Moss Removal: Why Hand-Brushing Beats Pressure Washing Every Time

If you live anywhere between Olympia and Tacoma, moss is not a question of if — it's a question of how much. Our climate gives moss everything it wants: shade, moisture, and mild temperatures nine months out of the year. Left alone, it does real structural damage.

Here's the mechanism. Moss doesn't just sit on top of your shingles. It grows underneath the edges and lifts them, breaking the seal that keeps wind-driven rain out. It also holds water against the shingle surface long after the rain stops, which accelerates granule loss and eventually rots the decking underneath. By the time you see a stain on the ceiling, the deck has usually been wet for a long time.

So why not just pressure wash it off? Because the granules on an asphalt shingle are the shingle's sunscreen and armor — and they are only held on by the asphalt layer beneath them. A pressure washer blasts them off in sheets. A roof that gets pressure washed often looks great for a month and then ages five years in one season. Worse, high pressure drives water up under the shingle courses, which is exactly where you don't want it.

The professional method is slower and it works: hand-brushing. We work down the roof course by course with brushes, lifting moss off the surface without scouring the granules. It takes a crew most of a day on an average home. We follow it with a roof-safe moss treatment that kills the remaining spores so regrowth is slow instead of immediate, then clear the valleys, gutters, and downspouts so water actually leaves the roof.

How often should it be done? For most homes in Thurston and Pierce County, every two to three years — more often if you're under heavy tree cover in Shelton, Lakewood, or Tumwater Hill.

VZR Roof Services cleans roofs by hand across Olympia, Lacey, Tumwater, Tacoma, and the surrounding cities, and roof cleanings are currently 10% off. Call (360) 884-2185 for a free roof inspection.