Ductwork is easy to overlook because you never see it working — or failing. But leaky ducts are one of the most common, and most fixable, reasons a home’s energy bill runs higher than it should.
Sealing duct leaks is one of the higher-value repairs available — most homeowners see it pay for itself in a season or two. A duct repair visit starts with finding where you’re actually losing air.
How Much Air Actually Gets Lost
Studies on typical residential duct systems have found that a significant share of conditioned air — often 20–30% in systems with notable leaks — never reaches the rooms it was meant for, escaping through gaps at joints and seams into attics, crawlspaces, and wall cavities instead.
Where It Shows Up on Your Bill
- Your system runs longer to reach the same temperature, because a portion of every cycle’s output is being lost along the way.
- You may run the thermostat lower or higher than needed, unconsciously compensating for rooms that never quite get comfortable.
- Your equipment ages faster, since it’s working more cycles and more hours than it should need to.
It’s Not Just About the Bill
Ducts running through unconditioned spaces (attics, crawlspaces) that leak can also pull in dust, insulation particles, and outside air — including humid air in summer — which affects both air quality and how hard your system has to work to dehumidify.
How to Tell If This Is Happening to You
- Rooms that are consistently harder to heat or cool than others (see our room-by-room guide).
- Visible gaps, disconnected sections, or crushed ductwork where it’s accessible (attic, basement).
- Higher-than-expected bills despite a system that’s otherwise in good condition.
- Dust accumulating faster than it used to.
The Fix
Sealing duct leaks — at joints, seams, and connections to registers — is one of the higher-value repairs available, often paying for itself through lower bills within a few seasons, on top of making the whole house more evenly comfortable.