Roof Cleaning - Making Your Old Roof Look Like New!

Whatever the main reason, it's in your best interest to know what your options are when it comes to having a roof replaced. A quality roof should last more than 30 years with proper care and maintenance. Unfortunately, many roofs here in norfolk (and increasingly throughout the U.S.) are unnecessarily stressed during cleaning, which significantly reduces the life expectancy of the roof. Repetitive roof cleaning has some pitfalls that every homeowner, property manager and professional roof cleaner should be aware of to avoid property damage, unnecessary repair costs and premature roof replacement.

WHY DID THE ROOF TURN BLACK?

The black streaks typically found on homes in areas where moisture settles on the shingles are not caused by mold or fungus, but by roof algae. 3M scientists have identified the most common form as Gloeocapsa magma. The algae spores are carried by the wind, which is why so many homes in the neighborhood can be affected by this problem. In the last 20 years, this particular strain of algae has become more resilient and therefore has been able to move to less humid environments than in the past. And in areas where it is traditionally found, the stains appear earlier, are more severe and settle on more roofs.

HOW CAN IT BE CLEANED?

Typical roof cleaning methods are either pressure washing or chemical solutions using chlorine bleach or sodium hydroxide. When used properly, these methods clean the roof with minimal adverse effects - however, the effect can be very temporary and usually needs to be repeated every 6-18 months to maintain the roof's appearance.

WHAT IS THE BEST CLEANING METHOD?

Each method has its advantages and disadvantages.

A solution of chlorine and water can be used, followed by a thorough rinse. Since chlorine can be toxic to people and plants, care should be taken to protect employees and surrounding properties from splashes and runoff. The benefits of using chlorine include a much faster cleaning process and minimal rinsing compared to other methods. This results in much less wear and tear on the roof - especially asphalt shingle roofs.

Sodium hydroxide-based cleaners are generally touted as safer for landscaping, but sodium hydroxide is corrosive and very toxic, and care should also be taken to protect employees and surrounding property. Sodium hydroxide is also a very effective degreasing agent. So a high sodium hydroxide content in a cleaning product can cause damage to an asphalt shingle roof that may be irreversible. These products typically require much more frequent rinsing than the chlorine method.

Not only is the rinsing process time consuming, but it can also damage the roof if not done correctly. A good quality sodium hydroxide-based product should not require more than 100 psi to effectively rinse an asphalt shingle roof, and even then some granule loss should be expected.

Pressure washing is an option that should only be used on concrete, tile or metal roofs. Pressure cleaning has the advantage of not requiring chemicals, which eliminates some of the cost - except for the concerns about landscaping and chemical exposure. The disadvantage of pressure cleaning is that it is very time consuming and exerts a tremendous amount of force on a surface that is not actually designed for it. Also, repeated pressure washing can wear away the surface of some tiles that are only covered by a thin layer of paint. When this happens, the gray concrete color begins to show through and the roof needs to be stained or painted.

THESE METHODS ARE NOT LONG-TERM SOLUTIONS.

While these methods are relatively safe and effective when done properly, they will cause the roof to age prematurely if used repeatedly. The natural erosion that occurs over time from the basic forces of heat, cold, wind, and rain is enough to weaken most roofs to the point where annual inspections and minor repairs are required to avoid significant repair costs. However, when the roof is repeatedly exposed to high pressure or harsh chemicals, the aging of the roof structure is greatly accelerated. With repeated cleaning, roof tiles are more likely to shift, slip or break, and asphalt shingles become brittle and crack.