How often should you inspect ductwork?
Updated July 2026
Walk and visually inspect your accessible ductwork every 2 to 3 years, and lean to every 2 years for runs in an unconditioned attic or crawlspace where things shift and critters visit. You are looking for disconnected joints, crushed flex duct, and gaping seams. It matters because the U.S. Department of Energy puts typical duct leakage at 20 to 30% of the conditioned air moving through the system, and a single blown-off boot in the attic dumps a big share of what you paid to heat or cool.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Ducts in an unconditioned attic or crawlspace | Every 2 years | Temperature swings and rodents loosen joints and tear flex |
| Ducts inside conditioned space | Every 3 years | Lower stakes and slower to come apart |
| One room never gets comfortable | Inspect now | A disconnected boot or crushed flex is starving that run |
| Energy bills jumped with no rate change | Inspect and seal | A joint likely let go and is leaking conditioned air |
| After attic work, pests, or a renovation | Inspect now | Techs and rodents dislodge flex duct constantly |
| Home 15+ years old, never inspected | Inspect, consider a duct test | Old tape and mastic dry out and release |
The cost of skipping it
What skipping it costs: leaky ducts are the quietest money drain in a house. With the DOE's 20–30% leakage figure, a chunk of every heating and cooling dollar heats your attic instead of your living room, and the comfort side shows up as hot and cold rooms the thermostat can never balance. A fully blown-off boot can dump conditioned air into an attic for years unnoticed. Sealing accessible joints with mastic is a low-cost fix, and duct sealing often pays for itself in a season or two of lower bills.
How to do it (30 minutes · DIY visual check)
- Turn the system fan on so you can feel for air escaping at the joints.
- In the attic or crawlspace, trace the trunk and branch runs with a flashlight, looking for separated joints, sagging or crushed flex, and gaps where a boot meets the ceiling.
- Run a hand along accessible seams with the fan running: air blowing on your skin is a leak.
- Check that flex duct is supported and not pinched, kinked, or torn, and that insulation still wraps it.
- Mark leaks and mastic-seal the ones you can reach; note larger disconnects for a pro.
- While you are up there, confirm no ducts have come loose from registers or the air handler.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing ductwork inspections schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
Is inspecting ductwork the same as cleaning it?
No, they solve different problems. Inspection looks for leaks, disconnects, and crushed sections that waste energy and unbalance rooms, and it is a cheap every-two-to-three-year habit. Air-duct cleaning removes dust and debris from inside the ducts and is an occasional, need-based job, not a routine one. Most homes get far more from a good inspection and seal than from repeated cleanings, because sealed, connected ducts are what actually cut bills and fix comfort.
How do I know if my ducts are leaking?
The everyday clues are rooms that never match the thermostat, rising energy bills with no rate change, excessive dust, and rooms that feel stuffy or drafty. In the attic you can often feel air escaping at a joint with the fan on. For a real number, an HVAC contractor can run a duct-leakage (blower-door or duct-blaster) test, worth doing on an older home before you spend on sealing so you know what you started with.
Can I seal duct leaks myself?
The accessible ones, yes. Brush-on duct mastic or UL-rated foil tape on joints you can reach in the basement, attic, or crawlspace is a straightforward DIY job, and despite the name you never use cloth duct tape, which dries out and falls off. What needs a pro is sealing ducts buried in walls or ceilings, reconnecting a fully separated trunk, or replacing crushed and torn flex duct that has outlived its service life.