Homeowners replace air conditioners and keep thirty-year-old ductwork attached to them. It is one of the most common mistakes we see in Houston, because the ducts are out of sight in a 130-degree attic and nobody thinks about them until the new expensive system somehow still cannot cool the back bedrooms.
The warning signs
Ductwork rarely fails all at once. It degrades, and these are the symptoms:
- Uneven rooms. The thermostat says 74 but the rooms farthest from the air handler never get there. Crushed, kinked or undersized ducts starve those rooms of airflow.
- Rising bills with a healthy AC. If the equipment checks out but consumption keeps climbing, the air you paid to cool may be leaking into the attic. In older Houston homes, losing 20 to 30 percent through duct leaks is not unusual.
- Dust that always comes back. Leaky return ducts pull unfiltered attic air into the system and distribute it through the house.
- Humidity and musty smells. Leaks and missing insulation let Houston’s humid air condense on and inside the ducts. That moisture is how mold gets started.
- Age. Flex duct from the 90s or earlier has usually outlived its useful life: brittle outer jacket, compressed insulation, sagging runs.
Repair or replace?
Sealing and repairing makes sense when the duct material is sound and the problem is localized: a disconnected boot, a crushed section, leaks at the plenum. Replacement is the honest recommendation when the flex duct itself is brittle, when the insulation has flattened, or when the original layout was wrong from day one. Sealing a badly designed system just gives you a tighter version of a bad design.
What a replacement involves
A proper duct replacement in a typical Houston single-story home is one to two days of work:
- Load calculation and design. Room-by-room airflow requirements, not a copy of whatever was there before. This is the step that fixes the hot back bedroom.
- Removal of the old runs and cleanup of the attic space.
- New insulated duct, properly sized trunk and branches, sealed at every connection with mastic, not just tape.
- Balancing. Measuring airflow at every register and adjusting until the design numbers are met.
What it costs
For a typical Houston area home, a full duct replacement generally lands in the range of a few thousand dollars to the low five figures, depending on home size, attic access, number of runs, and whether the plenums and returns are rebuilt too. Be careful comparing quotes that look far apart: the cheap one is often reusing old plenums, skipping the load calculation, or sealing with tape that will not survive five Houston summers in a hot attic.
Questions worth asking on any quote, ours included: Is the design based on a load calculation? Are connections sealed with mastic? Is balancing included and verified? What is the warranty on labor, not just materials?
The payoff
Done right, new ductwork shows up in three places: rooms that finally match the thermostat, a quieter system because air is not being forced through kinks, and a lower bill because the cooling you pay for arrives where you live instead of escaping into the attic. It also lets your AC run shorter cycles, which extends the life of the equipment itself.
If some rooms in your home never cool right, or your ducts have not been looked at since the house was built, request an inspection here. We serve Houston, Katy, Sugar Land and Fort Bend, and we will tell you plainly whether yours need sealing, partial repair or replacement.
