Duct Sealing in Houston, TX

Why sealing ducts stops the back bedroom from cooling poorly

The symptom is usually one room. It stays warm while the hallway freezes. Or the registers whistle. Or gray dust films the grille within days. All three point the same direction: air is leaving or entering the system somewhere it shouldn't. In Houston attics that somewhere is rarely the straight runs. It's boots, collars, plenum seams and returns.

The common one here is a flex duct inner liner that slipped off its collar. The outer jacket still looks connected. Conditioned air dumps into attic insulation behind it. Another is the boot at a ceiling register, pulled loose from the drywall. You can check that one yourself. Pop the grille and look for daylight gaps around the metal.

Return-side leaks matter more than supply leaks. A leaky return plenum at the air handler pulls attic dust and loose fiberglass straight across the coil. That's why the filter loads fast.

Sealing is mastic on seams, not tape alone. Attic heat cooks tape adhesive off sheet metal eventually.

Some ducts shouldn't be sealed. Crushed flex, shedding duct board liner, or crawlspace runs soaked in a flood need replacing. Sealing those just locks the problem in.