Leaky ductwork is one of the biggest sources of energy waste in homes. Sealing ducts often provides better return on investment than equipment upgrades.
The Hidden Problem
Ductwork carries conditioned air throughout your home. But typical duct systems leak 20-30% of that air, according to Energy Star. In California, where ducts often run through unconditioned attics or crawlspaces, this loss directly affects comfort and costs.
Where Ducts Leak
Connections and joints where duct sections meet often separate or have poor seals.
Boots and registers where ducts connect to vents may have gaps.
Return air pathway leaks can draw in unconditioned air.
Damaged sections from age, pests, or accidental damage release conditioned air.
Signs of Duct Problems
- Uneven temperatures between rooms
- Dusty home despite regular cleaning
- High energy bills without explanation
- Weak airflow from some vents
- Visible duct damage or disconnection
- HVAC system running constantly
Benefits of Sealing
Energy savings of 20% or more on heating and cooling costs are common. When ducts stop losing air, your equipment works less.
Improved comfort as more conditioned air reaches living spaces. Problem rooms often improve dramatically.
Better air quality since sealed ducts do not draw in dust, insulation particles, or pollutants from unconditioned spaces.
Reduced equipment wear since the system runs less to achieve the same comfort.
More effective equipment because new, efficient equipment still wastes energy through leaky ducts.
DIY vs Professional
DIY sealing can address visible, accessible leaks. Use mastic sealant (not duct tape despite the name) on metal ducts. Seal obvious gaps and joints you can reach.
Professional sealing addresses hidden leaks with methods like Aeroseal, which seals from inside the duct system, reaching leaks you cannot access.
Professional duct testing measures actual leakage rates before and after, verifying improvement.
Combining with Other Improvements
Duct sealing makes other improvements more effective: - New equipment performs to its rated efficiency - Insulation improvements are not undermined by duct losses - Thermostat setbacks work better when conditioned air reaches rooms
Consider duct sealing before or alongside equipment replacement.
California Title 24 Requirements
When replacing HVAC equipment in California, duct sealing is often required. New systems must meet leakage standards verified by testing.
This requirement recognizes that equipment efficiency means little if the distribution system wastes the output.
Return on Investment
Duct sealing often pays back within 2-5 years through energy savings. Combined with improved comfort, it is frequently the best first investment in home performance.
If your home has older ductwork, especially in unconditioned spaces, consider sealing before investing in new equipment.