Ductwork repair and replacement in Santa Rosa, CA

Signs your ductwork needs repair

• Uneven rooms. The rooms farthest from the furnace or air handler lag several degrees behind.
• Weak airflow at some registers, even with a clean filter and the system running on high.
• Dust that returns within days, or bits of insulation and debris near supply registers.
• Musty or earthy smells when the system starts, a common sign that a return duct is pulling air from the crawlspace.
• High energy bills with equipment that tests fine.
• Whistling or rattling in the ducts, or a return grille that "sucks" hard.
• Visible damage: flex duct lying on the attic floor or crawlspace soil, torn outer jackets, tape hanging loose, or a run that has dropped off its fitting.

What causes leaky and damaged ducts

• Age. Flex duct from the 1970s through the 1990s gets brittle. The inner liner tears and the outer jacket crumbles. Cloth duct tape dries out and lets go.
• Poor original installation: long, sagging runs with sharp bends, too few supports, or ducts sized for heating only.
• Foot traffic and other trades. Cable installers, roofers, and solar crews step on or move ducts in attics.
• Rodents, which nest in duct insulation and chew through flex duct.
• Moisture in crawlspaces, which soaks insulation and rusts metal ducts and boots.

Duct leakage testing and inspection

1. Room-by-room airflow and temperature. This shows which runs are underperforming.
2. Static pressure. Readings across the system show whether the ducts are too restrictive overall or whether the return is undersized.
3. Duct leakage test. A calibrated fan pressurizes the duct system with the registers sealed, measuring the total leakage in cubic feet per minute. This is the same test California's HERS raters use.
4. Visual inspection of the attic and crawlspace runs, connections, supports, insulation, and the plenum at the equipment.

Duct sealing, repair, or replacement?

Duct sealing

If the ducts are in decent shape but leak at the joints, sealing every connection with mastic or approved tape, and sealing the boots to the ceiling or floor, can cut leakage dramatically. This is often the most cost-effective fix.

Targeted duct repair

Reconnecting runs that have dropped off, replacing crushed or torn sections, re-hanging sagging flex on proper supports, and fixing kinks. This works well when the problems are local.

Ductwork replacement

When most of the flex is brittle, insulation is wet or rodent-damaged, or the layout was wrong from the start, replacing the duct system is the lasting fix. New ducts are sized from the load calculation, insulated to current code, sealed, and tested. Replacement often pairs well with a new air conditioner or heat pump, since the permit and testing are already happening.

Crawlspace ducts and Santa Rosa's wet winters

A large share of Santa Rosa's older homes, from the pre-war houses around downtown to many postwar homes, sit on raised foundations with ductwork running through the crawlspace. Santa Rosa gets nearly all its rain between November and April, and heavy winter storms can leave crawlspaces damp or with standing water for days.

Ducts in that environment fail in specific ways. Runs that have fallen off their hangers end up lying on wet soil. Insulation soaks up water, loses its value, and smells.

Metal boots and older sheet-metal ducts rust through. Rats and mice move into the dry insulation, especially in winter. Any leak in a return duct then pulls that damp, musty crawlspace air straight into the system and through the house.

For homeowners: after a heavy storm, look into the crawlspace with a flashlight. Ducts should hang clear of the soil on straps or supports, with no water pooling beneath them. If you see sagging ducts, torn insulation, or droppings, have the ducts inspected.

A ground vapor barrier and proper drainage protect the duct repair. Musty smells from the vents in winter are a common sign, and our indoor air quality page covers the related filtration fixes.

What affects duct repair and replacement cost

• Scope: sealing joints, repairing a few runs, or replacing the whole system.
• Access: a tall, open attic is quicker than a low attic over vaulted ceilings or a crawlspace with 18 inches of clearance.
• House size and layout: the number of supply runs, returns, and floors.
• Damage cleanup: removing rodent-contaminated insulation or wet materials before new work goes in.
• Return changes: adding returns or enlarging them to fix airflow.
• Permit and HERS testing when ducts are replaced or the work is part of equipment replacement.

When a duct problem is urgent

Most duct work can be scheduled. One situation can't: a disconnected or leaking return duct in a garage or in a closet with a gas water heater or furnace. A return leak there can pull combustion gases into the duct system and through the house.

If you find a disconnected return near gas appliances, or your CO alarm sounds, shut the system off and call 911 if anyone feels ill. Then call us.

Duct repair is often the missing piece in HVAC repair in Santa Rosa. A new system can't overcome ductwork that loses a third of its air.

Ductwork repair FAQs