Duct Sealing in Venice, FL

Why sealing ducts matters more than cleaning them

The back bedroom never cools. The thermostat reads low. The air feels clammy, and the system runs almost all day. That pattern is rarely a weak compressor. It is usually leakage. Insulated flex duct in a vented attic sits in brutal summer heat. Every loose collar and torn inner liner bleeds conditioned air into that space, and a leaking return plenum pulls hot humid attic air straight back into the handler.

Sealing starts at the connections, not the middle of a run. Takeoffs, boots, plenum seams, and the air handler cabinet are where most of it happens. Brush-grade mastic with fabric mesh is the standard. Cloth duct tape fails on these jobs. Ductboard trunks from the 1970s through the 1990s get treated differently than sheet metal, because aged board sheds fiber and the facing often will not hold adhesive anymore.

Some findings are not sealing problems at all. Branches lying disconnected in blown insulation need reattachment. Crushed flex in a tight attic run needs rerouting. Sweating boots staining ceiling drywall usually mean missing insulation contact, not a hole.

Under-slab ducts in 1950s and 1960s ranches are the hard case. They flood and hold water. They stay musty. Sealing them is often throwing good money after bad.