Duct Sealing in Houston, TX

Duct sealing in Houston attics

You feel attic heat at the registers. Rooms furthest from the air handler never cool. Dust returns to the shelves days after cleaning. These symptoms usually share one cause. Unsealed joints pulling attic air into the duct system. In a Houston attic that air is humid and loaded with blown-in cellulose or fiberglass.

Where the leaks sit depends on the duct type. Pre-1970 homes often have galvanized trunk-and-branch. Leaks show up at slip joints and the plenum takeoffs. Original fiberglass liner inside may be shedding by now. Sealing a duct that is shedding solves nothing. Fiberglass ductboard plenums from the sixties through eighties fail at the corner seams and staple lines. Flex duct, R-6 or R-8, is the dominant type since the eighties. On flex the real failure is the outer jacket, torn or slipped off the collar, letting humid air sit against the inner core.

Boots are the quiet offender. A ceiling boot sealed to drywall stops register sweating in July. Unsealed attic access panels and wall chases act as giant returns.

Mastic and mesh at collars, not tape. Cloth duct tape dries out and falls off here.

Sagging flex with crushed radii gets replaced, not sealed. Sealing a collapsed run is wasted money.