I can see creosote on the chimney and cap. It definitely needs to be cleaned but its not horrendous. Is the staining being cuased by creosote or jsut the rust of the cap and pipe? I’ve never seen a stain like this without the cap or pipe being HEAVILY rusted. The cap and pipe aren’t recently replaced. Is this amount of staining a problem? I’d love your thoughts
1: Stain Cause, poor drafting. Poor wood species for burning. Soot, Smoke & Creosote stains. Low combustion temperature.
2: Chimney lacks a proper crown with a capillary break.
3: Suspect: Flue Liner condition.
4: Ask if there was a previous chimney fire.
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Looks like the cap has been replaced. The old one is probably what is all over the roof. 
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My thoughts exactly.
It’s cosmetic more than anything. I re-created the problem on my own shop to show you, lol. Mine was caused by burning wet and non-seasoned wood, as well as burning at low temps for too long over time.
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Air tight burning stoves will to it everytime.
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It’s missing the hub cap I mean rain cap 
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According to this chimney sweep, red stains are caused by the chimney cap / flue rusting and burning unseasoned wood creates black stains (creosote). I am wondering if anyone here can verify?
The flue cap makes red, chimney cap makes red if it is metal. Concrete chimney cap makes black from organic material from it;s alkalinity. Green is from copper. And you will see no mold on the roof below. Light vs dark shingles etc.
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