ABSOLUTLY NOT! High pressure powerwashing can be very damaging to the shingles. Here at Wall 2 Wall, we use a roof cleaning solution called “Roof Snot” that is mixed with Sodium Hypo-Chloride, soaps, and water. Its a thicker solution that helps stick to the roof top and gets left up on the roof for the sun to bake it into the shingles to get rid of the mold/algae.