Most people don’t realize that dirty roofs have a short life span. The before photo (above) is on many roofs. The evidence of damage is shown below in this before/after photo. Notice the loss of roof granules in the lower portion of the photo. This clean portion once was dirty and the cleaning of this roof exposed the damage. These granules protect the integrity of a roof shingle and loos of granules will lead to the need to replace your roof shingles.