Signs your ducts leak
- Rooms that are hard to heat or cool.
- High bills compared with similar homes.
- Dusty rooms, or a stuffy attic in summer.
- Ducts in unconditioned spaces with visible gaps or crushed sections.
How ducts are tested
A duct leakage test pressurizes the duct system with a calibrated fan to measure air loss. Some states require it for new systems. It shows whether sealing is worth doing and lets you verify the result afterwards.
Sealing methods
- Mastic and foil tape on accessible joints, the standard approach.
- Aerosol sealing injected from inside the ducts, which reaches hidden leaks.
- Insulation on ducts in attics and crawlspaces after sealing.
Cost
Duct sealing commonly costs about $500–$2,500 depending on access and method. Ask for before-and-after leakage numbers.
