First and foremost, you should never allow anyone to high pressure clean your roof regardless of the material that is installed. High pressure techniques degrade granules on asphalt shingles shortening their life span. It can exacerbate corrosion on metal roofs and can cause degradation of the concrete on tile roofs.
All roofing systems should be cleaned using low pressure techniques that are specific to the roofing material installed. There are many natural elements that can adhere to any roofing surface, potentially compromising integrity and appearance. Salt, air, direct sunlight, lichens, pollen, mold, and mildew to name just a few.
Asphalt roofing shingles are often discolored by algae and direct sunlight. The most common species in our climate is Gleocapsa magma. These algae typically cause brown to black streaking down your roof often resembling fungus, dirt or even soot. Low pressure techniques using varying strengths of sodium hypochlorite and water cause the algae body to breakdown and are released from the substrate making your asphalt roof looking clean and new.
Metal roofing systems, either painted or galvalume, have their own set of unique issues including water stains, rust stains, and spore deposits. Most metal roof manufacturers recommend a simple cleaning once a year to keep your roof looking clean and bright. For simple cleaning we use a mild detergent solution applied using a low-pressure technique and then thoroughly rinsed with tap water.
Mildew, Algae, or Mold
For roofs that have mildew, algae, or mold we use a sodium hypochlorite solution. For rust stains on metal roofs we have a couple of options depending on the severity of the stains. For mild rust we will use a mild abrasive cleaner applied using a non-abrasive pad rinsed with water. For more severe rust we apply a vinegar solution with a rag then rinsed with water.
Tile roof systems require is a hybrid of both asphalt and metal roof cleaning techniques. We typically use a mixture of mild detergent and /or sodium hypochlorite solution.
On all roofing systems, our goal is to never overuse or abuse cleaning agents in any circumstance. If there is a substance we cannot get off using our normal tested procedures we will under all circumstances call the manufacturer for their suggestion. We will never use any product that will void your warranty.