Leaky, undersized, or poorly designed ducts waste 20–30% of the air your system produces. Fixing them is often the highest-return HVAC work you can do. Here's what it costs and how to approach it.
Duct service ranges from sealing leaks at joints and boots, to repairing crushed or disconnected sections, to resizing undersized trunks and runs, to replacing an entire system. A good contractor measures static pressure and airflow first to find where the losses are, rather than guessing.
Sealing is usually done with mastic or an aerosol sealant from inside the ducts. 'Duct cleaning' is a separate service — it removes dust but does not fix leaks or airflow problems.
Air isn't getting where it should — leaks, restrictions, or bad balance.
Conditioned air leaking into the attic or crawlspace is money straight out the vent.
Return-side leaks pull dust and attic air into the system.
Undersized ducts or a too-small return moving air too fast.
High static pressure from restricted ducts makes the blower work overtime.
Disconnected sections, crushed flex duct, or torn insulation in the attic or crawlspace.
Ranges for a typical single-family home.
| Service | Typical range |
|---|---|
| Seal accessible leaks (mastic) | $400 – $1,500 |
| Aerosol duct sealing (whole system) | $1,500 – $4,000 |
| Repair crushed / disconnected sections | $300 – $1,200 |
| Resize a trunk or add a return | $800 – $2,500 |
| Replace ductwork, single story | $3,000 – $7,000 |
| Replace ductwork, whole home | $6,000 – $14,000 |
| Add ductwork for a new heat pump / AC | $4,000 – $8,000 |
Duct work goes wrong when a contractor jumps to a fix without measuring. A thorough approach:
Be cautious of a contractor who recommends full duct replacement before measuring anything. Sealing and targeted repairs solve most problems at a fraction of the cost.
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Sealing accessible leaks with mastic runs about $400–$1,500. Whole-system aerosol duct sealing runs $1,500–$4,000. Both typically pay back through lower energy bills and better comfort.
Replacing ductwork for a single story runs about $3,000–$7,000; a whole home runs $6,000–$14,000. Adding ductwork for a new heat pump or AC runs $4,000–$8,000. The HVAC Cost Estimator factors ductwork into a full project.
No. Duct cleaning removes dust and debris; it does not fix leaks, airflow restrictions, or bad duct design. Sealing addresses the leaks that waste energy and pull in attic air.
Typical duct systems lose 20–30% of conditioned air to leaks, and more when ducts run through unconditioned attics or crawlspaces. Sealing is one of the highest-return HVAC improvements.
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