How Often Does a Roof Need to Be Cleaned?

1. The General Rule: Every Few Years

For the average home in a moderate climate, a professional soft wash treatment will keep the roof free of visible black streaks for several years. The specialized sodium hypochlorite solution used by professionals kills the algae down to the root, resetting the clock.

It takes several years for new airborne spores to land, attach, and multiply enough to become visible from the ground again.

2. Signs You Are Years Overdue For Cleaning (It's Not Too Late)

Do not wait until the roof is completely black to call a professional. You should schedule a cleaning as soon as the first distinct vertical streaks appear.

• The black streaks have merged into large, solid dark patches.
• You can see green, fuzzy moss growing near the edges of the shingles.
• Light green or white crusty lichen patches have appeared.
• There is a heavy accumulation of shingle granules at the bottom of your downspouts.