Roof mold – Is it dangerous?

Black "roof mold" on shingles

Black “roof mold” on shingles

Roof Mold.  What is it and is it dangerous?

Is it algae, moss, lichens, fungi, or possible deadly black mold?   We have all heard about deadly black mold growing in homes.  But rest assured, that roof mold is not that rare deadly black mold.

But on houses receiving the right conditions of shade and moisture/humidity, growth of things like algae, moss, or fungi will grow.  In areas with high humidity or frequent rainfall, ensure that your roof is exposed to as much sunlight as possible.

Roof mold or other growths may be merely unsightly; but in more severe cases, can begin destroying shingles.

With algae and some fungal growth, the extent of the damage may only be shingle discoloration.  In warm, humid conditions, certain airborne algae can grow on shingles, leaving “roof mold” that is black or dark-green stains.

Moss or lichens growing on a roof are more likely to hold moisture against the shingles, which can accelerate damage.  Furthermore, if left untreated, their roots or growth structures will eventually penetrate and shorten the life of roof shingles.

Another likely source of damage is the cleaning methods used to combat roof mold or algal growth.

Pressure washing and harsh chemicals can cause rapid granule loss or other shingle degradation.   As is the case with algal treatment, the removal methods for roof mold may cause more damage than the growth itself.  But that does not mean you just leave the growth.  Take preventative measures to combat these growths since roof mold can be destructive.

Tree damage is also a leading cause of of the discoloration attributed to roof mold.

Roof damage from tree branches are a major contributor to needed roof repair or replacement.  Branches that rub against the roof cause granule loss and in some cases cut through the shingles or pull them out of place.  This loss of granule will change the color of the shingles as they are removed.

Unsightly “roof mold” may be the least of your concerns if branches are not trimmed when they come in contact with the roof.  During a storm, heavy winds may cause branches to break off and land on your roof causing major damage to the shingles and decking.

Trim away any overhanging tree branches and maintain your gutters and downspouts so that rainfall will drain quickly.

Confused or want more information?

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