Ductwork & Air Quality
Duct replacement in Miami when patching no longer works
When most of the duct is torn, crushed, uninsulated or simply the wrong size, patching it one joint at a time costs more than starting over. We redesign the system around the rooms and replace it in a day or two.
Miami service office on SW 117th Ave · We answer 24/7
- Answered 24/7
- Miami service office
- Sized room by room
Updated October 2026
Duct replacement in Miami typically runs $3,000 to $7,500 for about 300 linear feet of new duct in published 2026 guides, depending on the house, access and how much redesign is needed. A technician from our SW 117th Ave office measures airflow, sizes each run from a room-by-room load calculation, and replaces the system with sealed, insulated duct.
The job
When replacing the duct makes more sense than repairing it
Duct repair is the right call for a few bad joints or a crushed run. Replacement makes sense when the jacket is torn along most runs, the flex has sagged into loops, the plenum is rusting, or the system was undersized from the start and rooms have never been comfortable.
A replacement is also a chance to fix the design: returns in the rooms that need them, runs sized to each room's load, and a layout that keeps duct out of the hottest part of the attic where possible.
What moves the price
What decides the price of new ductwork
Planning range: New ductwork, about 300 linear feet: $3,000-$7,500 in published 2026 guides. A market range, not our quote.
House size
More rooms mean more runs.
Redesign needed
New trunk sizing and routing take longer.
Returns added
Bedroom returns or transfer grilles.
Attic access
Shallow attics take longer to work in.
Materials
Sheet metal trunks or insulated flex.
Grilles and boots
New boots sealed to the ceiling.
Old duct removal
Hauling out the old system.
What we see on this job
Full duct redesign
A redesign starts with a room-by-room load calculation and a measurement of what the existing system actually delivers. From there we size the trunk and each branch so every room gets the air it needs at a reasonable velocity, plan the routing through the attic to keep runs short and supported, and choose where supply grilles sit in each room. The new system is sealed with mastic at every joint and insulated for attic conditions, and we measure static pressure and airflow when it's done.
Adding returns
Many Miami homes have a single central return in the hallway. When bedroom doors close, those rooms pressurize, airflow drops and they run warm and stuffy while the hallway is fine. Adding returns to bedrooms, or transfer grilles and jumper ducts that let air find its way back, balances the pressure. A duct replacement is the easiest time to add them, because the attic is already open and the return plenum is being rebuilt anyway, and it often fixes the rooms nobody could keep comfortable.
Duct board to flex conversions
Some older installs use fiberglass duct board for the trunk and plenum. When it's water-damaged, crushed or growing mold from years of condensation, it can't be cleaned or patched well. We replace failing duct board with sheet metal trunks or new insulated flex branches, depending on the layout, sealing and insulating every connection. Where the duct board is sound, we'll say so and only replace the failed sections, since not every board system needs to go, and a partial job costs noticeably less.
Local conditions
Why attic duct takes a beating in Miami
Miami International Airport hit 100 degrees on August 18, 2026, and on afternoons like that an unventilated Miami attic runs far hotter than the air outside. Duct lying in that heat for years loses its insulation, its tape and its shape, which is why so many replacement calls here come from homes where the duct is older than the air conditioner it serves.
Step by step
How a duct replacement runs
- 1
Measure the existing system
Airflow, static pressure and room temperatures.
- 2
Load calculation
Room by room, with a copy for you.
- 3
Design the layout
Trunk, branches and returns sized.
- 4
Remove the old duct
Hauled away, attic cleared.
- 5
Install the new system
Supported, sealed and insulated.
- 6
Boots and grilles
Sealed to the ceiling.
- 7
Measure again
Airflow and static pressure confirmed.
Timing
How long a duct replacement takes
Most Miami homes take one to two days, depending on the number of runs, attic access and whether returns are being added. We work in the attic in the mornings and keep the system running at night wherever possible, so you aren't left without cooling overnight.
Warning signs
Signs your ductwork needs replacing, not patching
Torn jackets on most runs
Insulation failing throughout the attic.
Flex sagging into loops
Airflow lost at every low point.
Rooms that have never cooled
Runs undersized from the start.
Rust on the plenum
Years of condensation at the air handler.
Moldy or crushed duct board
Board that can't be cleaned or patched.
Repeated duct repairs
Fixing one run at a time costs more.
Bedrooms stuffy with doors closed
No return path from those rooms.
FAQ
Questions Miami customers ask about duct replacement
Published 2026 guides put about 300 linear feet of new duct at $3,000 to $7,500.
Repair a few bad joints or runs; replace when most runs are torn, crushed or undersized.
Most homes take one to two days, with attic work done in the mornings.
It usually cuts runtime, because cooled air reaches the rooms instead of the attic.
Yes. It's easiest during a duct replacement, while the attic is open.
Not necessarily. We check the AC is sized correctly for the new duct design.
Same category
Related ductwork work we handle in Miami
UV Light Installation
Coil-mounted UV lamps, bulb replacement.
Air Filtration Systems
Media filter cabinets, filter upgrades for allergies.
Indoor Air Quality Testing
Humidity and temperature logging, moisture checks at the system.
Rooms never comfortable? The duct may be the problem
Call the Miami office to book an airflow measurement and a duct design for your house.
