Updated April 2026
Ductwork Installation Cost for Central Air: With vs Without Existing Ducts
Ductwork is the single biggest cost variable in a central air project. Homes with good existing ducts pay the base equipment and labour price. Homes with no ducts pay $3,000-$10,000 more. This guide covers every scenario with specific numbers.
Quick Answer
New ductwork for central air costs $3,000-$10,000 depending on home size and complexity. Repairing existing ducts costs $500-$2,000. Homes with good existing ducts pay $0 extra for ductwork.
Three Ductwork Scenarios
Which scenario matches your home determines most of your total project cost.
Good existing ductwork
Added ductwork cost
$0
Total project cost
$4,000-$8,000
Signs this is your situation:
- ✓Ducts installed within last 10 years
- ✓No visible damage or disconnected sections
- ✓Home cools evenly from existing forced-air heat
- ✓Energy bills have been stable
Note: Have ducts inspected and pressure-tested before assuming they are fine. Typical inspection cost: $150-$300.
Existing ducts need repair
Added ductwork cost
$500-$2,500
Total project cost
$5,500-$10,500
Signs this is your situation:
- ✓Ducts are 15+ years old
- ✓Some rooms consistently warmer than others
- ✓Visible gaps, sags, or disconnected flex duct
- ✓Energy bills have increased in last 3-5 years
Note: Duct sealing with mastic or foil tape recovers 20-30% of lost cooling. Often worth doing even if you are not replacing the AC unit.
No existing ductwork
Added ductwork cost
$3,000-$10,000
Total project cost
$10,000-$17,000
Signs this is your situation:
- ✓Home was heated with radiators or baseboard heat
- ✓Home uses window air conditioners for cooling
- ✓No central vents or return air grilles visible
- ✓Boiler or radiant floor heating system
Note: If ductwork cost would exceed $7,000-$8,000, get mini-split quotes too. See the mini-split vs central air comparison.
Ductwork Cost by Home Size
Full new ductwork installation cost, including trunk lines, branches, supply registers, return grilles, insulation, and labour.
| Home Size | Supply Runs (typical) | New Ductwork Cost | Labour (hrs) | Total w/ AC System |
|---|---|---|---|---|
| 1,000 sq ft | 6-8 | $2,500-$4,500 | 12-18 | $7,000-$10,000 |
| 1,500 sq ft | 8-10 | $3,000-$5,500 | 16-22 | $8,500-$12,000 |
| 2,000 sq ft | 10-12 | $4,000-$7,000 | 20-30 | $10,000-$14,500 |
| 2,500 sq ft | 12-15 | $5,000-$8,500 | 25-35 | $12,000-$17,000 |
| 3,000 sq ft | 14-18 | $6,000-$9,500 | 30-40 | $13,500-$19,000 |
| 3,500+ sq ft | 18-24 | $7,500-$12,000 | 38-50 | $16,000-$24,000 |
Duct Material Comparison
The type of ductwork material affects cost, durability, and long-term efficiency.
| Material | Cost per Linear Foot | Lifespan | Pros | Cons |
|---|---|---|---|---|
| Sheet metal (galvanized) | $7-$13 | 40+ years | Most durable, best airflow, low leakage | Higher cost, harder to install in tight spaces |
| Flexible duct | $1-$3 | 15-25 years | Cheap, easy installation, good for branches | Kinks reduce airflow, degrades faster, leaks more |
| Fibreboard | $3-$6 | 15-20 years | Good insulation, quieter than metal | Can grow mould if wet, not recommended for humid climates |
Recommended approach: Sheet metal trunk lines from the air handler to main distribution points, with flexible duct branches running to individual room registers. This combines the durability of metal with the installation flexibility of flex duct.
What Is Included in Ductwork Installation
Main trunk line
$800-$2,000
The central duct that runs from the air handler. Sheet metal, 12-20 inch diameter.
Branch supply runs
$200-$500 each
Individual runs from trunk to each room register. Usually 6-8 inch diameter flex duct.
Supply registers
$20-$80 each
The vents in floors, walls, or ceilings where cold air enters rooms.
Return air grilles
$40-$150 each
Large grilles (usually in hallways) that pull air back to the air handler.
Return air plenum
$300-$800
The box connecting return grilles to the air handler.
Duct insulation
$500-$1,500
Required in unconditioned spaces (attic, crawl space) to prevent heat gain/loss.
Sealing and tape
$150-$400
Mastic or foil tape to seal all joints. Reduces air leakage and energy waste.
Hangers and supports
$100-$300
Metal hangers and straps to support ductwork in framing cavities.
Duct Repair vs Replacement: Decision Guide
| Repair Type | Cost Range | Best When |
|---|---|---|
| Duct sealing (mastic) | $300-$1,000 | Joints are leaking but ducts are otherwise structurally sound |
| Aeroseal duct sealing | $1,500-$4,000 | Ducts are in walls/ceilings and impossible to access manually |
| Duct insulation addition | $800-$2,000 | Ducts run through unconditioned attic or crawl space |
| Partial duct replacement | $1,000-$3,500 | One or two damaged sections; rest of system in good shape |
| Full duct replacement | $3,000-$10,000 | System is 20+ years old, extensive damage, or original system was poorly designed |
Rule of thumb: If more than 30-40% of your duct system needs work, full replacement is usually more cost-effective than piecemeal repairs. Get quotes for both and compare.
When to Choose Mini-Splits Instead
If new ductwork is required, mini-split systems become cost-competitive or even cheaper:
Central Air + Ductwork Wins When:
- ✓Ductwork cost is under $4,000
- ✓Home is 2,000+ sq ft (economies of scale)
- ✓You want invisible vents (no wall units)
- ✓Central air adds more resale value in your market
Mini-Splits Win When:
- ✓New ductwork would cost $7,000+
- ✓You only need to cool 1-4 rooms
- ✓Home has historic or architectural limitations on ductwork
- ✓You want zoned temperature control
Full comparison: Mini-Split vs Central Air cost guide →
Frequently Asked Questions
How much does ductwork cost for a new central air system?
New ductwork for central air costs $3,000-$10,000 for a typical home depending on size and complexity. A 1,500 sq ft single-story home runs $3,000-$5,500. A 2,500 sq ft two-story home runs $5,500-$9,000. Attic or crawl space installations cost more due to difficult access.
Can I install central air without adding ductwork?
Yes. Ductless mini-split systems provide central-air-level cooling without any ductwork. A single-zone mini-split for one room costs $2,000-$4,000. A whole-home multi-zone mini-split system costs $8,000-$16,000. If your ductwork cost estimate exceeds $7,000, mini-splits often become the better value.
How much does it cost to repair existing ductwork?
Duct sealing costs $300-$1,000 for a typical home. Adding or replacing duct insulation costs $800-$2,000. Partial duct replacement (one or two runs) costs $1,000-$3,500. Full duct replacement is cost-effective when more than 30-40% of the system needs work.
What type of ductwork is best for central air?
Sheet metal (galvanized steel) is the gold standard: most durable (40+ years), best airflow, lowest leakage rates. Flexible duct is cheaper and easier to install in tight spaces but degrades faster and kinks easily. For new central air installation, specify sheet metal trunk lines with flexible branches to registers.
How long does ductwork installation take?
New ductwork for a 1,500-2,000 sq ft home takes 2-3 days for a 2-person crew. A 3,000 sq ft two-story home with difficult access takes 3-5 days. Duct repair and sealing typically takes 4-8 hours. The permit inspection happens 1-3 days after completion.