.
Insulation requirements
All ductwork in unconditioned spaces (attics, crawlspaces, unconditioned basements) must be insulated. Current IECC requirements call for R-6 in most climates, R-8 in hot climates, for attic duct runs. Uninsulated ducts in a hot attic can lose 20–30% of cooling capacity to conduction before the air reaches a register.
Ask every contractor: “What R-value insulation are you installing, and does it meet current code for my climate zone?” An answer of “standard insulation” without a value number is not an answer.
Permits
Ductwork installation requires a permit in most U.S. jurisdictions. The permit triggers an inspection that verifies proper sizing, material, insulation, and sealing. Unpermitted duct work is a liability at home sale and may void the HVAC equipment warranty if the system fails due to installation issues.
A contractor who suggests skipping the permit to “save money” is telling you something about how they approach the rest of the job.
What a fair ductwork bid includes
A complete ductwork installation bid should itemize:
- Material type and grade (sheet metal trunk, flex branch, or all flex with justification)
- Insulation R-value for unconditioned runs
- Sealing method (mastic sealant and foil tape at all joints, not duct tape)
- Permit (included in price, contractor pulls it)
- Duct leakage test before and after (this is how you verify the work performed)
- Register and grille quantity and type
- Labor as a separate line or per-run breakdown
For the per-job questions to ask before signing, see The HVAC Quote Checklist.
What comes next
If you’re replacing existing ductwork rather than installing new, see ductwork replacement cost. If your ducts are structurally intact but leaking, sealing may be the better option — see duct sealing cost and options. For the diagnostic question of whether your ducts are actually the problem, start with how ductwork works.
