Signs the ductwork is the problem
If rooms far from the unit stay warm while the rest of the house is fine, the ducts may be part of the problem. Dust can build up fast, or the house can feel stuffy and humid. In the attic, we look for flex duct that’s crushed, kinked, sagging, disconnected at a joint, or sweating, along with old duct board with torn facing. A new AC on bad ducts still leaves those rooms warm, so we look at the ducts on every replacement visit.
What ductwork replacement covers
Ductwork replacement covers the supply plenum, the sheet-metal box on the equipment that feeds the ducts. It also covers the trunk lines, branch runs to each room, boots at the ceiling, and return. We use insulated flex or sheet metal for new runs, hang them with wide straps, and keep them short and straight. We seal every joint with mastic, a thick sealing paste, and size the runs for the airflow each room needs, following Manual D, the duct design method from ACCA (the Air Conditioning Contractors of America).
Duct testing under Austin's energy code
Austin’s energy code calls for a duct leakage test when a job relocates a quarter or more of the registers or the ductwork, or adds a quarter or more to the duct length. Our permits section gives the exact thresholds and the leakage limit.
Replacing ducts with a new system
The cheapest time to replace ducts is with a new system because the equipment is already out and the plenum, the box connecting it to the ducts, is open. We size the new ducts to the new system’s airflow. HomeGuide (2025) puts a full system with new ductwork at 3 to 5 days, compared with 1 to 2 days on existing ducts.
Ductwork replacement cost in Austin
Angi’s Austin HVAC page (updated April 2026) publishes a range of $6,000 to $12,000 for ductwork installation in a typical 2,000-square-foot home in Austin. Our cost guide also lists HomeGuide’s published national duct range of $1,400 to $5,600 (December 2025).
Austin Energy duct rebates
Austin Energy’s Home Energy Savings program pays $3.25 per linear foot for duct replacement and $0.20 per square foot of floor area for duct sealing through a participating contractor, as part of at least three upgrades. Our rebates guide lists the program’s other rebates and its rules.
Ductwork questions
Can you replace ducts without replacing the AC?
Yes, we can replace your ducts while keeping your AC if the equipment is fairly new and working well. If the system is near the end of its life, doing both together saves opening the attic twice.
How do I know if my ducts leak?
Rooms that never cool, dusty registers, and disconnected or torn ducts in the attic can be signs of leaks. A duct leakage test pressurizes the duct system and measures how much air escapes.
How long does ductwork replacement take?
It depends on the size of your house and how many duct runs change. HomeGuide (2025) puts the job at 3 to 5 days when the ductwork is new and you’re getting a new system.