Replacing Flex Ductwork in Houston Attics: Signs, Code and What to Expect

Most Houston homes move every bit of cooled air through flexible ductwork in the attic. Flex duct is quick to install and easy to route, which is why builders use it. It is also the part of your system that takes the worst of the Houston climate: summer attic heat, Gulf humidity, and years of people stepping on it to reach a box of decorations. When it fails, your system works harder to deliver less air, and you pay for that every month.

Here is how to tell when your ductwork needs replacing, what a proper replacement includes, and what drives the cost. Beede AC & Heating has worked in Katy and Houston attics since 2010.

Why flex duct wears out faster in Houston attics

Heat. On a July afternoon a Houston attic can pass 130°F. Years of that bakes the outer jacket brittle until it cracks and tears.

Humidity. When the insulation is thin or torn, cold supply air meets humid attic air and the duct sweats. The water soaks the insulation, drips onto the drywall and takes out what is left of the insulation value.

Sagging. Flex has to be strapped and supported along its length. Without enough support it sags, and every sag chokes airflow.

Crushing. Storage boxes, cable installs and past repairs flatten runs. A run crushed to half its size moves far less than half its air.

Age. Older flex was built to lower insulation values than current code. Even without damage, it loses more cooling to the attic than new duct.

7 signs your Houston home needs new ductwork

• Rooms that never cool down. The room at the end of the longest run is usually the first to suffer. See why some rooms are hotter than others.
• Power bills that rise with no change in how you use the system.
• A torn or cracked outer jacket you can see from the attic hatch.
• Sweating ducts or water stains on ceilings under a duct run.
• Kinked, crushed or sagging runs lying across the attic.
• Weak airflow at 1 or more registers while others blow hard.
• Disconnected runs. A run that has pulled loose at a boot or the plenum cools your attic instead of your home. We find these more often than you would think.

Repair or replace?

A single crushed run or 1 disconnected boot is a repair: reattach it, seal it, strap it. When the problems are spread across the attic, when the outer jacket is brittle everywhere or the insulation is soaked, patching 1 run at a time costs more over 2 summers than replacing the system of ducts once. Your tech will tell you which one you have and show you photos from your attic.

What a full duct replacement includes

• Sizing every run for the airflow that room needs, not copying what was there before.
• R-8 insulated duct. Current energy code calls for R-8 insulation on ducts in an attic. Much of the older flex in homes built before current code is rated lower.
• Sealed connections with mastic at every joint, collar and boot.
• Proper support, strapped so runs stay straight, open and off sharp edges.
• New plenums, boots and collars where the old ones are rusted, crushed or leaking.
• Haul-off of the old duct.
• An airflow check at every register before we leave.

What duct replacement costs in Houston

4 things set the price: how many systems the home has, how many supply and return runs each system feeds, how easy the attic is to work in, and whether the plenums and boots need replacing too. A 1-story home with 1 system and an easy attic sits at the low end. A 2-story home with 2 systems and a tight attic takes more labor.

As a rough guide, full duct replacement in Houston runs about $450 to $600 per vent. Your exact price depends on the 4 things above, and you get it in writing at a free estimate.

Estimates for whole-home duct replacement are free. We price it flat and in writing before any work starts. Financing available through Hearth.

Replace ducts with your AC, or separately?

If your AC or furnace is near the end of its life, do the ducts at the same time. The attic is already open, the crew is already there, and the new system gets matched to ductwork that can carry its airflow. A new high-efficiency system on old, leaking, undersized duct never delivers the efficiency on the label. See AC installation and replacement.

If your system is newer and the ducts are the problem, replacing the ducts alone is the right call.

Duct replacement questions we get in Houston

Do you need a permit to replace ductwork in Houston?

Inside the City of Houston and in most surrounding cities, yes. Duct replacement is mechanical work and needs a permit. We pull it.

How long does it take?

It depends on how many systems the home has and how easy the attic is to work in. You get the schedule with your written price.

Will new ducts fix a hot room?

Often, when the cause is a crushed, leaking or undersized run. If the room is hot because of afternoon sun or missing attic insulation, we will tell you that too.

Can you replace only the bad runs?

Yes, if the rest of the system is in good shape. A torn run or a disconnected boot is a repair job: it starts with the $99 diagnostic, and you get the repair price before any work starts.

Book a duct inspection

A Beede tech will go into your attic, photograph what is there and give you a written price. Estimates for whole-home duct replacement are free. If you have 1 torn or disconnected run, book a $99 diagnostic and we will price the repair. Call 281-222-9591 or book online. We serve Katy, Cypress, Richmond, Sugar Land, Fulshear and the rest of West Houston. License # TACLB68911E.