Dirty Streaked Roof?

Dirty Streaked Roof - Roof Cleaning Northern Virginia

What Causes Dark Roof Stains?

Black or very dark roof stains are caused by a hardy type of algae, Gloeocapsa magma (often referred to as blue-green algae), which grows on the roof and feeds on the limestone filler in asphalt shingles.

Often the algae originates in standing water as well as in lakes and ponds. Wind, birds and other wildlife carry the algae spores to roofs from the water sources and then from roof to roof.

Most of the stains begin on the north facing side of the roof where the lack of sun keeps the roof from drying out completely. The algae normally grows for quite some time before stains are noticed. As the algae grows, it holds more moisture on the roof thus accelerating the growth process.

Health Benefits to Roof Cleaning

Having your roof cleaned not only improves curb appeal, it adds tremendous value to your homes overall worth. Removing algae, moss and lichen from your roof shingles also carries health benefits. The possibility of vent contamination will decrease and air quality inside the home will be improved.

Improve Your Curb Appeal

Today’s housing market is saturated with homes for sale. Having your roof cleaned is a great, inexpensive way to make a lasting first impression with potential buyers.

Let us make your home stand out from the others. Neighbors and house-hunters will notice the dramatic improvement we are able to make to the exterior of your home.

Remarkable Results!

We are finished when you are completely satisfied with the results. Our results are always the same, “Remarkable”.

We offer over-the-phone estimates or on-site estimates any day of the week at no cost.

> Contact Smart Wash today

Algae on Roof


Algae on a roof surface appears as a thin green coating. The presence of algae on the roof is an indicator that this roof area is in a shaded spot where you may want to be alert for development of moss, lichen or other roof problems.

Moss on Roof


Moss will grow in areas of high humidity and shade. Moss is more than a cosmetic issue on asphalt shingles. Holding moisture against the roof surface speed the wear of the asphalt shingle surface in freezing climates by increasing frost damage to the mineral granule coating on the shingles.

Lichen Colonies on Roof


Lichens are a fungus, and will grow in areas of high humidity and shade, lichen growth on roofs creates a dull and dirty appearance, while eventually causing severe damage to the roof, it is extremely unattractive and will reduce the value of your home