You may have what some refer to as 'black algae' present on your roof. This is not actually algae (which is more like a plant) but rather a bacteria that survives off the materials that make up your roof. This bacteria can transfer to other surrounding roofs if not treated quickly. We have the equipment and the expertise to rid your roof of these uninvited diners.
Every roof has a unique set of factors effecting its life and its appearance. The climate, environment and geography of your area all play into the condition your roof is in. Typically a roof can go 2-4 years without needing a cleaning.
Let us know what type of roof you have and what condition its in. Are there leaves or large branches. Are there green black or yellow patches? Does your roof have gutters on the perimeter? We would he happy to provide a quick quote and schedule an appointment to clean your roof.