The Scale of the Problem
The average home loses 20–30% of its conditioned air through leaks in the duct system before that air ever reaches the living space. In Austin, where attic temperatures can reach 140–160°F in summer, duct leakage is particularly costly. Every cubic foot of cool air that leaks into your attic is replaced by hot attic air infiltrating into your living space, a double loss that forces your system to work significantly harder.
Signs You Have Significant Duct Leakage
Rooms that are consistently harder to cool than others, particularly rooms at the end of long duct runs, often indicate leakage in the ducts serving those areas. High energy bills relative to your neighbors in similar-sized homes is another indicator. Excessive dust throughout the house can indicate duct leakage in unconditioned spaces. A system that runs constantly but struggles to maintain temperature is often working against significant duct losses.
How Duct Leakage Is Measured
The standard test for duct leakage is a duct blaster test, which pressurizes the duct system and measures how much air escapes. A well-sealed system should leak less than 5–10% of total airflow. Many Austin homes, particularly those built before 2000, test at 20–35% leakage.
What does this actually cost in Austin?
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Austin Energy offers free home energy audits that include duct leakage testing.
What Duct Sealing Costs and Saves
Professional duct sealing in Austin typically costs $400–$1,200 depending on the size of your home. The most common approach is aeroseal duct sealing, which involves pressurizing the duct system and injecting a polymer sealant.
Reducing duct leakage from 25% to 5% in a typical Austin home can reduce annual cooling costs by $200–$500. Austin Energy offers rebates of $200–$400 for verified duct sealing.
Duct Sealing vs. Duct Replacement
In some cases, particularly in older homes with deteriorated flex duct, duct replacement is needed. Duct replacement is more expensive, typically $1,500–$4,000 for a full system, but may be necessary if the duct material itself has failed. If you're replacing your HVAC system, it's worth having the contractor assess your duct system at the same time.
