Air Duct Replacement in San Rafael, CA

When is replacing ductwork the right call instead of cleaning it?

Cleaning fixes dirt. It does not fix torn flex. If the inner liner is shredded at the takeoff, or a boot has fallen off its register in the crawlspace, a brush and vacuum just moves the problem around. Rodent nesting inside old trunk lines is the other hard stop. Urine soaks into fiber insulation and stays. Ross Valley and hillside crawlspaces are vented and open to wildlife, so we see this often.

Pre-1940 Marin homes complicate things. Many were gravity systems converted to forced air. Joints were often wrapped in cloth or asbestos-containing material. We do not cut into suspect wrap. That gets tested first, and abatement is a separate licensed trade before any new duct goes in.

Replacement is also a chance to fix airflow mistakes. Older conversions usually have one undersized central return. New flex alone will not fix a starved blower. Return path and filter sizing get corrected at the same time, or you end up with the same dust and the same pollen pulled through leaky returns each spring.

What actually drives the work: run length, crawl or attic access height, plenum condition, and whether the air handler sits in a tight closet or garage.