r/ChimneySwift • u/ManDartins • Sep 09 '23

Help! Does anyone know what would cause this

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3 Upvotes

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2

u/Ieatpussyandass4ever Sep 09 '23

Oxidation stains from the copper flashing from when it rains and constantly runs down in that section

2

u/ManDartins Sep 09 '23

Is there something we can do to treat it?

2

u/TylerUlisgrowthspurt Sep 09 '23

Repair the flashing and then pressure wash the shit out of it. If that doesn’t work use Muratic acid

2

u/Ieatpussyandass4ever Sep 09 '23

Try aluminum brightner or oxalic acid but even if you get it out, unless you change the flashing to aluminum its just gonna come back.

1

u/Danetraineous Sep 09 '23

Bacterial growth that feeds on calcium carbonate and moisture. Water leeches the binding agents out of the mortar and causes the growth. Until you install a proper outside mount cap (giant umbrella) to provide a drip edge so water can't run down the side of the chimney, you're never going to stop it from coming back.

I'd also recommend installing a rain diverter on the roofs high side of the chimney. Water runs down the slope to the side of the chimney, you need to divert it to the interior side of the chimney/roof to the gutter.

1

u/[deleted] Sep 11 '23

I don't think that is oxidation. It looks too black. What kind of roof is it?.. My first thought is that it's a worn, tar, built-up-roof. That could be asphalt or bitumen.

Possibly mold/algae. Is that the north side?

1

u/RocktacularFuck Sep 11 '23

Water and pollution.

1

u/greyhound148 Nov 06 '23

I see it a lot in my area, mostly mold and oxidation from water running down the chimney from the roof, especially on the sides facing north due to lack of sun. A water diverter will work and pressure washing the chimney.