Duct Repair & Sealing Cost - Leakage Measured, Then Priced in Writing

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How Much Does Duct Repair & Sealing Cost in Pasadena?

Duct repair and sealing in Pasadena typically costs between $350 and $1,900, with most homeowners paying around $850 to $1,200 for a full sealing job on an average 1,800 to 2,400 square foot home. Minor repairs, like sealing a single visible gap or reconnecting a separated duct run, start around $150 to $400. The final number depends on how much of your ductwork is accessible, how many leaks or disconnects the technician finds, and whether sections of duct need replacing outright.

At Hollis Air Duct Pasadena, we give you the price in writing before we touch anything. You’ll know the number before work starts, and that number does not move at the door. If you want a firm quote for your specific house in Pasadena, call (626) 469-5477 and we’ll schedule a walkthrough.

Duct Repair & Sealing Cost Breakdown (2026)

Here is what duct repair and sealing work costs in the Pasadena market as of 2026. These are real working ranges based on what we quote and see day to day across Altadena, South Pasadena, San Marino, Sierra Madre, and the neighborhoods around the Rose Bowl.

That last row matters in Pasadena. If your ducts have been leaking for years, the insides are carrying dust, construction debris, and possibly rodent nesting from older foothill homes. Sealing a dirty system locks the problem in. We usually recommend cleaning first, sealing second, so the mastic bonds to clean metal and the system actually stays airtight after the job.

What Affects Duct Repair & Sealing Pricing in Pasadena

Two houses on the same street can have very different duct repair bills. Here is what actually moves the number.

• Attic vs. crawl space access. Pasadena runs the gamut: bungalows with tight crawl spaces, two-story Colonials with steep attic stairs, mid-century homes with flat roofs and low clearance. Crawl space work usually adds 15 – 25% to labor because technicians are working on their backs in tight quarters. Attic work in the summer adds heat stress to the crew, which we factor into scheduling but not into games with the price.
• How much of the ductwork is exposed. The more duct you can physically see and reach, the cheaper the sealing job. Finished basements, dropped ceilings, or drywalled soffits that hide duct runs force us to cut access panels, and that adds time and materials.
• Number of actual leaks. A house in the Historic Highlands with original 1960s sheet metal might have 12 – 20 joints leaking. A newer tract home in Hastings Ranch might have two or three. We find the leaks with a pressure test and show you where they are before we quote the fix.
• Duct material and age. Older rigid sheet metal ducts seal beautifully with mastic and last another 20 to 30 years. Cheap flex duct from a 1990s addition in foothill neighborhoods like Linda Vista tends to sag, tear at connection collars, and often needs replacing rather than sealing.
• Pest damage. Rats and mice love the attic spaces in Pasadena’s older neighborhoods, especially near the Arroyo Seco. Rodent damage to flex duct or insulation means patching is not enough; sections need removal and replacement. We’ve seen it in Altadena, Bungalow Heaven, and the San Rafael hills.
• Whether the system was disturbed by previous work. Furnace replacement, attic insulation, pest control fogging, even roofers moving ducts to reach flashing can leave joints disconnected. If a section was pulled off a boot, reconnecting and sealing is straightforward. If the duct tore at the seam, it may need replacement.

How Much Does Duct Sealing Save on Energy Bills in Pasadena?

This is the question behind the question, and it deserves numbers. Leaky ducts in a typical Pasadena home waste 20 – 30% of the air your furnace or AC produces. That air is being paid for. It’s conditioned, pushed through the system, and dumped into the attic or crawl space instead of your living room.

For a home running central air through Pasadena’s summer months, with SCE electricity rates pushing north of $0.30 per kWh during peak hours, a 20 – 30% system loss translates to roughly $250 to $500 per year in wasted energy. A $1,000 duct sealing job pays for itself in two to four years, faster if you run the AC from June through October, which is standard for the San Gabriel Valley.

Beyond the utility bill, sealed ducts pull fewer particulates from the attic into the living space. Attics in Pasadena are dusty places, and a leak on the return side draws that dust straight into the system and through your filter. Tightening the return side means the filter does its job on outside air, not re-filtering attic debris.

Signs You Need Duct Repair or Sealing

Not every house in Pasadena has obvious duct leaks. Here is what we see and what we tell homeowners to check before they call.

• Rooms that never cool down or heat up. If one bedroom in a Spanish Colonial near Caltech stays five degrees hotter than the rest of the house during summer, the duct run feeding that room is either disconnected, crushed, or leaking badly.
• Dust accumulation right after cleaning. You dust on Saturday and by Wednesday the surfaces have a film again. That is often return-side leaks pulling attic dust into the system and distributing it through every supply register.
• Higher Pasadena Water and Power or SCE bills than recent years, without a change in how you use the house. If the system runs longer to hit the same thermostat setting, something is wrong. Leaky ducts are the most common culprit we find.
• Whistling or rattling near registers. Joints that have come apart allow air to escape under pressure, and the sound carries through the metal. Rattling is often a disconnected boot or a loose damper.
• Attic smells that come through the vents. Musty or dusty odors from the vent registers when the fan kicks on mean the return side is pulling attic air. In older Pasadena homes with wood shake roofs, that air carries fine dust and sometimes old insulation fibers.
• Heat pump or AC running constantly during mild weather. If the system runs 10 – 12 hours a day during a mild April or November week, it is fighting itself. Sealed ducts reduce the load enough that we usually see run times drop within the first billing cycle after the work.

The Hollis Approach: Written Price Before Work Starts

Here is how a duct repair job with Hollis Air Duct Pasadena works, start to finish. No surprises, no moving numbers.

Step one: the walkthrough. We come to your home in Pasadena, find the furnace or air handler, open the access points, and inspect the duct system. We look at the plenum, the visible runs, the boots at the registers, and the return path. If we suspect leaks we cannot see, we run a pressure test or use a smoke pencil on the main joints. You’re welcome to watch.

Step two: the written quote. We hand you a price on paper before any work begins. That number includes labor, materials, and any access cutouts we need to make. If something changes, you approve the change before we proceed. The price does not balloon at the door.

Step three: the work. Our technicians are background-checked and uniformed. They work under The Garrison Standard, which means arriving inside the quoted window, doing the job by the book, and leaving the site clean. No drop cloths balled up in the corner, no mastic fingerprints on the wall.

Step four: the 365-Day Done Right Promise. Every duct repair and sealing job at Hollis is covered in writing for a full year. If a sealed joint fails or a repaired section comes apart during that year, we come back at no charge. That includes a free second visit. Not negotiated. Not prorated. Written down.

This is the difference between Hollis and a lot of the Pasadena duct trade. We are part of the Garrison Partners family and have been doing this work since 2004. The standard was not invented last month by a franchise marketing team. It has been the operating rule for two decades.

Duct Sealing Methods We Use

The trade has real words for this work, and you should know them when you compare quotes from Pasadena contractors.

Mastic Sealing

Mastic is a thick, brush-on sealant that hardens into a permanent, rubber-like seal over duct joints, seams, and connections. This is the method required by California energy codes for new duct systems, and it is the standard we apply on repair work. Unlike tape, mastic does not dry out, peel, or lose adhesion over time when applied correctly. It is the correct material for the job, which is why Code Title 24 in California specifically requires mastic for duct sealing in new construction and major alterations.

Foil Tape (UL 181 rated)

For small, accessible gaps and temporary patches, UL 181-rated foil tape works. However, we use it only where mastic is not practical, like hand-access spots where a brush cannot reach. Regular duct tape, the gray cloth kind from the hardware store, is not rated for HVAC use and fails within a year or two in a hot Pasadena attic. If a contractor shows up with gray cloth tape, that is a red flag.

Aeroseal (Aerosol Duct Sealing)

Aerosol sealing systems inject a mist of sealant into the ductwork under pressure. The particles collect at leaks and build up until the gap is sealed. This works well for ducts hidden inside walls where manual access is impossible. It is more expensive than manual mastic sealing but can be the right call in older Pasadena homes where significant portions of the ductwork run through inaccessible chases. We can assess whether your home is a candidate.

Pairing Sealing with Cleaning

Sealing dirty ducts is like painting over peeling paint. If the inside of the duct is coated with years of dust, the sealant bonds to the dust layer instead of the metal, and the seal fails early. We recommend a cleaning pass first when the system is heavily soiled. Our equipment includes Rotobrush rotary brush systems and Nikro negative-air machines, which scrub and capture debris rather than blowing it through the home. Then we seal clean metal-to-metal joints so the work holds.

How to Save on Duct Repair & Sealing in Pasadena

The most expensive duct repair is the one you redo because someone cut corners the first time. Here is how to get the work done once and not pay for it twice.

• Bundle cleaning and sealing. If your ducts are dirty and leaky, doing both in one visit saves a trip charge and reduces the total labor hours. We quote this as a combined number, which is usually 15 – 20% less than booking the two services separately.
• Seal the whole system at once, not one leak at a time. If we find five leaks today, there will be five more next year. Sealing every accessible joint in one session costs more on the front end but eliminates the recurring call-out fees that piecemeal repairs add up to.
• Check your attic insulation before winter. If you are having insulation blown in, have the ductwork repaired and sealed first. Once the ducts are buried under new insulation, finding and fixing leaks becomes far more expensive.
• Ask for the pressure test results. A contractor who tests before and after can show you the improvement. We include static pressure readings on every full sealing job, so you know the work did something measurable rather than taking our word for it.
• Use the free estimate. Our walkthrough and written quote cost nothing. Call (626) 469-5477, get a number in writing, and compare it against any other Pasadena duct company. If our number is higher, ask the other contractor whether their quote includes mastic sealing, a pressure test, and a one-year written guarantee. Often the comparison is not apples to apples.

Why Pasadena Homes Specifically Need Duct Attention

Pasadena is not one housing market; it is a hundred neighborhoods built across a century of different construction standards. That affects ductwork directly.

Homes in Bungalow Heaven and the Historic Highlands, many built between 1910 and 1940, have been retrofitted with central air over the decades. Duct systems in these homes are often patchworks: original gravity-furnace chases repurposed, flex duct added to additions, returns pulled through wall cavities. The connection points between different materials leak. We find more failed joints in these older homes than anywhere else in Pasadena.

Mid-century homes in Hastings Ranch and Linda Vista often have slab foundations with ducts running through the slab or through shallow attics. Slab ducts are harder to access, and when they fail, the repairs are more involved. Attic ducts in these homes bake in the summer heat, which accelerates tape failure and makes flexible duct brittle.

Newer construction in the Arroyo Seco area and east Pasadena generally meets California Title 24 sealing requirements from the start. But even new systems settle. The first year of operation is when we see boot connections loosen and new duct runs shift. A quick sealing pass in year two or three can prevent a decade of slow leaks.

Then there is the geographic reality: Pasadena sits in a valley that traps summer heat, and our air conditioners work hard from June through October. Every percentage point of duct leakage is a percentage point of cooling you paid for and never felt. This is not an abstract energy problem; it shows up right on the July and August bills from Pasadena Water and Power.

FAQs – Duct Repair & Sealing Cost in Pasadena

How much does duct sealing cost per square foot in Pasadena?

Duct sealing in Pasadena typically runs $0.35 to $0.70 per square foot of home space for a full system seal, meaning a 2,000 square foot home lands in the $700 to $1,400 range. Homes with slab ductwork or heavy pest damage fall on the higher end. Call (626) 469-5477 for a written, exact quote; the estimate is free.

Is it cheaper to repair or replace ducts?

Repair is almost always cheaper. Repairing and sealing accessible ductwork costs $700 to $1,400 on average in Pasadena, while a full duct replacement runs $3,500 to $8,000 or more. Most homes only need replacement when ducts are collapsed, rodent-damaged beyond repair, or incorrectly sized from day one. We will show you the damage before recommending replacement.

How long does duct sealing last?

Proper mastic sealing on clean metal ductwork lasts 15 to 20 years or longer in Pasadena conditions, which is why we clean before sealing when needed and use mastic rather than tape. Our work is covered by the 365-Day Done Right Promise in writing; if a seal fails within a year, we return at no charge.

Can you come repair a duct today?

We answer the phone with a live person 24/7, and same-week scheduling is standard during most of the year. Same-day service depends on crew availability and job size. Call (626) 469-5477 and we will tell you the soonest window, commit to it in writing, and show up inside it. That is part of The Garrison Standard.

Does homeowners insurance cover duct repair in Pasadena?

Most standard policies do not cover duct repair from normal wear, aging, or poor installation. Damage from covered events, like a fire or a tree falling through the roof, may be covered. Some policies exclude rodent damage. The safest path is to call us for a documented inspection and written cost breakdown, then submit it to your insurer and let them make the call.

How do I know if my ducts need sealing or just cleaning?

If rooms are unevenly heated, your energy bills have climbed, and you see dust appearing days after cleaning, the answer is likely both: the leaks pull attic dust in, and the cleaning removes what accumulated. We inspect first, show you the findings, and recommend cleaning, sealing, or both based on what we measured. Our full Duct Repair & Sealing service page walks through what a typical inspection covers.

Get a Written, No-Pressure Quote in Pasadena

You will not get a teaser price from us and a bigger number at the door. You will get a technician who shows up uniformed, on time, ready to inspect your duct system and explain what they find in plain English. Then you will get a written price. You decide. The pressure stops there.

Call (626) 469-5477 to schedule a free duct inspection and written quote in Pasadena, Altadena, South Pasadena, San Marino, or the surrounding San Gabriel Valley. We answer the phone live. The estimate costs nothing. The 365-Day Done Right Promise covers the work for a full year, in writing. That is how we have done business since 2004.

Written by Roy Castellanos, Owner at Hollis Air Duct Pasadena, serving Pasadena and the San Gabriel Valley since 2004.

Pricing reflects the Pasadena market as of 2026. Hollis Air Duct Pasadena offers free estimates – call (626) 469-5477.