Duct Sealing in San Jose, CA

Duct sealing in San Jose homes

One bedroom never cools. The bill climbs every summer. Dust returns two days after you wipe. Usually that is air escaping before it reaches the register, and attic air getting pulled in to replace it.

Leaks sit in predictable places. On 1950s–70s rigid galvanized trunks, it is the transverse seams and the branch takeoff collars. Plenum joints at the furnace leak too. On flex-duct homes, the inner liner slips back off the collar after years of thermal cycling in a vented attic. Boots drop away from the ceiling drywall and dump conditioned air into insulation.

Sealing means mastic, often with embedded mesh on wider gaps, over a mechanical fastening first. Cloth duct tape does not belong in an attic here; the adhesive bakes out and the tape peels. Foil tape works on clean metal only.

The return side matters more than most homeowners expect. Panned joist returns and one central hallway grille are common in tract stock. Leaks there pull attic fiber and spring pollen past the filter. Late-summer smoke residue gets through too.

Sealing is the wrong call on torn liner, crushed runs, or rodent-nested duct. Those get replaced. Attic clearance and boot count drive how long the work takes.