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Yes. Pressure washing will dislodge the granules from the surface of the shingles and can scar the shingles causing more problems than you started with. Shingle manufacturers make it very clear that no pressure should be used to clean roofs. Although leaving the roof apparently clean looking, pressure washing alone does not kill the algae and the problem quickly returns. Tile roofs are also susceptible to damage from pressure, particularly the glaze finish and color pigment. The typical result is that the tile loses its color and is left far more porous. The new porous surface fosters the regrowth of algae, lichen, and moss. Removing the outer surface of roof tile using pressure also allows moisture to enter the tile which accelerates degradation.