Moss Removal & Treatment

Moss grows thick on the area roofs, especially on north-facing slopes and under tree cover. Left alone, it lifts shingles and traps moisture, which rots the decking underneath. We remove it by hand-brushing the clumps off, then blowing the roof clean with backpack blowers. After the bulk is gone, we apply zinc sulfate powder. It kills the remaining moss and prevents regrowth for 1-2 years.

We do not pressure wash roofs. High pressure strips the protective granules off composition shingles and shortens the roof's life. The goal is to get the moss off and kill what's left while protecting the roof itself. If your roof is heavily covered, expect visible improvement immediately and full die-off over the next few weeks as the treatment works.

“We do not pressure wash roofs — high pressure strips the granules off composition shingles and shortens the roof's life.”

Green algae stains — the streaks that run down from the ridge — come off with the treatment too. Zinc sulfate breaks down the algae and prevents it from coming back. Most customers across King County schedule moss treatment every 2-3 years. If your roof is under heavy shade or you've got overhanging branches, you might need it more often.

We also clear debris — leaves, fir needles, branches — while we're up there. A clean roof sheds water better and lasts longer. Typical service takes 2-4 hours depending on roof size, pitch, and moss coverage. Steep roofs or complex layouts with multiple valleys and dormers take longer. We work safely with harnesses and proper footwear — no shortcuts.

For shake roofs, the process is similar but requires more care. Shakes are more fragile than composition shingles, so we use softer brushes and avoid aggressive scraping. The zinc sulfate treatment works the same way — kills the moss, prevents regrowth, and treats algae stains. If your shake roof hasn't been maintained in years, expect the first treatment to take longer as we remove years of buildup.