Duct sealing is hands on remediation. We get into the attic or crawl space, work along the accessible runs, and close the places where air is escaping: the plenum takeoffs, the collar connections, the seams in rigid trunk, the flex duct straps, and the boots where the duct meets the ceiling register. Mastic and mesh do the sealing, not tape, because tape in a hot attic eventually lets go.

The reason this pays off has to do with where the ductwork lives. Florida houses are slab on grade with the air handler and duct system in the attic, and that attic is hot and humid for most of the year. Every open seam on the supply side sends cold air into that space. Every gap on the return side sucks hot attic air into the system. Closing those two paths is often the single most effective thing you can do to a duct system.

Sealing also solves problems people do not associate with ductwork at all. Rooms that never keep up frequently improve, because the air that was leaking upstream now reaches the register. Dust drops, because the return stops pulling attic debris through the filter. And the house dehumidifies better, since the equipment stops fighting outdoor moisture it was never meant to handle.

Boot connections are the classic offender. The flex duct is strapped over the boot collar and sealed, but the strap loosens or the sealant cracks, and now conditioned air is pouring into the attic a few inches from the ceiling it was supposed to serve. Because it happens above the drywall, homeowners feel the weak register and blame the equipment.

Plenum and takeoff joints are the expensive ones. These sit closest to the air handler, so the air moving past them is at the highest pressure in the entire system. A gap there loses far more air than a gap at the end of a branch. When we prioritize a sealing job, we start where the pressure is highest and work outward.

Our climate then compounds the damage. With summer dew points in the high sixties and low seventies, cold air leaking out around a duct joint chills the surrounding surface below dew point and water condenses. Wet insulation loses its value, wet framing and dust give mold something to grow on, and eventually a ceiling stain appears. So a leak that started as an efficiency problem in Freeport ends up as a moisture problem, which is a considerably more expensive one.