Duct Sealing in Miami - Leakage Measured, Then Priced in Writing

Trusted Duct Sealing for Miami Homeowners

Duct sealing in Miami typically costs $450 to $1,400 for a full home, depending on the number of runs and accessibility of the ductwork. Most jobs are completed in a single day by a two-person crew from Hollis Air Duct Miami. We have been sealing and repairing ductwork since 2004, and our technicians arrive uniformed, background-checked, and ready to give you a written price before any work begins. Call (850) 660-3272 to schedule a walkthrough. We serve the entire Miami area, from Miami Gardens to Palmetto Bay, and every job carries our 365-Day Done Right Promise in writing.

Call (850) 660-3272

Leaky ducts are not a small problem in South Florida. The heat and humidity here force your AC to work harder than it would anywhere else in the state, and every leak in the ductwork is cooled air you paid for that never reaches a single room. Roy Castellanos and his crews see it every week on Duct Sealing - Miami jobs: supply runs that have pulled apart in an attic, return plenums that were never sealed correctly at install, and flex duct that has sagged and kinked over the years. The fix is not a guess. It is a systematic, measured process of finding the leaks, closing them with the right material, and verifying the result with a second look before we leave.

Key Takeaways

• Whole-home duct sealing in Miami typically costs $450 to $1,400, with the written price locked before work begins.
• Every Hollis Air Duct Miami job is covered by the 365-Day Done Right Promise, in writing, at no extra charge.
• We use mastic and UL-listed tapes plus negative-air verification, not hardware-store foil tape that fails in a Miami attic.
• Technicians are background-checked and uniformed, and a live person answers the phone 24 hours a day, 7 days a week.
• Free estimates include a full walkthrough of the accessible ductwork and a line-item price, not a vague range.

Duct Insulation

Duct Insulation is the thermal barrier that keeps the cool air inside your ductwork cold while it travels through a hot Miami attic. When insulation is missing, compressed, or soaked from condensation or a roof leak, the air inside the duct picks up heat before it ever reaches your vents. In a city where attic temperatures routinely hit 130 degrees between May and October, an uninsulated run can lose more than a third of its cooling capacity from the air handler to the register in the master bedroom. Hollis Air Duct Miami inspects insulation condition on every job, and we replace or wrap it as part of a full sealing service. Pricing for insulation wraps and replacement typically runs $300 to $1,100 depending on how many linear feet are compromised and whether the duct is accessible from the attic floor or buried under blown-in insulation.

Fiberglass and Reflective Wraps

Most Miami homes built before 2015 used R-4.2 or R-6 fiberglass duct wrap, and that material breaks down with age. In attics with trapped moisture, the wrap sags, separates at the seams, and leaves bare sheet metal exposed. We replace compromised fiberglass and upgrade where the attic layout calls for it to reflective bubble insulation, which holds up better in tight clearance spaces near roof trusses.

When Condensation Is the Culprit

A duct that sweats in a Miami attic is a duct with insulation failure, not a duct that is simply cold. The dew point in South Florida sits high for most of the year, and once the vapor barrier on the wrap fails, condensation forms inside the wrap and quietly rots the duct underneath. We identify these conditions with a moisture reading before we recommend replacement, so you are not paying for new insulation over a duct that is already compromised.

HVAC Duct Sealing

HVAC Duct Sealing is the process of closing every gap, crack, and failed connection along the entire duct run from the air handler to each supply register and back through the return side. A duct system in a Miami home averages between 15 and 40 accessible connection points, depending on the floor plan and how many supply runs are in the attic. Hollis Air Duct Miami seals all of them with water-based mastic and UL-listed tape on the seams, not on the interior surfaces. A full HVAC sealing job for a typical three-bedroom home in Doral or Aventura runs from $550 to $1,200 depending on the number of runs and the condition of the connections, and we also offer Duct Sealing in Miami Beach at comparable rates. We record what we find, show you photos of the before and after, and confirm the pressure difference with a smoke test on the accessible joints before we pack up.

Supply Plenum and Collar Work

The single largest leak in most Miami duct systems is where the supply runs tap into the main plenum. Builders in the early 2000s often attached collars with a few sheet metal screws and called it done. Ten years of vibration and thermal expansion later, that collar has backed out a quarter inch, and a quarter inch across ten collars is a hole the size of your fist. We remove, reset, and reseal every collar as a standard part of HVAC duct sealing.

Return Side Leaks Matter More Than You Think

A leak on the return side pulls hot attic air into the system before it ever crosses the coil. That means the AC thinks the house is hotter than it really is, runs longer, and still leaves certain rooms sticky. In neighborhoods like West Little River and Fountainebleau where ducts run through unconditioned crawl spaces, return leaks are the most common cause of high humidity complaints we diagnose, and our Duct Sealing in Miami Gardens addresses the same crawl-space leak patterns.

Duct Repair

Duct Repair is the hands-on correction of physical damage to ductwork: crushed flex runs, disconnected joints, torn insulation, separated trunk lines, and holes punched by rodents or careless attic work. Some of this work overlaps with sealing, but repair is about restoring the duct to a functional state first and closing the leaks second. Hollis Air Duct Miami repairs damaged duct sections with the same professional-grade materials used by the commercial crews, including flex duct, rigid fittings, and water-based mastic from suppliers like Guardsman. Repairs in Miami typically range from $150 for a single reconnection to $900 or more for a full trunk line replacement in a difficult attic. Roy Castellanos will always price the repair in writing before we start, and if the repaired section fails within the year, our 365-Day Done Right Promise covers the rework at no charge.

Crushed and Kinked Flex Runs

Flex duct is the most common duct type in Miami residential construction, and it does not tolerate being stepped on, stacked on, or squeeze through a too-tight chase. A crushed flex run can reduce airflow to a room by half or more. We replace the damaged section rather than trying to round it back out, because a kinked liner never returns to full airflow.

Trunk Line and Plenum Damage

When the main trunk line is compromised, the symptoms show up across multiple rooms at once: weak airflow in every bedroom, a master bathroom that never cools, and supply temperatures that vary by 8 to 12 degrees from vent to vent. We see this most often in older homes in South Miami and Palmetto Bay where the original trunk was sized for a smaller AC system and has since been tapped repeatedly for additions, though Key Biscayne Duct Sealing calls show similar trunk-line wear in coastal properties. A proper repair includes resizing the tap and sealing the original trunk before reconnecting.

Air Duct Sealing

Air Duct Sealing is the specific treatment of the interior surfaces and access points of your ductwork to stop conditioned air from escaping into unconditioned space. The term is often used interchangeably with HVAC sealing, but in practice it refers to the sealant work done after the physical repairs are complete: mastic over every seam, foil tape on every joint, and a final pass with a negative-air machine in some cases to pull the sealant into hard-to-reach gaps. Hollis Air Duct Miami performs a full air duct sealing treatment on every can of the system, including the return chase, the filter box, and the area around the coil. A complete air sealing job costs between $600 and $1,300 depending on the duct configuration and whether we are sealing inside a conditioned closet or a scorching hot attic.

Interior Sealing with Negative-Air Assistance

For ducts that are buried under insulation or impossible to access from the outside, we use a negative-air setup that pulls the mastic into the leak paths from the inside. It is the same principle commercial kitchen crews use, applied at residential scale. The machine creates a controlled vacuum, and the sealant finds leaks the way smoke finds a crack in a door frame.

Mastic vs. Tape: What Actually Holds

Hardware-store foil tape dries out and fails inside a Miami attic within two to three seasons. Water-based mastic, applied correctly over a properly prepared surface, hardens into a durable seal that flexes with the duct. We see the difference on every service call where a previous company used tape alone. Our crews use mastic on every accessible seam and a reinforced UL-listed tape only where the joint needs mechanical support first.

Duct Sealing Services

Duct Sealing Services from Hollis Air Duct Miami include the full scope of work: inspection, pressure-based leak diagnostics, collar and seam sealing, plenum repair, insulation replacement where needed, and a final verification walkthrough. You are not selecting from a menu of confusing add-ons. The written estimate we give you covers the entire job at one price, and that price does not move when the technician arrives. We also provide duct sealing as a companion service to our home air duct cleaning and dryer vent services, which means you can handle both in one visit if that makes sense for your schedule. Typical residential sealing projects in Miami range from $450 for a smaller single-story home to $1,400 for a two-story or split-plan home with a long trunk line and multiple returns.

Scheduled Service, Not Sales Calls

We do not run rush promotion offers or pressure you to book before the technician leaves the driveway. The estimate is yours in writing, you have time to think about it, and the price holds. When you call to schedule, a live person answers the phone at any hour of the day or night, writes down your details, and puts the job on the calendar.

Combining Sealing with a Full System Cleaning

If the ducts have never been cleaned and are leaking, we recommend sealing after a thorough cleaning, not before. Sealing over settled dust and debris locks it in place and wastes the sealant. Our Rotary brush system from Rotobrush and negative-air machines from Nikro are the standard tools we use for the cleaning side, and the sealing work follows once the interior surfaces are clean and dry.

Brands We Service

We service and seal ductwork connected to every major HVAC brand in the Miami market, because the sealant work does not depend on who built the compressor. That said, certain brands appear more often in our service calls. Trane and Carrier systems are the most common in newer homes in Doral and Aventura, while Goodman and Rheem units dominate the older construction in West Little River and Tamiami. The duct sealing process is the same, but the connection details at the plenum and the coil vary by manufacturer, and our crews know those differences.

For filtration upgrades that often pair well with a sealing job, we carry and install products from Honeywell and Aprilaire. These are not hardware-store filters. They are whole-house media cabinets and electronic air cleaners designed to work with a tight, properly sealed duct system. Whether you have a Trane, Carrier, Goodman, Rheem, Lennox, or any other make, we can seal the ductwork and make sure the air reaches where it was designed to go.

Signs You Need a Pro Right Now

• Rooms at opposite ends of the house are 5+ degrees apart. If the thermostat says 74 but the west-facing bedroom reads 80 on a cheap thermometer, you have an airflow problem. That difference usually means a disconnected or crushed run, not a weak AC. We find it with a walkthrough and pressure testing, not guesswork.
• Your electric bill spikes in summer while the AC runs nonstop. Cooling a Miami house with leaky ducts is like running the AC with the front door open. The compressor never cycles off because the thermostat never reaches setpoint. Sealing the ducts shrinks that runtime and the bill.
• Dust accumulates on furniture within days of cleaning. A return-side leak pulls attic air, and attic air carries fiberglass particles, insulation dust, and whatever the roof has been shedding for a decade. If your nightstand looks dusty on a Tuesday after a Saturday clean, your ductwork is pulling air from the wrong place.
• You hear whistling or rattling behind certain registers. Air escaping through a small gap makes exactly that sound. It is not a normal duct noise, and it points to a specific joint that has opened. Ignoring it does not save money; the gap only grows.
• Some vents barely move a tissue while others push hard enough to flutter the curtains. This is a classic sign of a trunk line failure or a collapsed run. The air is still being produced, it just is not being distributed. A sealed system delivers balanced flow to every room.

Our Process, Step by Step

1. 1
   Walkthrough and written estimate. A background-checked, uniformed technician arrives within the quoted window, walks the attic and accessible ductwork with you, and writes the full job scope and price on the estimate sheet before any tool comes out. The price on that sheet is the price you pay, period.
2. 2
   System inspection and leak diagnosis. We identify the easy leaks visually: separated collars, failed tape, crushed runs. Then we check the subtle ones with a smoke pencil at each accessible joint and, where the duct layout allows, a duct pressure reading. This tells us whether the leaks are on the supply side, return side, or both.
3. 3
   Preparation and cleaning. Where the interior surfaces are covered in settled dust, we run a Rotobrush or Nikro negative-air setup to clear the surface so the sealant can bond. Sealing over dust is throwing money away, and we will not do it.
4. 4
   Sealing, repair, and insulation. We reseat collars, replace crushed sections, mastic every accessible seam, tape every joint with UL-listed material, and wrap or replace insulation where needed. This is the part where the skill matters, and our crews follow the same procedure on every job, in the same order.
5. 5
   Verification and site cleanup. We recheck the accessible joints with the smoke pencil, confirm the airflow at each register, show you the before-and-after photos, and leave the attic and workspace the way we found them or cleaner. Then we document the entire job and file your 365-Day Done Right Promise in writing.

How Much Does Duct Sealing Cost in Miami?

Our Service Area Near Miami

Hollis Air Duct Miami covers the full Miami metro from our local operation, including Duct Sealing in Miami Beach and neighboring communities like Doral, Aventura, Miami Lakes, Palmetto Bay, Sunny Isles Beach, South Miami, Fountainebleau, Tamiami, and West Little River. Most of our sealing jobs are scheduled within the same week the estimate is approved, and we arrive inside the quoted window on the day of service. If you are in Miami proper or anywhere in the surrounding metro, we are your local crew, not a call center routing work to whoever is available.

Frequently Asked Questions About Duct Sealing in Miami

Schedule Your Duct Sealing Service in Miami Today

Call (850) 660-3272 to schedule a free walkthrough and written estimate. A live person answers the phone 24 hours a day, 7 days a week. You get a firm price on paper, a background-checked crew in uniform, and a year-long written guarantee on the work. That is the Garrison Standard, and it is the only way we do business.

Written by Roy Castellanos, Owner at Hollis Air Duct Miami, serving Miami since 2004.