Roof Soft Washing in Richmond, VA

The dark streaking on asphalt shingle roofs is a blue-green algae that feeds on the limestone filler in the shingles. It spreads by airborne spores, which is why it tends to show up on a whole street at once, and it thrives on the shaded, north-facing slopes that stay damp longest.

Left alone it holds moisture against the roof and gives moss and lichen somewhere to take hold. Moss lifts shingle edges and lichen roots into the granules, and both shorten the life of the roof.

High pressure strips the protective granules off asphalt shingles, which is the part that shields them from UV. It can also lift shingles, break seals and force water underneath. Shingle manufacturers recommend low-pressure chemical cleaning for exactly this reason.

Soft washing applies a solution that kills the algae, moss and lichen where it grows. The streaks fade as it works, heavier growth releases over the following weeks with rainfall, and nothing abrasive touches the shingles.

Black streaking clears quickly. Thick moss and lichen die off and then weather away over several weeks rather than being scraped, because scraping takes granules with it. Because the growth is killed rather than rinsed, results typically last for years rather than months.