Black Staining On Roof Sheathing

If these isolated spots are seen away from these roof penetrations then the roof may be damaged and leaking.

Black staining on roof sheathing.

I had a roof leak a year or more ago. Across the entire eastern half of the country roof shingles tend to grow a species of algae called gloeocapsa magma. It was a result of bad flashing at the chimney pentration. The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black.

The original skip sheathing has much less growth. 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. Mold can form but often it. This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood.

Roof leakage can often be seen as dark black stains concentrated and radiating out from one or more individual locations. Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green. Builders forever looking to save a few bucks began turning toward plywood roof sheathing. 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.

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. Natural wood is expensive. It may be difficult to remove the mold stains from sheathing but you can kill. Below is a more typical example of mold growth.

When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black. Note the heavy staining and growth on the plywood. 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. Roof algae rarely poses a threat to the health of the roof.

It s been over a year since the leak was fixed and the stain is not going away on it s own. The leak was fixed. Green or black algae stains.