Many Floridians who have come from the north are surprised by the idea of cleaning the roof, and even more so by the fact that many communities here in Florida require it. Reasons for cleanliness include aesthetics, property values, energy efficiency, and increased longevity of the roof.
Whatever the main reason, if it is to be performed, it is in your best interest to know what options are available to you. A quality roof should last more than 30 years if it is cared for and maintained properly. Unfortunately, many roofs here in Florida (and increasingly in the US) are subject to unnecessary stress while cleaning greatly reduces the life expectancy of the roof. Repeated roof cleaning comes with certain pitfalls that every homeowner, property manager, and professional cleaner should know about to avoid property damage, unnecessary repair costs, and premature roof replacement.
WHY HAS THE ROOF TURNED BLACK?
The black streaks typically found on homes in areas where moisture settles on shingles is not caused by mold or mildew; it’s the algae on the roof. 3M scientists have identified the most common form as Gloeocapsa Magma. Algae spores are carried by the wind, which is why so many neighborhood homes can end up with this problem. Over the past 20 years, this particular strain of algae has become more resistant and thus has been able to migrate to less humid environments than in the past. And in the areas where it has traditionally been found, the stain is appearing earlier, is more severe and settles on a greater number of ceilings.
HOW CAN IT BE CLEANED?
Typical roof cleaning methods involve pressure cleaning or chemical solutions containing chlorine bleach or sodium hydroxide. If used correctly, these methods will clean the ceiling with minimal adverse impact, but the effects can be very temporary and will generally need to be repeated every 6 to 18 months to maintain the appearance of the ceiling.
WHAT IS THE BEST CLEANING METHOD?
Each method has its advantages and disadvantages.
A bleach and water solution can be used followed by a thorough rinse. Of course, since chlorine can be toxic to people and plants, proper care must be taken to protect employees and surrounding property from overspray and runoff. The benefits of using bleach include a much faster cleaning process and minimal rinsing compared to other methods. This translates to much less wear and tear on the roof, especially on asphalt shingle roofs.
Sodium hydroxide based cleaners are generally advertised as safer for landscaping, but sodium hydroxide is caustic, very toxic, and care must also be taken to protect employees and surrounding property. Sodium hydroxide is also a very effective degreaser. Therefore, high levels of sodium hydroxide in a cleaning product can damage an asphalt shingle roof which can be irreversible. These products generally require much more rinsing than the bleach method. Not only is the rinsing process time consuming, it can also damage the ceiling if not done properly. A quality sodium hydroxide based product should not require more than 100 psi to effectively flush an asphalt shingle roof and even then some granule loss should be expected.
Pressure cleaning is an option that should only be used on concrete, barrel shingles, or metal ceilings. Pressure cleaning has the advantage of not requiring chemicals, which eliminates some of the cost, in addition to the hassle of landscaping and chemical exposure. The downside to pressure cleaning is that it is time consuming and exerts tremendous force on a surface that is not really designed to handle it. Also, repeated pressure cleaning can abrade the surface of some tiles that are only covered by a thin layer of colorant. When this happens, the gray color of the concrete begins to show and the ceiling needs to be stained or painted.
THESIS METHODS ARE NOT LONG-TERM SOLUTIONS.
While these methods are relatively safe and effective when done correctly, repeated use will lead to premature aging of the ceiling. The natural erosion that occurs on the tie due to the basic forces of heat, cold, wind and rain alone is enough to weaken most roofs to the point where annual inspections and minor repairs are necessary to avoid significant repair costs. But when the roof is repeatedly subjected to high pressure or harsh chemicals, the aging of the roof structure is significantly accelerated. With repeated cleaning, tiles are more likely to move, slip or break and asphalt shingles to become brittle and crack. When this happens, there is a greater chance of breaking the roof membrane simply by walking on the roof. Once gaps are created in the roof and subsequent blast cleaning or chemical cleaning is carried out, these gaps provide a path for water or caustic solutions to the roof membrane and increase the potential for costly roof leaks.
WHAT IS THE ALTERNATIVE?
A proper preventive maintenance program will eliminate the need for future cleaning and the possibility of accompanying damage. Preventing the reappearance of algae growth will require a light spray of chlorine and water or an algae prevention product.
Most quality algaecides will last approximately 6 to 12 months before the product needs to be reapplied. Obviously, the longer the time frame, the better your chances of minimizing unnecessary roof damage. Prevention programs should be carried out together with neighbors whenever possible, and many can be implemented without the need to walk on the roof.
An important point about algaecides: Algaecide products are regulated at both the state and federal levels. Any algaecide product used on a roof requires EPA registration as a pesticide or biocide and approval for use on a roof. Contractors who violate the law in this regard face fines of up to $ 10,000. by occurrence.