Do leaky ducts really matter in winter?
Yes. The U.S. Department of Energy estimates a typical duct system loses 20–30% of its air to leaks and poor connections. In winter, that's heated air dumped into attics, crawlspaces and wall cavities.
Leaks on the return side can also pull cold, dusty or damp air from crawlspaces into the system.
Signs your ducts need repair
- Rooms with weak airflow or none at all
- A warm attic or crawlspace in winter
- Dust around registers and on furniture
- Kinked, crushed or sagging flexible duct
- Tape peeling off duct seams
- High bills with a furnace that tests fine
Duct problems and repairs
| Problem | Repair |
|---|---|
| Disconnected run | Reattach with clamps and mastic |
| Crushed or kinked flex | Replace the section and support it properly |
| Leaky seams and joints | Seal with mastic or UL-181 foil tape (not cloth duct tape) |
| Uninsulated ducts in attic or crawlspace | Add duct insulation after sealing |
| Damaged boot at the register | Reseal the boot to the drywall or subfloor |
Why 'duct tape' fails on ducts
Common cloth duct tape dries out and lets go within a few seasons, especially on ducts that heat and cool. Mastic sealant and UL-181 rated foil tape are the materials made for the job.
A good repair seals first, then insulates.
How duct repair is done
- Visual inspection of accessible ducts in attic, basement and crawlspace.
- Optional duct leakage test (duct blaster) to measure total leakage.
- Repair disconnects and crushed runs first; they're the biggest losses.
- Seal joints, boots and the plenum connection.
- Re-measure airflow at affected rooms.
Combustion safety check
Sealing return leaks near a gas furnace or water heater changes air pressure in the utility room. A careful provider checks that combustion appliances still draft properly after duct work.
Duct FAQs
Is duct cleaning the same as duct repair?
No. Cleaning removes debris; repair fixes leaks and disconnections. Leaks affect heating performance far more than dust does.
Can I seal ducts myself?
Accessible basement ducts are a reasonable DIY job with mastic. Attic and crawlspace work in winter is harder and riskier. Hire a pro if access is tight.
Next steps
Ready to get it fixed? Call (888) 555-0142 to reach a licensed provider in your area. Related guides:
Busy winter markets: heating repair in Wisconsin · heating repair in Colorado · heating repair in New Jersey · heating repair in Missouri · heating repair in Indiana · heating repair in Washington · all states.