ROOF STAINING CAUSED BY BURNING HIGH SULFER #2 STOVE OIL
Soot can cause black and brown roof stains below and around chimneys.
even when there is little or no evidence of staining on other areas of the roof.
Soot is the fine, black powder by-product of combustion.
soot will wash down the slope of the roof and leave a trail of discoloration across the shingles.
Soot is also very corrosive to metal roofing.
Burning #1 stove oil instead of #2 will help greatly to prevent this kind of staining and corrosion.
Also having your furnace tuned up can help if it is burning dirty.