What this covers
Ductwork carries conditioned air from the furnace or air handler to every room and brings it back. New ductwork is designed from the room loads: trunk and branch sizes, register locations and return paths that give each room the air it needs at a quiet velocity. The installer hangs sheet metal trunks and round branches, or insulated flex run straight and taut, seals every joint with mastic or foil tape, and insulates ducts in unconditioned spaces. Repair work finds the disconnected boots, crushed flex and open seams that leak a quarter or more of a system's air into attics and crawlspaces, and corrects them. The company tests airflow at the registers when the work is done.
When to call
- Rooms that are much warmer or colder than the thermostat setting.
- Dusty rooms, whistling registers, or a system that runs long without catching up.
- Ducts visibly disconnected, crushed or sagging in the attic, basement or crawlspace.
- A new furnace or air conditioner that the old ducts cannot supply with enough air.
- Ductwork soaked, soot-filled or torn out during a water or fire loss.
What to expect
- AssessThe existing ducts are inspected and airflow measured at the registers to find what is missing.
- DesignRoom loads set the trunk, branch and return sizes and the register locations.
- Install or repairNew runs are hung and connected, or disconnected, crushed and leaking sections replaced.
- Seal and testEvery seam is sealed, exposed ducts insulated, and airflow checked room by room.
Get a certified company
Look up a certified company by ZIP code. Every company's license, insurance and trades are verified before it is listed, and placement is never paid.
Questions people ask
Why does duct sealing matter?
Leaky supply ducts push heated or cooled air into the attic or crawlspace, and leaky returns pull in dusty, humid air from those spaces. Sealing restores the airflow the equipment was sized for.
Metal or flex duct?
Sheet metal lasts and flows well in trunks and long runs; insulated flex is practical for short branches when pulled straight and supported. Kinked, sagging flex is the most common defect the company finds.
Will walls or ceilings be opened?
Sometimes, when a new run must pass through finished space. The company plans routes through chases, closets and soffits first, and any drywall opened is patched and ready for paint.
Related: Air duct cleaning · Furnace installation · Drywall repair · All heating, cooling and air quality
This page describes what the service involves. The company you hire sets the scope, the schedule and the price, and your contract is with that company. We verify credentials and collect reviews from real jobs. We do not guarantee any company's workmanship. Safety steps are general guidance. When in doubt, leave the home and call 911.