Outdoor chimney brick discoloration

[McGinley]

I have a wood stove insert in my living room. I've stoked a number of hot fires this past winter. I was just sitting in my yard when I noticed this brick discoloration on my chimney directly on the other side of the insert. I'm not planning on any more fires this year, but I certainly would like to know what's going on before I build fires next winter.

The insert is a Harman.

 

[bholler]

I have a wood stove insert in my living room. I've stoked a number of hot fires this past winter. I was just sitting in my yard when I noticed this brick discoloration on my chimney directly on the other side of the insert. I'm not planning on any more fires this year, but I certainly would like to know what's going on before I build fires next winter.

The insert is a Harman.View attachment 337659

Looks like mildew to me

 

[begreen]

Spray a little bleach on an area to see if it removes it. If so, it likely confirms bholler's thought.
Open the cleanout door and looks for moisture accumulation. The top cap or crown may be leaking.

 

[moresnow]

Looks related to your fascia and gutter growth. Shaded area from the fence. Likely on the north side of the house. My guess.

 

[stovelark]

It does look related to gutter staining area, I'd think it'd clean up pretty easily.

 

[vatmark]

That is mildew. Does not look wood stove related. Get it cleaned off and the spray that area with Wet-n-Forget. Or Spray with Wet-n-Forget and leave it. It will take a while but should clear up.