Most homes in San Leandro, San Lorenzo and Castro Valley have their ductwork in the attic or the crawlspace, out of sight for decades. Duct cleaning removes the dust, debris and contamination that collect inside the supply and return runs and around the blower. It helps most when there is a clear reason for it: a remodel, debris blowing out of the registers, signs of rodents or insects, or a musty smell when the system starts.
When cleaning helps, and when it won’t
| What you notice | Likely source | Will cleaning help? |
|---|---|---|
| Dust puffs from registers when the blower starts | Debris inside the ducts or blower compartment | Yes |
| Fine white dust after drywall work or sanding | Construction dust pulled in through the returns | Yes, once the work is finished |
| Droppings, nesting material or a rodent smell | Pests in crawlspace or attic ducts | Yes, along with repairing the damaged run |
| Musty smell when the system starts | Moisture at the coil, drain pan or in damp ducts | Only after the moisture problem is fixed |
| Furniture dusty again a few days after dusting | Ordinary house dust from people, fabrics and outdoors | Usually not; filtration and sealing do more |
| Pet dander and allergy flare-ups | Particles circulating through the house | Partly; the filter does the daily work |
If dust is the main complaint and the ducts look reasonably clean, we will say so and point you to the fixes that actually reduce it, covered on our indoor air quality page.
What a whole-home cleaning includes
- Inspection. We look into the supply and return runs, the return plenum and the blower compartment, and check the ducts in the attic or crawlspace for damage before any tools go in.
- Negative pressure. A high-powered vacuum is connected to the duct system so loosened dust is pulled out of the house instead of blown into the rooms.
- Agitation. Brushes and air whips work through each supply and return run, from the register back to the trunk line, to break buildup loose.
- Registers and grilles. They come off and get washed.
- Return side and blower compartment. The return plenum and the area around the blower are vacuumed. If the blower wheel or the indoor coil needs a deeper cleaning, we tell you before doing anything extra.
- Filter. A fresh filter goes in, and we check the filter slot for gaps that let air bypass it.
Older flex duct needs a lighter touch
Flexible duct in an old attic gets brittle, and aggressive brushing can tear its inner liner. We match the tools to the duct type. If a run is torn, crushed or disconnected, we show you: that is a duct repair job, and it comes first, because a leaking duct pulls attic or crawlspace dust right back in and undoes the cleaning.
What affects the price
A whole-home cleaning typically runs $299 to $599. The price depends on how many supply and return runs the home has, whether there is more than one system, how easy the attic or crawlspace is to work in, and how heavy the buildup is. Pest contamination takes more time than ordinary dust. You see the price before work starts.
Keeping ducts clean afterward
- Change the filter on schedule: every one to three months for a standard 1-inch filter, more often with pets or during remodeling.
- Use the most efficient filter your system can move air through. A filter that is too restrictive starves the blower, which can freeze an AC coil or overheat a furnace.
- During sanding or drywall work, turn the system off and cover the return grilles.
- Fix leaky return ducts. A return that leaks in a crawlspace pulls dust from under the house straight into the air you breathe.
- A yearly furnace tune-up or AC tune-up keeps the blower and coil clean, which is where most airflow is lost.
Local notes
Many post-war homes here have ducts running through a crawlspace, where rodents find their way in and leave a mess that cleaning has to deal with. Homes that have been opened up for remodeling often carry fine construction dust in the returns for years afterward. Heating runs mostly from November to March, so the first cold mornings of the season are when built-up dust in the ducts tends to announce itself with a puff from the registers and a dusty smell.