Granules, the sand like element that is keeping the rain from destroying your home by way of the roof shingle. Granules are also the reason you should never pressure wash your roof. These delicate granules are held to your roof shingle, layer upon layer by a form of glue. A simple walk on your roof removes some granules, just imagine the damage a pressure washer does to it.
A.R.M.A [American Roofing Manufacturers Association] represents a majority of roofing manufacturers in North America. Their primary concern has been to find common ground on asphalt shingle manufacturing and the process of maintenance.
Their bulletin on the proper method of roof cleaning 1 is commonly, cited by roof cleaning companies. The three main points of the bulletin were:
- Never power-wash asphalt shingles.
- Only chemical cleaning can temporary remove and combat algae stains
- The only long-lasting way to combat algae is to have AR [algae resistant shingles] installed.
Unfortunately, although Algae resistant shingles are reaching their teen years in service, not very homes being built to this day have them installed due to the higher cost of the shingle compared to a regular asphalt shingle. RCI-online, stated that up to 50% of all roof replacements are done for cosmetic reasons instead of from leakage or wear. 2