Roof cleaning of asphalt shingle roofs is a somewhat new trade of pressure washing companies. The process can be pretty simple if you know how roofs are installed, any problems to avoid and what kind of stains need to be cleaned off. Pressure washing companies know that there is a good amount of technique and skill required when cleaning roofs properly. Make sure that your contractor who performs your roof cleaning is aware of how roofs are installed.
If they fail to fully understand methods of roof installations can possibly cost you thousands of dollars in roofing damage. Your pressure washing contractor should only use extremely low pressure in order to avoid damaging the shingles. The roof should also be inspected prior to the job to make sure there are no weak spots or loose shingles. Most of the pressure wash machines that are used in roof cleaning will use a minimum of 4 GPM and as high as 10 GPM!. So that is why it is crucial to understand the knowledge of roofing installation and make sure a proper roof inspection is done to ensure that water will not enter the structure during roof cleaning.