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Black staining on roof sheathing.
I had a roof leak a year or more ago.
Builders forever looking to save a few bucks began turning toward plywood roof sheathing.
Roof leakage can often be seen as dark black stains concentrated and radiating out from one or more individual locations.
Below is a more typical example of mold growth.
It appears in streaks or patches of slime that can be anywhere from blue green to dark black.
These are commonly seen underneath roof vents plumbing stacks vent hoods and around chimneys.
However i was in the attic the other day and noticed the underside of the roof sheathing plywood at the old leak area has some black staining where the plywood got wet from the leak.
Note the heavy staining and growth on the plywood.
It was a result of bad flashing at the chimney pentration.
Green or black algae stains.
It s been over a year since the leak was fixed and the stain is not going away on it s own.
This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood.
Natural wood is expensive.
Here is a diagnostic guide to types of stains and staining materials found on roof surfaces black red green brown or other coloured stains on asphalt roof shingles or on other roofing materials need first an accurate diagnosis of the stain cause and then proper steps to remove the stain or to prevent future staining on roof shingles surfaces.
The original skip sheathing has much less growth.
Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green.
The leak was fixed.
Replacing the shingles on your roof just because you have black stains is not necessary however and you should be suspicious of any roofer that suggests roof shingle replacement as the only solution to your algae problem.
Roof algae rarely poses a threat to the health of the roof.
It may be difficult to remove the mold stains from sheathing but you can kill.
Across the entire eastern half of the country roof shingles tend to grow a species of algae called gloeocapsa magma.
When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black.
Mold can form but often it.