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Is my chimney due for a sweep?
What you burn, how much, and what you have noticed decide it — not the calendar. Answer a few questions and get a straight answer: due now, due before the burning season, or just keep to the yearly inspection.
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How this works
Inspection every year
NFPA 211, the national fire-safety standard for chimneys, recommends that chimneys, fireplaces and vents are inspected at least once a year. That holds for every fuel, gas included.
Sweeping when the buildup says so
The Chimney Safety Institute of America's guidance is to sweep when there is about 1/8 inch of sooty buildup in the flue, or sooner if there is glazed creosote. The tool estimates how fast you are likely to get there.
What speeds it up
How much you burn, wet or unseasoned wood, and slow smouldering fires all add creosote faster. Warning signs override everything else and move the answer to before the next fire.
This is a rule of thumb, not an inspection. Every chimney is different, and the technician confirms what yours needs on site. Your answers stay in your browser.
Questions people ask
- How often should a chimney be swept?
- There is no fixed calendar. NFPA 211 recommends an inspection at least once a year, and the Chimney Safety Institute of America's guidance is to sweep when the flue has about 1/8 inch of sooty buildup — or sooner if there is glazed creosote. Someone burning most days in winter may need it more than once a season; someone with a few fires a year may go longer between sweeps, but still needs the yearly inspection.
- Does a gas fireplace need to be swept?
- Gas does not make creosote, so it rarely needs sweeping in the wood-burning sense. It still needs the yearly inspection. Nests, fallen debris and corrosion can block a gas vent, and that vent is what carries carbon monoxide out of the house.
- How can I tell if there is too much creosote?
- From the room, the clues are black flakes or crumbs falling into the firebox, a smoky or tarry smell, and a fire that is slow to draw. The actual measurement — how thick the buildup is and whether any of it is glazed — is something the technician does from inside the flue. Please don't climb onto the roof or put your head into the fireplace to look.
- Do creosote sweeping logs replace a chimney sweep?
- No. They can loosen some deposits, but they do not remove what is on the flue walls and they do not inspect anything. They are not a substitute for a sweep and an inspection.
- Does softwood cause more creosote than hardwood?
- Moisture matters far more than species. Dry, seasoned softwood is fine to burn — it just burns faster. Wet or unseasoned wood of any kind burns cooler and leaves much more creosote. Wood is generally treated as seasoned once its moisture is 20% or less.
- When is the best time of year to book a sweep?
- Many people book in spring or summer, once the burning season is over. The winter's buildup is cleared instead of sitting in the flue all year, and any repair the inspection turns up can be done before you need the fireplace again. If you have any of the warning signs, don't wait for the season — have it looked at before the next fire.
Not sure which kind of inspection to ask for? Take the inspection level quiz. Never had it swept at all? Read what that means.
Book the sweep and inspection
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