The sealing test
A duct leakage test, step by step
It measures how much of the air your system makes actually reaches the rooms. You get both readings in writing.
- 01
Step 1: Close off the registers
We cover every supply and return opening, so the only way out for air is a leak.
- 02
Step 2: Pressurize the ducts
A calibrated fan pushes air in until the system reaches 25 pascals, a standard test pressure.
- 03
Step 3: Read the leakage
The fan’s gauge shows how much air escapes, in cubic feet per minute. That number goes in your report.
- 04
Step 4: Find the leaks
With the system pressurized we trace the leaks with a smoke pencil: seams, boots, the plenum, the air handler.
- 05
Step 5: Seal
Mastic over seams and around boots, foil tape rated for ducts where it suits. Insulation goes on after, never over a leak.
- 06
Step 6: Test again
We read the number a second time and put both in the report, so you see what changed.
What we seal with
Mastic and rated tape, not cloth tape
A hot attic is hard on a seal. These are the choices that last, and the ones that don’t.
| What fails | What we do | |
|---|---|---|
| Joints | What failsCloth “duct tape,” which dries out and lets go | What we doMastic brushed over the seam, or foil tape rated for ducts |
| Boots | What failsLeft open, so air leaks into the ceiling | What we doMastic around the boot and the gap in the ceiling |
| Plenum and air handler | What failsGaps that pull attic air into the system | What we doEvery seam and access panel sealed |
| Insulation | What failsWrapped over the leaks, where no one can see them | What we doAdded after sealing, with every joint covered |
Your report
What the report shows
Two readings, so the change is a number you can compare, and a plain list of what we found. We don’t grade your ducts or promise a result. The report shows what the ducts measured, where the air was escaping and what we did about it.
The leakage before we sealed, and after
Where the leaks were, with photos
What we sealed and with what
Insulation type and R-value, if we added any
Sealing questions
How do I know if my ducts leak?
A duct leakage test measures it. We seal the registers, pressurize the ducts with a calibrated fan and read how much air escapes. Signs you can see yourself: rooms that stay warm, dust streaks at joints, or an attic that feels cooler near the ducts.
Will sealing lower my electric bill?
It can, because leaks let cooled air escape into the attic. We can’t promise a number: it depends on how bad the leaks are, the attic and the system. We read the leakage before and after, so you see what changed.
Do you seal with duct tape?
No. Cloth duct tape dries out and lets go in a hot attic. We seal joints with mastic or with foil tape rated for ducts.
Why won’t one room cool?
Usually one of four things: leaks, a duct that’s crushed or kinked, too little return air, or a system that was never sized for the room. The test and a look at the attic tell us which.
Ready to find out what yours measure?
Book a duct check. The test and the report come with it.