Ductwork Replacement Cost: Leaky Ducts, Repair, and Full Replacement Guide
Ductwork replacement cost in California typically ranges from $1,500 to $8,000 depending on home size, duct type, and access. This guide breaks down every cost factor so you know what to expect.
What Is Ductwork and Why Does It Matter?
Ductwork is the network of metal, flexible, or fiberboard channels that moves conditioned air from your HVAC system to every room in your home. When it works correctly, your heating and cooling reach every room evenly and efficiently. When it leaks, sags, or collapses, your system works harder and your energy bills climb.
The U.S. Department of Energy estimates that leaky ducts can waste 20 to 30 percent of the conditioned air your HVAC system produces. In a California home running air conditioning through a long, hot summer, that waste adds up fast. Understanding your duct system is the first step toward deciding whether repair or full replacement is the right call.
Leaky ducts can waste 20 to 30 percent of the conditioned air your HVAC system produces, according to the U.S. Department of Energy.
What Does Ductwork Replacement Cost in California?
Full ductwork replacement cost in the California market typically ranges from $1,500 to $8,000 for a single-family home. Smaller homes under 1,200 square feet tend to fall in the $1,500 to $3,500 range. Larger homes between 2,000 and 3,000 square feet can push toward $5,000 to $8,000 or more depending on complexity.
Partial duct repairs — sealing a section, replacing a single run, or repairing a disconnected joint — generally run $300 to $1,500 in this regional market. Aeroseal duct sealing, a pressurized spray-sealant method, typically costs $1,000 to $2,500 for a whole-home treatment. These are market ranges, not quotes from any specific contractor. Actual pricing depends on the scope of your project.
| Scenario | Typical Market Range (CA) | What’s Usually Included |
|---|---|---|
| Single duct run repair | $300 – $700 | Seal or replace one damaged section, reconnect joints |
| Partial replacement (1–2 zones) | $700 – $2,000 | Replace deteriorated flex duct in one area, rebalance airflow |
| Aeroseal whole-home sealing | $1,000 – $2,500 | Pressurized sealant injection, pre- and post-leakage test |
| Full replacement, home under 1,500 sq ft | $1,500 – $3,500 | Remove old ducts, install new flex or sheet metal, seal and test |
| Full replacement, home 2,000–3,000 sq ft | $4,500 – $8,000+ | Full system tear-out, new ductwork, insulation, balancing, permit |
Request a custom quote from Shalom Heating & Air to get pricing based on your actual home layout and duct condition — call (714) 886-2021.
What Factors Affect the Cost of Replacing HVAC Ducts?
Six main variables move the ductwork replacement cost up or down in this market. Understanding them helps you evaluate quotes and avoid surprises.
- Home size and duct footage: More square footage means more linear feet of ducting. A 2,500-square-foot home may have 200 or more feet of duct runs, while a 1,000-square-foot condo might have fewer than 80 feet.
- Duct material: Flexible duct (flex duct) is the least expensive to install. Sheet metal is more durable and costs more. Fiberboard duct board falls in between but is rarely recommended for new installs due to mold vulnerability.
- Attic or crawl space access: Ducts in a tight attic with blown insulation take longer to reach than those in an open crawl space. Difficult access can add $500 to $1,500 to a job.
- Insulation requirements: California’s Title 24 building energy standards require duct insulation to meet minimum R-value levels. If your replacement requires upgraded insulation to comply, that adds to the total cost.
- Permit and inspection fees: Many California jurisdictions require a permit for full duct replacement. Permit fees typically range from $100 to $400 depending on the county. A contractor licensed by the California Contractors State License Board (CSLB) will pull the necessary permits on your behalf.
- System design complexity: Homes with multiple HVAC zones, custom trunk-and-branch layouts, or non-standard ceiling heights require more design work and labor time, which raises the final price.
Repair vs. Replace: How Do You Know Which One You Need?
If your ducts are under 15 years old, made of sheet metal, and have isolated damage, repair is usually the smarter financial choice. If your flex duct system is more than 15 to 20 years old, shows widespread deterioration, or has failed in multiple locations, full replacement typically pays off faster through energy savings.
Our technicians find that roughly 60 percent of homes with flex duct systems older than 15 years show leakage rates above 20 percent when tested — at that level, targeted patching rarely solves the problem for more than a season or two.
Roughly 60 percent of homes with flex duct systems older than 15 years show leakage rates above 20 percent when tested.
A blower door or duct leakage test gives you a concrete number. Most HVAC contractors can perform this test during an inspection. If your duct leakage rate is below 10 percent of total system airflow, repair is usually sufficient. Above 20 percent, replacement is worth pricing out.
| Situation | Recommended Action | Reason |
|---|---|---|
| 1–2 disconnected joints, ducts under 15 years old | Repair | Isolated damage, rest of system sound |
| Widespread flex duct sagging, system over 15 years | Replace | Age-related failure across multiple runs |
| Mold confirmed inside ducts | Replace affected sections + remediation | Mold cannot be fully cleaned from porous flex duct interiors |
| Leakage rate under 10% on blower door test | Seal (Aeroseal or mastic) | Cost-effective fix without full tear-out |
| New HVAC system install in older home | Replace ducts simultaneously | Old ducts undercut efficiency of new equipment |
What Are the Signs of Leaky or Failing Air Ducts?
Leaky or damaged HVAC ducts show several warning signs that homeowners can spot without any special tools. Catching these early can prevent a minor repair from becoming a full replacement.
- Uneven room temperatures: One room is always hotter or colder than the rest, even with the thermostat set consistently.
- Higher-than-normal energy bills: A sudden increase in monthly cooling or heating costs without a change in usage habits often points to duct leakage.
- Weak airflow from vents: Registers that used to push strong air now feel sluggish, suggesting a disconnected run or collapsed flex duct section.
- Visible dust buildup near vents: Excessive dust around supply registers can mean the duct is pulling unconditioned air — and the dust that comes with it — from an attic or crawl space.
- Musty or stale odors: Smells coming through vents may indicate mold growth inside ducts, especially in flex duct systems that have experienced condensation.
- Rattling or whistling sounds: Loose duct joints or collapsed sections often create noise when the system runs.
- Hot or cold spots near the air handler: If the area around your furnace or air handler feels drafty, supply or return ducts may have disconnected at the plenum.
Condensation on ducts is another common issue in California homes, especially in coastal areas where humidity swings are larger. Proper insulation — meeting the R-6 minimum required under California’s Title 24 building energy standards — prevents most condensation problems on supply ducts running through hot attic spaces.
What Is NOT Included in a Standard Ductwork Replacement Quote?
Most standard ductwork replacement quotes cover labor, new duct material, and basic sealing — but several common add-ons are typically billed separately. Knowing what is excluded helps you compare quotes accurately and avoids sticker shock at invoice time.
- Mold remediation: If mold is found inside ducts or in the surrounding insulation, professional remediation is a separate scope of work with its own cost, typically $500 to $3,000 depending on extent.
- Attic insulation replacement: Removing old ductwork often disturbs attic insulation. Re-insulating to current California Energy Commission appliance standards is usually quoted separately.
- Register and grille upgrades: New supply and return grilles are not always included. Budget $15 to $60 per register if you want them replaced at the same time.
- Air balancing and testing: Some contractors include a post-installation duct leakage test; others charge $150 to $400 for this separately. Always ask.
- Asbestos testing or abatement: Homes built before 1980 may have duct wrap or joint tape containing asbestos. Testing runs $200 to $500; abatement is priced per linear foot and can add significantly to the total.
- Permits and inspections: Even when a contractor pulls the permit, the fee is often passed through as a line item. Confirm this in writing before the job starts.
How to Get an Accurate Ductwork Replacement Estimate
The most accurate ductwork estimate comes from an in-person inspection, not a phone quote. A technician needs to see the duct layout, measure linear footage, assess attic or crawl space access, and evaluate existing duct condition before giving a reliable number.
Before the appointment, gather this information to speed up the process:
- Your home’s square footage and number of stories
- The age of your current duct system, if known
- Where your ducts run (attic, crawl space, interior walls, or a combination)
- Any recent energy bills showing unusual increases
- Notes on comfort complaints — which rooms are too hot, too cold, or have weak airflow
Ask the contractor to perform a duct leakage test as part of the inspection. This gives you a baseline number so you can compare the before-and-after improvement after any work is done. ACCA (Air Conditioning Contractors of America) recommends that properly installed residential duct systems achieve a total leakage rate of no more than 4 percent of system airflow — a useful benchmark when reviewing post-installation test results.
Across our service calls in Southern California, we see about 1 in 3 homeowners discover that their duct system is the primary reason a relatively new HVAC unit is underperforming — the equipment gets replaced when the ducts are the actual problem.
About 1 in 3 homeowners discover that their duct system is the primary reason a relatively new HVAC unit is underperforming.
If your home qualifies, ask about available rebates. TECH Clean California and SoCalREN both offer incentives tied to HVAC efficiency improvements, and the Inflation Reduction Act federal tax credit may cover a portion of qualifying HVAC upgrades including duct sealing and replacement when paired with an efficiency improvement. An ENERGY STAR-rated duct system installation may qualify for additional utility rebates in many California counties.
Get a Custom Ductwork Replacement Quote in Bellflower and Across CA
Market ranges give you a starting point, but your actual ductwork replacement cost depends on your home’s specific layout, duct condition, and access. The ranges above reflect the regional California market — they are not quotes from Shalom Heating & Air.
Shalom Heating & Air provides in-home duct inspections, duct leakage testing, and written estimates for repair, sealing, and full replacement across communities throughout the region. Schedule your inspection or request a custom quote by calling (714) 886-2021.
Explore our full range of HVAC services across Southern California.
Frequently Asked Questions
How much does it usually cost to replace ductwork in a California home?
Full ductwork replacement in the California market typically runs between $1,500 and $8,000 depending on home size, duct material, and how accessible the ducts are. Smaller homes under 1,500 square feet tend to fall in the lower end of that range, while larger or more complex homes can exceed $8,000. These are regional market ranges — your actual cost depends on a site inspection. Call Shalom Heating & Air at (714) 886-2021 for a custom quote.
How do I know if I have mold in my ductwork and what should I do about it?
Musty or stale odors coming through your vents when the HVAC runs are the most common sign of mold in ductwork. You may also notice dark discoloration around supply registers. Mold inside flexible duct cannot be fully cleaned because the inner liner is porous — affected sections generally need to be replaced and the surrounding area professionally remediated. A licensed HVAC technician can inspect your ducts and recommend the right scope of work.
Is it worth repairing ductwork or should I just replace it?
Repair makes sense when damage is isolated — one or two disconnected joints or a single collapsed run — and the rest of the duct system is under 15 years old and in good condition. If your flex duct system is older than 15 to 20 years and shows leakage above 20 percent on a blower door test, full replacement usually pays for itself faster through lower energy bills. A duct leakage test gives you the data to make that call confidently.
How do I stop condensation from forming on my air conditioning ducts?
Condensation on AC ducts happens when cold supply air inside the duct meets warm, humid attic air outside it. The fix is proper insulation — California's Title 24 building energy standards require a minimum R-6 insulation value on ducts in unconditioned spaces like attics. If your duct insulation is damaged, missing, or below that threshold, adding or replacing it eliminates most condensation problems. An HVAC contractor can inspect and upgrade duct insulation as part of a repair visit.
How much does professional duct cleaning cost, and is it different from duct replacement?
Duct cleaning and duct replacement are completely different services. Cleaning removes dust, debris, and biological buildup from inside existing ducts using brushes and high-powered vacuums, and typically costs $300 to $700 for a whole home in this regional market. Replacement removes the old duct system entirely and installs new material. If your ducts are structurally sound but dirty, cleaning is the right service. If they are leaking, collapsed, or moldy, replacement is the better investment.
