Air Duct Replacement in La Mesa, CA

When does duct replacement beat another round of repairs?

Ask that when the same run fails twice. La Mesa duct inventory is mixed. Original 1950s-60s galvanized trunk-and-branch still sits in attics and under raised floors. Gray and silver flex from the 1970s through the 1990s is the usual replacement candidate. Those inner liners crack and shed. Tape mastic dries out. Once a liner sheds, sealing the outside fixes nothing.

Replacement means new take-offs, new boots, new plenum connections. Disconnected boots are a common finding here. A loose boot dumps cooled air into the attic and pulls attic dust and insulation fiber into supply air. Collapsed or kinked flex draped over joists starves the farthest bedrooms. We measure and re-route rather than re-hang the same sag.

Some pre-1960 metal plenums carry asbestos-era paper and tar wrap. That gets handled, not disturbed. Work stops and the scope changes. Crawlspace runs in older low-lying blocks also collect moisture. East-side attic and crawlspace runs sometimes hold rodent nesting and droppings. Contaminated duct gets removed, not cleaned.

Not every system needs full replacement. Sound galvanized trunk with bad branches is a partial job. We will say so. Duct layout, attic clearance, and register count drive the real scope.