stains on the roof

Ed_26

I would physically inspect the chimney/vent. It may be corroding/rusting etc. If still solid, brush & paint it.

service

stains on roof

my customer called ,she had a new roof put on and now has stains from the metal vent chimney. the house is thirty years old has a newer smith 8 boiler, running well can any thing be done to stop this problem.

Empire_2

Q:.....

What kind of stains are we talking about? White, green mold? can you give us some descriptions....

Mike T.

service

the colors are brown /black the customer went from a thirty year old dark shingles to light gray shingles in the front of the house. the staining starts at the metalvent chimney.

Weezbo

part of the problem could very well have something to do

with the age of the shingles and the erosion process over time due to weather. condensing may be part of the problem also, as a thought.

Paul Fredricks_3

Just a thought

Metal outside oxidizes. With steel it's rust. With the metal on the chimney it's probably a darkish powder. When it rains this washes off onto the roof. Those beautiful new shingles help it to show up. It was probably doing it with the old roof, but no one noticed due to the roofs dark color.

Don't take this as gospel.

JOHN_103

how high is the chimney?and what is your stack temp?

JackFre

I've done a bunch of these

I've represented Dura-vent and Selkirk in the past. Is the 8 oil or gas, btw? I had systems where the all fuel chimney was stainless and the factory provided AL flashings. Someone used a galvanized flashing and the flue gas "residue" over time got down onto the flashing and rusted it out, which in turn stained the roof. Is your flashing AL or galv? Inadequate chimney height on the leeward side can cause occasional downdrafts which can help "push" flue gas byproducts onto the roof.