Is it better to power wash or scrape the mold off my roof?

The question of whether to power wash or scrape mold off your roof is simple: both need to work together in order get your roof looking and functioning at its best once again.


The purpose of the clean-up process is to eliminate mold and fungal growth and to remove contaminated materials. Simply killing the mold with a chemical is not enough. The mold must be removed since the chemicals and proteins, which cause a reaction in humans, are still present, even in dead mold.

Removing mold from the roof of a house is not only important in the prevention of a number of serious health conditions, but also gives an overall better look to the house. While there are a number of ways to remove roof mold, some of the best include using solutions of chlorine bleach and copper sulfate. In addition, preventing the growth of roof mold to begin with will eliminate the need to get rid of it.

Many homeowners are surprised to discover that once-clean asphalt shingles are slowly being covered with a form of roof mold or mildew that appears as a light discoloration and spreads down the roof toward the gutters. Black roof stains are caused by a form of algae that has been around for years, typically found in the woods on the north side of trees or on exposed rocks. But now this black algae is termed a roof shingle algae because of the annoying discoloration that appears on this roofing material. The roof algae actually feed on crushed limestone that is present in shingles from most asphalt roof manufacturers. The algae are spread by wind and animals from roof to roof and are almost impossible to prevent.

The good news is this: Yes, roof stain removal is possible using a professional roof cleaning service. Always choose a business that has experience with appropriate shingle cleaning techniques and products, and one which uses the proper pressure. Our unmatched skill and years of experience will typically result in more complete removal of stains.

High pressure jet washing or scraping of roofs is not recommended by professionals as both methods remove granules from the protective coating. Each time these aggressive cleaning methods are used, tiles are made more porous. When granules have been removed, the roof stays damp, encouraging fungal growth to return. In addition, spores are not killed by these methods, meaning in a short time the problem will be worse than before.

We use the recommended gentle approach. This will produce better long term results and does no harm to any type of roof surface. Excess mold is safely removed by brushes. Then the roof is carefully rinsed at low pressure with high performance roof cleaning solution. The pressure used is no stronger than rainfall, which will not cause damage to tiles or slate.

Over a period of a few months, all growth is slowly broken down and will fall into the gutters. As all spores are killed, growth will take much longer to return. It is difficult to stop the force of Mother Nature, but the right prevention and remediation techniques will keep it at by, allowing you to enjoy a safe and secure roof for many years.


Call Cedar Roofs NW for roof mold removal in:
Oregon: Portland, Lake Oswego, West Linn, Beaverton, Tigard, Tualatin, Sherwood, Wilsonville, Gresham, Oregon City, and Clackamas. Washington: Vancouver.