Stained by algae or not, roofs are cleaned using any of three common methods, each of which has its own set of pros and cons. These methods are, pressure washing, and the application of solutions containing either, chlorine bleach or sodium hydroxide. When performed correctly and only once, these techniques clean roofs effectively without significant adverse effects. The problem is, they usually have to be repeated every six to 18 months to maintain cleanliness.

Chlorine Solution Washes: Chlorine bleach solution application requires a lot less rinsing than the two other methods, thereby allowing a cleaning procedure of shorter duration. One good consequence of a quicker process is less wear and tear for the roof. However, chlorine can be toxic to some people and plants, so care should be exercised to protect employees or residents, as well as the property itself, from spray runoffs. Asphalt shingle roofs are particularly well adapted to this type of cleaning.

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Sodium Hydroxide-Based Cleaning: This type of roof cleaning method can be very effective at degreasing roofs. However, this cleaning method takes a much longer time than chlorine bleach washing because the sodium hydroxide needs to be thoroughly rinsed. As a consequence, a roof becomes more at risk for being damaged. A force of 100 psi is enough to wash away the cleaning solution on asphalt shingle roofs, but the force is enough to cause some asphalt granules to get washed away during the rinsing process. Advertisements claim that sodium hydroxide is safe to use, but it can actually be toxic. Thus, make sure that the solution does not run off or come into contact with people, plants and anything in the surrounding area during the application and rinsing process. In addition, sodium hydroxide is corrosive so any residues left can damage the roof, particularly those that are made of asphalt shingles.

Pressure Washing: If you have a concrete, barrel tile or metal roof, you can clean it by power washing. Power washing does not involve the use of chemicals, which makes power washing an environment-friendly method of roof cleaning. However, power washing is rather time consuming and can put more strain on the roof. If you have coated roof tiles, the thin layer of coloring can be easily washed away by power washing. If you have a concrete roof, power washing will bring out the concrete's natural gray color, and this could mean that you will have to paint or stain the roof afterwards.

How To Clean Your Roof - The Right Way

David Lee is an expert on pressure washing and concrete cleaning. For more information see Atlanta pressure washing or Atlanta concrete cleaning or Atlanta roof cleaning.