Duct Sealing
Your AC makes cold air. Your ducts deliver it. But if those ducts are leaking in a 140°F attic, you’re cooling the attic instead of your living room — and paying full price for air you never feel. Duct sealing closes those gaps so every room gets what it’s supposed to.
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.
- Category — HVAC performance
- Focus — Fix hidden HVAC losses
- Next step — Consultation
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
- 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.
- 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.
- 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
- Can duct sealing really lower energy use?
- Yes. If conditioned air is lost before it reaches your rooms, the system runs longer to compensate. Sealing cuts that waste and often makes the house noticeably more comfortable the same day.
- Is this worth doing if I’m replacing my AC soon?
- Absolutely — sealed ducts let you buy a smaller, less expensive system because it doesn’t have to overcome duct losses. It’s one of the best things to do before a new HVAC install.
Rooms that never cool down?
That's usually leaky ducts in the attic, not a bad AC. We test the ducts, show you the leakage number, and seal what's losing air.
Contact Texas Solar & Roofing Pros
Free estimates, no pressure, and no commitment. Numbers on this site are Central Texas ranges; your roof, usage, utility, and insurance carrier change them.
- Phone — (512) 775-0561
- Email — info@texassolarandroofingpros.com
- Address — 1700 Pagedale Cove, Cedar Park, TX 78613
- Service area — Austin, Texas, Round Rock, Texas, Georgetown, Texas, Cedar Park, Texas, Pflugerville, Texas, Kyle, Texas, Bastrop, Texas, Dallas, Texas, San Antonio, Texas, Waco, Texas, San Marcos, Texas
Machine-readable resources
Any public page on this site returns Markdown when the request prefers text/markdown (Accept: text/markdown). HTML clients that are not browsers receive this lightweight document; browsers receive the designed page.