Guest User
Our metal rooof is 10 years old and we have black stains around a couple vents. Why? How do you remove them and do we need more ventilation.
Todd Miller
Isaiah Industries, Inc.
They probably can be cleaned with a light detergent or trisodium phosphate. Usually when I have seen this it is because there is a lot of moisture existing those vents. That moisture then has a tendency to fall, condensing on the roof. Keeping the roof regularly moist and damp eventually allows biological growth and hence the black marks. Adding additional exhaust vents to the roof in order to disperse the moisture, or finding other ways to reduce the moisture in the attic, should be helpful.
Eric Novotny
An informed customer is the Best Customer!
+1 TSP works well and is mild. Check with the metal manufacturer for compatibility just to make sure you are staying inside their guidelines.

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