We use a proprietary cleaning mixture that is applied to your roof with a diaphragm pump not a pressure washer.
Soft roof cleaning.
Verify your downspouts are connected to a gutter below.
So to get in front of the question of a pressure washer the term soft wash roof cleaning became one of several roof cleaning buzzwords.
So to answer your question.
Inspect your exterior walls for leaks and staining.
The main culprit of most roof staining that causes prevalent black streaks is a bacteria called gloeocapsa magma.
In order to clean your roof safely and effectively we use a soft wash cleaning system which exerts no pressure on your roof.
Soft washing is more than roof cleaning.
It will not harm any landscaping around the home yet is 100 effective at removing roof stains from algae.
Algae growth staining and any other type of bacterial or fungal infestations are required to be cleaned or removed from the shingles in order to maintain their issued warranties.
Only soft wash your roof.
The non bleach green eco friendly low pressure roof shampoo roof cleaning method uses a proprietary soap that is specially formulated and buffered to be safe on all asphalt and fiberglass shingles.
All these terms mean is a sensible use of pressure to rinse the roof without damaging the shingles or roof tiles.
Soft wash roof cleaning roof cleaning should never be done with a pressure washer.
The products developed for softwash systems not only clean stains but also sanitize penetrate and eliminate the root of the issue.
High volume low pressure rinse roof shampoo and others.