When to have your chimney swept (and the signs you waited too long)

Creosote builds on the inside of a flue every time you burn wood. Softwood (which is most of the firewood sold around Puget Sound) and slow, smoldering fires build it fastest. An eighth of an inch of creosote is enough to sustain a chimney fire, and a chimney fire can crack a liner or spread to the framing.

Annual

The NFPA recommends an annual inspection for any chimney in regular use, and sweeping when build-up warrants it. If you burn through the winter, plan on a sweep every fall before the first fire.

Warning signs

Smoke coming back into the room. A strong smoky smell from the fireplace when it is not lit, especially in summer humidity. Black flakes falling into the firebox. A fire that is hard to get going or burns poorly. Any of these means a blockage or heavy build-up and the chimney should not be used until it is swept.

What a sweep includes

Mechanical brushing of the flue, cleaning the smoke shelf and damper, cleaning the firebox, a visual inspection for damage, and a note of what we found. Full containment so nothing enters the room.