· 5 min read · by the Remarkable team
How often should your chimney be cleaned?
Ask ten neighbors and you'll get ten answers, from "every year" to "never, apparently." Here's the real answer — the one written into the national fire code — and how to apply it to your own fireplace.
The short answer: inspect yearly, clean as needed
The standard that governs chimney care in the United States — NFPA 211, from the National Fire Protection Association — says it plainly: chimneys, fireplaces, and vents should be inspected at least once a year, and cleaned whenever deposits are found. The Chimney Safety Institute of America (CSIA) adds a concrete trigger: sweep when creosote reaches 1/8 inch of buildup, sooner if it's the shiny, tar-like glaze variety.
Notice the order of operations. The schedule isn't really about cleaning — it's about looking. An annual inspection is cheap insurance; the sweep happens only when the flue actually needs it.
A rule of thumb by how much you burn
Creosote accumulates with every fire, so frequency tracks usage:
- A few fires a month, seasonally — an annual inspection with cleaning as needed is usually enough. This is most SF households.
- Several fires a week all winter — plan on a full sweep every year, sometimes mid-season. Roughly speaking, a cord of wood burned is a good prompt to check the flue.
- Wood stove as primary heat — inspect and clean at least annually, and watch for faster buildup if you damp the stove down overnight.
- Rarely or never burn — you still want the annual look. Birds, storms, masonry movement, and water damage don't care how often you light fires.
Why San Francisco changes the math
Two local quirks push SF chimneys toward the cautious end of the schedule. First, the marine layer: fog-damp air keeps flues moist, and moisture turns creosote acidic — it eats mortar joints and rusts dampers even in the off-season. Second, the housing stock: thousands of pre-1940 homes vent through original, unlined brick flues, where there's no clay tile protecting the masonry. Deposits sit directly on brick and mortar, so buildup does more damage per season than it would in a modern lined chimney.
Cool evenings also mean many households burn short, smoldering fires — exactly the kind that produce the most creosote per log. If that's your pattern, err toward yearly cleaning.
Gas fireplaces aren't exempt
Gas burns clean, but the venting still collects debris, gaskets fail, and coastal air corrodes termination caps. NFPA 211's annual inspection applies to gas appliances too — our fireplace and firebox service covers them alongside wood-burners.
The takeaway
Put one reminder in your calendar: book the inspection before the first fire of the season — late summer and early fall are the easiest times to schedule. If the camera finds 1/8 inch of creosote, sweep. If it doesn't, you've spent very little to know your chimney is safe.
Not sure where your flue stands? Call (650) 722-5502 — we'll ask a few questions and tell you honestly whether it's time.