Ductwork Installation Cost

Replacing your home's ductwork costs a 2026 US range of $1,400–$5,600 for a full system, roughly $25–$55 per linear foot or $270–$500 per duct run. That range covers the three levers that move every quote: how many feet of duct your home needs, what material the crew installs, and how hard the runs are to reach. Ducts are the delivery system your equipment breathes through — and when they're leaky, crushed, or wrongly sized, they waste 20–30% of your conditioned air, which is why ductwork is almost always replaced alongside the AC system or furnace it serves. A replacement typically cuts heating and cooling bills 10–40%, so the project often pays for itself while the new equipment is still young.

Ductwork cost by home size

The fastest way to sanity-check a quote is the home-size band. Bigger homes need more runs, longer trunks, and usually more zones — and multi-story homes need 20–30% more linear footage than a single-story home of the same square footage, because ducts have to travel between floors.

Contractors estimate the footage with a rough rule: about 1 linear foot of duct per 8–10 sq ft of conditioned space for a single-story home, plus 20–30% for multi-story. So a 2,000 sq ft ranch is in the neighborhood of 200–250 linear feet of duct — at $25–$55/LF installed, that's exactly the $2,800–$5,600 band above. If a quote lands far outside these bands, ask what's driving it: access problems, material upgrades, or scope differences like added returns and zoning.

Cost per linear foot and per run

Most contractors price ductwork one of two ways — by the linear foot of installed duct, or by the duct run (one branch from the trunk to a register). Both numbers should appear on a detailed quote so you can compare bids apples to apples.

Line items that ride along with the footage: old duct removal $200–$800, registers and boots $10–$40 each, insulation wrap as an add-on $0.50–$1.50 per linear foot, and a mechanical permit $50–$400 depending on your municipality. Get each of these as its own line on the quote — a single lump sum hides the material-versus-labor split and makes bid comparison guesswork.

Material comparison: flex vs. duct board vs. sheet metal

Material choice is the single biggest price lever after footage, and it's also a lifespan decision you'll live with for decades. Here's how the three common residential options stack up:

The cheap-material trap is real: flexible duct at $20–$35/LF looks like a bargain until you're replacing it again in 12 years while the sheet metal system at $45–$60/LF is still going strong at year 40. For a forever home, sheet metal's lifetime cost per year is usually the lowest. For a home you'll sell in five years, quality flex with gentle bends and proper supports is a defensible budget choice — and it still beats limping along on crushed, leaking original ducts.

Where the ducts run changes the price

Access is the hidden multiplier. The same footage costs far more to install in a 120°F attic with a 3-foot crawl than in an open basement where a crew can stand upright and reach every joint.

Inside-wall runs are the budget killer because you're paying for two trades: the HVAC crew and the drywall repair after. When a contractor proposes routing through finished walls, ask whether an attic or soffit route gets the same result without the patching bill — it often does.

How ductwork is installed, step by step

A proper installation follows the industry standards contractors use for load math, duct sizing, and equipment selection — Manual J (how much heating and cooling each room needs), Manual D (how big each duct must be to deliver it), and Manual S (matching the equipment to both). You don't need to do this math, but you should expect your contractor to — a quote with no sizing discussion is a red flag. The process:

• Load calculation (Manual J): the contractor measures your home and calculates each room's heating and cooling load — not just square footage, but windows, insulation, and orientation. This decides how much air every room needs.
• Duct sizing (Manual D): each trunk and branch is sized to carry its room's airflow at the right velocity. Undersized ducts whistle and starve rooms; oversized ones cost more and deliver lazy, uneven airflow.
• Equipment match (Manual S): the furnace or AC is selected to fit the ducts and the load — an oversized unit short-cycles and never dehumidifies properly.
• Layout and fabrication: trunks run along the shortest sensible path; sheet metal is fabricated, flex is cut to length with gentle curves, and every run gets proper supports (flex should never sag between joists).
• Sealing with mastic: every joint, seam, and boot connection gets sealed with duct mastic — the thick paint-on sealant — not just tape. Foil tape alone fails within a few years; mastic lasts.
• Insulation: any duct in an attic, crawlspace, or garage gets wrapped to at least R-6 (R-8 in many climates) so the air doesn't lose its temperature before it reaches the room.
• Leakage testing: the finished system is pressure-tested (a duct blaster test) to verify leakage is within target — typically under 5–10% of system airflow. Ask for the test report; a contractor who won't test is a contractor guessing.

A full-home replacement usually takes 2–4 days for a typical single-story home and up to a week for large multi-zone systems. If you're pairing it with new equipment, budget the two together — our heat pump installation cost guide covers ducted conversions, where existing ducts often need resizing to match the new system's airflow.

Duct repair vs. full replacement

Not every tired duct system needs a full tear-out. Repairs make sense when the damage is localized and the system is otherwise within its lifespan:

• Partial repair: $1,000–$4,000 — sealing accessible joints with mastic, replacing a crushed or disconnected run, re-insulating exposed sections.
• Adding 1–3 return runs: $1,500–$4,500 — many older homes are return-starved, which causes pressure imbalances, slamming doors, and rooms that won't cool. Adding returns is one of the highest-value upgrades you can make.
• Sealing existing ducts yourself: homeowner-legal in most areas — mastic on accessible joints plus insulation wrap can recover a large share of lost airflow for the cost of materials.

Go full replacement when the system is past its material lifespan (15+ years for flex, 25+ for duct board), when leaks are everywhere rather than in one spot, or when the ducts are fundamentally the wrong size for your home. The decision rule contractors use: if the repair quote passes 40–50% of replacement cost, replace. You get a designed system, a leakage test, and decades of life instead of another round of patching.

Costly mistakes to avoid

• Oversized flex with tight bends. Flex duct choked around a tight corner can lose half its rated airflow. Every bend should be a gentle sweep, pulled taut — a 25-foot run doing the work of 15 feet is money thrown away.
• Skipping the Manual D sizing. “Same size as the old ducts” is how the old problems get reinstalled. The old system's hot and cold spots were often a sizing problem, not an equipment problem.
• Sealing with tape instead of mastic. Standard duct tape dries out and peels within a few years. Mastic at every joint, or don't bother — a leaky new system is the most expensive kind.
• Forgetting the returns. Homeowners focus on supply registers, but undersized or missing return air is behind a huge share of comfort complaints. If your quote has no return-air plan, it's incomplete.
• Not getting a leakage test. A duct blaster test is the only proof the system performs as designed. Verbal “we sealed everything” is not a test report.
• Replacing equipment but keeping bad ducts. A new high-efficiency furnace or AC on crushed, leaky ducts performs like the old unit did. Ducts and equipment are one system — budget them together, starting with the HVAC BTU calculator to right-size the equipment side.

DIY vs. hiring a pro

Full ductwork installation is pro work. Sizing a system requires room-by-room load math, duct fabrication or precise flex layout, and leakage testing — get any of it wrong and you've bought an expensive set of new problems. Licensed contractors also handle the mechanical permit and the final inspection, which matters for insurance and resale.

What's firmly in the homeowner lane: sealing and insulating existing ducts. Painting mastic onto accessible joints in your attic or basement, re-hanging sagging flex, and wrapping bare runs in insulation wrap are legal in most places, cost a fraction of a replacement, and can recover a big share of the 20–30% of conditioned air that leaky ducts waste. Do that first — then get quotes for a full replacement only if comfort problems persist.

Do you need a permit?

Yes, in most municipalities — ductwork replacement typically requires a mechanical permit costing $50–$400, with an inspection at completion. The permit is cheap insurance: the inspector verifies clearances, supports, and sealing that you can't easily check yourself once the attic hatch closes. Any contractor who suggests skipping the permit is telling you something about how they work — check your municipality's requirements before the crew arrives, and make sure the permit (and who pulls it) is named in the contract.

Start by sizing the equipment side correctly with the HVAC BTU calculator, then get three quotes that each include footage, material, a Manual D sizing statement, and a leakage test. When the quotes are in, send them through CalcBid's quote tool to compare line by line — the cheapest bid is rarely the one with the mastic, the test report, and the right-sized returns.