Leaking duct joints dump conditioned air into the attic and pull attic air back in. We seal every connection with UL 181 mastic — or replace runs that are crushed, torn or rotted.
Duct leakage is the quiet one. You don't see it, you don't smell it, you just pay for it — every month, in an AC that runs longer than it should and rooms that never quite get there. In South Florida attics, the ducts are sitting in 130°F air; every leak is a direct line between that air and your living room.
Tape fails in heat. Mastic doesn't. We brush water-based, UL 181-listed mastic over every boot, collar, plenum and distribution-box connection. Where flex duct is crushed, torn, chewed or has a rotted inner liner, we replace the run with new R-8 flex properly supported and strapped.
Boots, collars, main-line joints, distribution boxes, plenum — each one counted and photographed. Your quote shows the number.
Water-based UL 181 mastic brushed over every joint, with mesh where gaps need bridging. No tape.
Crushed, torn or rotted runs replaced with new R-8 flex duct. Distribution boxes and plenums replaced where needed.
Runs strapped and supported at code intervals, sharp bends and kinks removed, no runs lying in insulation.
Register airflow checked room by room against the before readings.
Photos of sealed and replaced connections in your packet.
Every product is named on your quote and your contract. We don't substitute without your written approval. See everything we install.
Sealing is priced per connection; replacement is priced per run and per box or plenum. Both are itemized on your quote. A typical home has 30–50 connections, and sealing all of them is usually the best return on the whole job after air sealing the ceiling.
Mastic. Cloth duct tape fails within a couple of years in attic heat. Even UL 181 foil tape is a second choice. Brushed mastic bonds permanently and flexes with the duct.
If the duct itself is intact, yes — sealing the connections fixes most leakage. If the inner liner is rotted or the run is crushed, sealing the joints doesn't help and we'll show you why.
We replace individual runs, distribution boxes and plenums. A complete system redesign is an HVAC contractor's job; if that's what you need, we'll say so.
Room-by-room airflow readings before and after, plus photos of every sealed connection. Most customers feel the difference at the far registers the same day.
Usually yes, when they need it — cleaning before sealing means we're not sealing debris in. Both are on the same visit when we do them together.
CertainTeed fiberglass to R-30 or R-38 with depth markers.
Learn more →Every gap at the ceiling plane sealed — fire-rated where it matters.
Learn more →Rotary-brush cleaning to NADCA ACR standard, then sanitized.
Learn more →Free inspection. Written report the same day. Three honest prices. Open 7 days.
