ROOF CARE
How Often Should You Clean Your Roof in the Pacific Northwest?
By Kole · Peterson Property Services · 3 min read
If you live around Snohomish or King County, you have seen it, that green-black moss creeping across shingles by the second winter. Our cool, damp, tree-shaded climate is about the friendliest place in the country for roof moss. The good news: staying ahead of it is simple and cheap compared to a new roof.
Why PNW roofs grow moss so fast
Moss needs moisture and shade, and we have both in spades. Overhanging trees drop debris that holds water against the shingles, and north-facing slopes rarely dry out. Left alone, moss lifts and curls the shingle edges, traps water, and shortens the life of the roof.
So how often should you clean it?
For most homes here, a roof treatment every 1 to 2 years keeps moss from ever getting a foothold. If you have heavy tree cover or a lot of shade, closer to once a year is smart. If it has already been several years, start with a full treatment and then settle into a maintenance rhythm.
Heavy shade or tree cover: about once a year
Average exposure: every 1 to 2 years
Already mossy: treat now, then maintain
Why I never pressure wash a roof
This is the big one. Pressure washing strips the protective granules off asphalt shingles, voids many manufacturer warranties, and can force water under the shingles. I clean roofs with a soft brush and a moss-killing powder treatment instead, no high pressure. The treatment keeps working after I leave to slow regrowth, and your shingles stay intact.
The bottom line
A little maintenance beats a big repair. If you are not sure where your roof stands, I am happy to take a look and tell you honestly whether it needs treatment yet, no pressure, and $50 off your first service.
Ready to see your property shine?
Get your free quote today and take $50 off your first service.