Found out creosote buildup is actually flammable at way lower temps than I thought

Was reading through some old NFPA reports last night and saw a stat that really caught me off guard. Turns out third stage creosote can ignite at just 200 degrees Fahrenheit. I always figured it needed a hot chimney fire to go up. Found that detail in the 2023 NFPA 211 handbook. Makes me wonder how many of us are checking for that thick glaze stuff during routine sweeps. Have any of you seen it catch at lower temps than expected?

3 comments

3 Comments

sage_green1mo ago

Have you ever run a wire brush over that shiny black stuff and watched it just peel off in sheets? That's third stage creosote. I had a customer last winter who thought he was fine because he only burned seasoned oak. His flue had that thick glaze and the whole thing lit off when he relit a dying fire. The funny thing is it didn't even need a big flame, just a few random embers popping up did the trick. The NFPA 211 standard is no joke about keeping that plastic looking layer off the walls.

-3

jasonallen1mo ago

Read an article a while back about how that shiny creosote is basically a fire waiting to happen. The guy wrote that even a few embers can set it off since it burns way hotter than regular soot. Crazy how it gets that hard plastic look too.

the_simon1mo ago

NFPA 211 says a lot of things. I've seen flues with that glaze that looked scary for years and never had a problem. My dad's cabin has a stove that's been running since the 80s with the same pipe. We cleaned it once maybe ten years ago. Nothing ever caught fire. I'm not saying it's safe, but people act like one spark and your house is gone. Reality is most of those horror stories are from folks who let it build up for a decade or ran a bad stove.