pressure washing - roof cleaning

There are dark stains and black streaks on my roof

dark stains and black streaks on asphault roof

Most often it starts small and gradually spreads to rather large black stains. The most common cause of these dark mildew-like stains is actually a form of algae. Most often visible as dark streaks or dark discolored cone shaped areas or patches and shows up first on the north side and in shaded areas.

The most common form of roof algae is Gloeocapsa Magma. The biggest problem with this type of algae stain on your roof is the fact that this algae thrives on the limestone filler used in the asphalt shingles. Over time this can degrade and deteriorate your shingles to the point they crack and curl at the edges. This is accelerated by the black color itself causing a heat build up in the summer and the algae holding in moisture which can cause frost damage in winter weather.

Call for a No Pressure roof cleaning estimate (443) 786-5720

Green algae on roof shingles

In some cases these patches of algae on asphault shingles will be green. Variations in algae color are quite diverse. The roof stains that appear as black streaks, if inspected by an expert can sometimes be identified as blue-green or green algae. Green algae on roof shingles is more common than it seems since some green algae can look like dark patches or black streaks on the roofing surface.

Lichen on a roof surface

Lichens have been described as "dual organisms" because they are symbiotic associations between two entirely different types of microorganism -
lichen on roof shingles
  • a fungus (termed the mycobiont)
  • a green alga or a cyanobacterium (termed the photobiont).
There are many examples of symbiosis in nature, but lichens are unique because they look and behave quite differently from their component organisms. So, lichens are regarded as organisms in their own right and are given generic and species names. However, for taxonomic purposes the names are actually fungal names: lichens are regarded as a special group of fungi - the lichenised fungi.

Crustose lichens produce a flat crust on rock or tree surfaces. When wet the leathery tissue lies flat. The algae component is widely dispersed throughout the organism. Crustose lichens are closely attached to surface and are hard to remove without damaging the roof surface or the lichen itself. As a result it is determined to be better to chemically treat the roof lichen as both fungus and algae. Once the lichen on the roof has been treated, it will let go and fall off the roof on it's own with no surface damage.

Moss on roof shingles can be trouble
moss on roof shingles

Moss on a roof doesn't harm the shingles as much directly but since it is thicker moss weighs more. The excess weight can damage your roof and the thicker moss offers more protection for locked in moisture, molds, mildews and fungi. All these factors combine to lead to a premature replacement.

Moss has a short little dense root structure that hold the moss onto the granules of the roof shingles. Trying to pull or scrape the moss off the roof will most certainly cause damage to the roof surface. As in the case with lichen on the roof it is best to treat the moss on the roof and let it fall off on it's own.

Call for a No Pressure roof cleaning estimate (443) 786-5720

dark stains and black streaks on cedar roof shingles

A cedar roof can have these same stains. On a cedar roof these black streaks are most often simply assumed to be weathering. Usually this is not the case. The algae on a cedar roof is feeding on the bacteria feeding on your cedar shakes which can seem like a good thing but it is just the opposite. The presence of the algae on the roof helps keep moisture in the cedar which can be a breeding ground for bacteria, mold and fungus.

Bacteria, algae and fungus on a cedar roof is far more damaging than on other roof types. Deterioration of the shingles will be accelorated exponentially by the presence of the bioorganisms feeding on them. If your cedar roof is showing signs of dark patches or black streaks

Let us help save your roof before it is too late.

no pressure roof cleaning on cedar roof
Your roof might be costing you. A darkened roof is less reflective and can make your air conditioning system work harder and can cost you more as a result without you even noticing. A roof with black or brown stains or streaks can reduce the value of your home. Protecting the value of your home could be as simple as a quality roof cleaning.

We use a No Pressure roof cleaning method approved by the
Asphalt Roof Manufacturer's Association (ARMA)
and our 5 year warranty ensures you will be happy with your roof.
Call us for a roof cleaning estimate today - (443) 786-5720

Replacing your roof can be very costly. To avoid the expense of a new roof, call us for an estimate to help save your roof with proper pressure washing.

Call for a roof cleaning estimate (443) 786-5720