Duct Inspection and Repair in Brentwood

Most of the ductwork we open up in Brentwood was never part of the original house. Estate homes on the larger lots off Sunset and through the canyon streets were built long before central air was standard equipment, so ducts were added later and routed wherever there was room: over rafters in the attic, through tight crawlspaces, and along long trunk runs reaching additions and converted garages at the far end of a big lot. A single sharp bend over a rafter can cut a flex run's delivered airflow by a third, and a boot that separated from its register decades ago dumps conditioned air into the attic instead of the bedroom. The symptom homeowners describe is almost always the same: the living room is comfortable, the upstairs bedrooms never catch up on a warm afternoon, and the system runs far longer than it should to get there.

Local conditions make it worse. Attic temperatures above the insulation line climb past 130°F on a warm Westside afternoon, so the R-4.2 flex duct that was standard when many of these retrofits went in bleeds capacity across every foot of run before the air reaches the room. Canyon-adjacent attics in Sullivan and Mandeville also see steady rodent activity, and torn duct insulation and pulled-apart joints follow. On mornings when the marine layer holds, the system barely runs and nobody notices; the leaks only show up in the afternoon and on the bill. So we test rather than guess: static pressure at the air handler, temperature split across the coil, and a duct leakage test that puts a number on how much air the system is losing. That number also tells us whether a <a href='/services/ac-installation'>new system</a> would be limited by the duct rather than the equipment, and whether a <a href='/services/indoor-air-quality'>filtration upgrade</a> is realistic at the static pressure you already have.

California Title 24 ties duct work to equipment work. Replace a furnace, air handler, or condenser in an existing home, or alter more than 40 feet of accessible duct, and the duct system has to be sealed and leakage-tested by a third-party HERS rater. Altered systems are generally held to 15% or less of nominal system airflow, while a fully replaced duct system is held to the same tight target as new construction. Testing matters more here than in newer housing, because a retrofitted duct system in an older Brentwood home routinely tests at 25% to 35% leakage on the first pass. We seal with mastic and mesh at every joint, boot, and plenum connection, replace runs that are crushed or torn rather than taping over them, and bring insulation up to current R-value on anything running through an unconditioned attic.

Sealing and repairing an existing duct system in a typical Brentwood home runs $1,200 to $2,900 depending on how much of the attic is reachable and how many runs have failed. Full replacement, which is what long retrofit runs and collapsed flex usually need, runs $4,800 to $10,000 and scales with the number of supplies and the distance from the air handler to the far end of the house. Where an addition sits on its own long branch, redesigning that run is often cheaper than chasing leaks through it. Every job starts with a written estimate separating testing, sealing, replacement, and insulation, so you can decide how far to take the work. A room that has never held temperature usually needs a duct fix rather than a larger condenser, and pairing the work with <a href='/services/ac-maintenance'>annual maintenance</a> keeps the improvement measurable year over year.