Staining at chimney

Why are these two chimneys so stained?
Two different inspections.



I’s simply call it rust, and have the level 2 done.

your kidding right?

Thanks for the help:roll:

There are very few chimneys that have that much staining. Most have none or very little. It just seems like a disproportional amount. The newer chimney had very heavy creosote build up, which may have had something to do with the rust. Something is different about these two verses 50 others that I have seen in the same time frame. Of course the stove pipe rain cap on the brick chimney isn’t the best choise.

Picture 2 looks like the water is ponding on top of the metal, maybe running down the pipe stove pipe inside the wood cover, and out onto the roof. ??

Thanks for the input Linda. That house was less than 5 years old.
I suspect it could even have to do with the type of wood being burned, that some wood resin/soot may be more corrosive.
Some people burn redwood here, which doesn’t happen at very many other places. We also have madrone, which I understand burns very hot.