The short answer to your question is, “No.” Pressure washing an asphalt composite roof is a very bad idea that can damage the integrity of your roof and increase the future risk of interior damage caused by leaks.
To help you better understand the problems that pressure washing could cause, an explanation of how an asphalt composite shingle is constructed might be helpful.
• The manufacturer starts with a woven fiberglass mat that is normally about one-eighth inch thick. The mat serves as the “backbone” of the shingle.
• Hot asphalt is applied to both sides of the fiberglass mat.
• Before the asphalt cools, granules are embedded into the asphalt. The granules are typically a standardized mix of several different colors that have been selected to create the desired shingle color.
The granules on your shingles are extremely important. The main function of the granules is to protect the asphalt from harmful UV radiation that can make the asphalt brittle and dry. Brittle shingles are more easily cracked, which in turn can lead to leaks. In addition, the granules give your roof its color. Granule loss can leave bald spots that detract from the appearance of your home.
Although all shingles will experience granule loss from hail, high winds or age, pressure washing has a tendency to “blast” them off in great numbers. Pressure washing can do more than just remove the granules — it can also crack or strip the asphalt that gives shingles their waterproofing.
The primary reason most people give for wanting to pressure wash their shingles is that they have moss, algae or fungi growing on their roof. It is true that these growths can damage your shingles and cause your roof to fail. However, the best option is to have these problems treated by a roofing professional who can offer a long-lasting solution.
The removal of moss and debris is just one of the many services offered by Alpha Roofing. We have over three decades of industry experience and offer a wide variety of roofing services to customers throughout Central Texas. Whether you need an emergency repair, a new roof, chimney repair or insulation installed in your attic, our crews have the skills and experience to provide quality work at reasonable prices. Submit our online form to request a free estimate, or call us at 512.777.1086.