Air Duct Replacement in Los Angeles, CA

What actually gets replaced when ducts are replaced

Does the whole system have to go, or just the bad runs? Honest answer: it depends on what the old work is made of. A 1950s–60s galvanized trunk can be sound metal with failed joints. If grey or black tape at those joints looks like asbestos-containing material, nobody cuts it. That gets sampled, and abatement goes to a licensed abatement contractor before any demo.

Fiberglass ductboard plenums are different. They shed, hold odor, and once wet they stay that way. Those get rebuilt in sheet metal. Old flex is usually R-4.2 to R-8 and fails at predictable spots: kinked at turns, crushed flat on a joist, sagging between hangers, or pulled off the boot entirely.

Replacement means new boots sealed to the ceiling drywall, mastic at every collar, and strapping at the spacing the flex maker specifies. Uninsulated metal plenums near the coast sweat and rust at the seams, so those get wrapped.

Returns drive the rest. One hallway grille for a converted wall-furnace house whistles and pulls attic dust past the filter. Adding return area is often the bigger comfort change.

Tight crawlspaces, low attic clearance, register count, and asbestos all move the labor more than the duct itself does.