Up to 30% of the air your system produces never makes it to your rooms. It leaks out at joints, connections, and gaps — usually into your attic, where it does absolutely nothing for your comfort but everything to your bill.
Snapshot
Category
HVAC performance
Focus
Fix hidden HVAC losses
Next step
Consultation
Overview
The air you’re paying for is going into your attic.
You set the thermostat to 72, but the bedroom reads 78. The kitchen is fine, but the living room won’t cool down. Before you blame the AC unit, look at the delivery system. Every loose joint, torn flex duct, and disconnected boot is a hole where cooled air escapes into 140-degree heat. And those leaks also pull hot attic air and dust into your supply stream. Duct sealing with mastic and metallic tape closes those gaps — and a before/after pressure test proves it worked.
What a good duct sealing plan should cover
Pressurized testing shows exactly how much you’re losing
A duct blaster test measures total leakage as a hard number. Most homes test at 20–30% leakage. After sealing, that drops below 10%. You see the before and after side by side.
Joint and connection sealing targets the worst leaks
The biggest losses happen where duct sections meet boots, plenums, and branch lines. Mastic sealant and metallic tape at these connections stop the majority of air loss in one pass.
Better airflow means more even temperatures
That back bedroom that never cools down? It’s probably at the end of a duct run with leaks upstream stealing its air. Seal those leaks and airflow rebalances — no new equipment needed.
How duct sealing should be approached
1
Pressurize the duct system and measure total leakage in CFM
A duct blaster test seals the registers and pressurizes your duct system to measure exactly how much air escapes before it reaches your rooms. Most Texas homes test at 20–30% leakage. This baseline tells us exactly how bad the problem is and where to focus.
2
Seal every joint, boot, and connection with mastic — not duct tape
Mastic sealant and UL-rated metallic tape go on every accessible joint where duct sections meet boots, plenums, and branch lines. Crushed flex gets reshaped or replaced. Disconnected runs get reconnected. Standard duct tape dries out and fails in a 140°F Texas attic within two years — which is why we don’t use it.
3
Retest to confirm leakage dropped below 10% and check every register
The duct blaster runs again so you see the improvement as a hard number. Then we measure airflow at each supply register to confirm air reaches every room. That back bedroom that never cooled down should be getting its full CFM now.
Duct Sealing questions
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The goal is a clearer recommendation, a cleaner plan, and the right conversation first.