Most areas of the country are favorable for mildew, algae, and moss growth. These organic materials can grown on almost anything, including glass, stucco, siding, driveways, and roofing products, such as concrete tiles. While they do not grow directly on the tile, they do grow on the dust and other materials that settle there, giving an overall dirty appearance to your roof. After several cycles of heat, moisture, and light, the organic spores grow and spread. Many environmental variables affect the potential for this organic growth, such as location, sun exposure, and the amount of trees, canals, and lakes surrounding your property.
While there is nothing you can do to prevent organic growth on your tiles, it can be removed, and the tiles treated. Because walking on a wet tile roof can be dangerous, PRCA recommends that homeowners use a professional roof cleaning company. Our contractors adhere to the tile manufacturers recommendations and use a Non-Pressure cleaning method.
What is the Non-Pressure Cleaning Method?
The Non-Pressure cleaning method uses a chemical treatment that absorbs into the pores of the tiles. This is the most effective cleaning process that should keep your tiles clean for 3 to 5 years. Most tile manufacturers endorse this cleaning method in their technical publications.
Does the roof cleaner have to use a chemical treatment?
Technically, tile roofs can be cleaned without the use of chemicals, but those methods tend to require heavy foot traffic, which can crack or break the tiles. Concrete and clay tiles are extremely fragile, and most tile manufacturers recommend keeping foot traffic on them to a minimum. Besides, if the tiles are cracked or broken during cleaning, you may never know, unless you climb up and inspect the roof yourself. It is possible that a contractor will accidentally break some tiles, which will be costly to replace, and can potentially void your warranty. This is why it is best to hire a professional roof cleaner who can clean your roof with minimal foot traffic. In some cases, foot traffic is not needed and the roof can easily be cleaned from a ladder. For larger homes, the roof cleaner may use a lift for safety and to avoid unnecessary foot traffic.
Why can’t the roof cleaner just use a pressure washer?
Tile roofs should never be cleaned with a pressure washer, or any method that requires pressure. Most contractors use a high power pressure washer (around 3000 to 4000 psi) which will erode the tiles’ surface and edges, causing small pieces of tile to break off. In some instances, the pressure can be so intense that that it causes the tiles to bleed. This is when the dye or pigment used to color the tile is literally washed away. You will see evidence of bleeding tiles when the run-off water has a color or tint. Once the tiles are dry they will often have a lighter appearance and may look faded or chalky. If the contractor uses a lower psi washer, it will not have the capability to give your tile roof a thorough cleaning. This means the organic material will still be present, and will continue to spread. Besides excessive or insufficient psi, there are a number of other problems with using a pressure washer. For example, the motion used to move the cleaner up and down causes it to drag and break the edges of the tiles. Also, the pressure can cause water to be jetted into areas that normal rainfall may not penetrate, causing a leak and water damage to interior spaces. For these reasons, PRCA recommends you hire a reputable and professional roof cleaner who uses manufacturer approved cleaning methods to insure the longevity of your tile roof.