Black Staining On Roof Sheathing

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.

Black staining on roof sheathing. Mold can form but often it. Note the heavy staining and growth on the plywood. It s been over a year since the leak was fixed and the stain is not going away on it s own. Across the entire eastern half of the country roof shingles tend to grow a species of algae called gloeocapsa magma.

These are commonly seen underneath roof vents plumbing stacks vent hoods and around chimneys. Builders forever looking to save a few bucks began turning toward plywood roof sheathing. Roof algae rarely poses a threat to the health of the roof. It appears in streaks or patches of slime that can be anywhere from blue green to dark black.

The leak was fixed. 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. Below is a more typical example of mold growth. If these isolated spots are seen away from these roof penetrations then the roof may be damaged and leaking.

This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood. It may be difficult to remove the mold stains from sheathing but you can kill. After several years of this there may be dark rings around protruding roofing nails and larger dark spots or areas on the roof sheathing and or exterior gable walls. Natural wood is expensive.

Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green. 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. The original skip sheathing has much less growth. Roof leakage can often be seen as dark black stains concentrated and radiating out from one or more individual locations.

The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black. If your roof is older or in bad shape and needs replaced anyway you may want to invest in these copper infused shingles. Green or black algae stains.