Chimney sweep in Sausalito

A thin layer is nothing to worry about. What is a concern is what a season or two of occasional fires can leave behind: enough of that residue sitting inside the chimney to reach a temperature at which it can catch on its own. Sweeping is the mechanical fix — a brush cut to match the liner’s diameter travels its full length, top to bottom, breaking that buildup free so it can be pulled out with a vacuum instead of sitting there accumulating visit after visit.

Because Marin’s climate stays mild, plenty of local fireplaces get used in bursts through the cooler months rather than burned nightly the way a wood stove elsewhere might be, and that stop-start pattern makes it easy to lose track of how long it has actually been since the last sweep. Creosote does not care whether the fires were daily or occasional — given enough time either way, it reaches a dangerous level, and an annual check is really the only way to know for certain where a given flue stands.

Brushing loose creosote inside a tight flue means that debris has to go somewhere, and left unmanaged it would land on the hearth, the rug, and everything nearby. That is not how this goes. Protection covers the hearth and the path to it before the first brush stroke, and a HEPA vacuum stays sealed to the firebox opening for the entire pass, drawing debris out as it falls instead of letting it settle anywhere in the room. Whatever the space looked like when the appointment started is how it looks when the crew leaves.

NFPA 211 spells out what that covers: everything a technician can see and reach without a camera or a trip onto the roof, meaning the accessible interior of the flue, the firebox, the smoke chamber right above it, and the point where the appliance connects to the chimney. For a chimney in continued, ordinary use with nothing recently changed and no reason to suspect hidden trouble, that depth of check is exactly right.

Where the visual check turns up something a trained eye cannot fully account for — a crack that could run deeper than it appears, or damage traced back to an earthquake or a rough winter storm — that gets flagged plainly, with a Level 2 camera inspection recommended next, rather than guessing at what a flashlight alone cannot show.

A second flue, a wood stove’s own connector pipe, steep roof access at a hillside home in Sausalito or Tiburon, or a floating home out at Waldo Point Harbor can all add time, and that gets flagged before work begins if the job looks bigger than the baseline. What stays fixed regardless is the order things happen in — protect, brush, extract, inspect, report — no matter how many flues are involved or how long it has been since the last visit.