What duct sealing means
Duct sealing is closing the leaks at duct joints, seams and connections with mastic or approved tape so the air you paid to heat or cool reaches the rooms.
Also called duct leakage, mastic.
Where it matters on a HVAC job
It is an easy sell once you show the leakage, and some energy codes require a duct leakage test. Price it by system, and test before and after if you can, so the customer sees what changed.
The numbers, with sources
- ENERGY STAR says that in a typical house about 20 to 30 percent of the air moving through the duct system is lost to leaks, holes and poor connections. (ENERGY STAR)
What it costs
For duct sealing, the closest koira.ai price is the ductwork replacement cost guide, near $1,250 for a typical job and $450 to $2,200 for most. The guide shows its sources and what moves the price.
Work it out
- Cost guide: Ductwork replacement cost
- Licensing: HVAC license rules by state
- Tools, templates and guides: Free HVAC resources
Sources: ENERGY STAR, Duct sealing. Checked October 9, 2026.