Roof cleaning is probably the most misunderstood service we offer. A lot of homeowners see dark streaks or green patches on their roof and figure it’s just aging. It’s usually not — it’s alive.
The black or dark gray streaks you see on roofs around Vancouver are almost always Gloeocapsa Magma, a type of algae that feeds on the limestone filler in asphalt shingles. The green patches are moss. Both hold moisture against the shingles and accelerate deterioration.
In Vancouver’s climate, roof growth is nearly universal on older homes. We see it constantly in Hazel Dell, Minnehaha, the Heights, and pretty much any established neighborhood with mature trees nearby. Shaded roofs get it faster, but even fully exposed roofs develop growth over time.
How We Clean Roofs:
We use soft washing for all roof cleaning. No pressure washing on shingles — ever. High pressure loosens granules, voids warranties, and can force water under shingles causing damage. Soft washing with the right solution kills the growth completely without damaging the shingles.
After treatment, the dead growth washes off naturally over the next few rainfalls. The roof looks progressively cleaner over the following weeks and stays clean significantly longer than pressure washing would achieve.
Common Questions About Pressure Washing in Vancouver, WA
What are the dark streaks on my roof?
Almost always algae — specifically Gloeocapsa Magma, which feeds on the limestone filler in asphalt shingles. It looks like dark gray or black streaking and is extremely common on Vancouver roofs, especially in neighborhoods with mature trees nearby. It’s not just cosmetic — it’s actively breaking down your shingles.
Is pressure washing safe for my roof?
No. High-pressure washing can strip granules from asphalt shingles, void manufacturer warranties, and shorten the life of your roof significantly. We use soft washing — low pressure combined with professional-grade cleaning solutions that kill algae, moss, and bacteria at the root without damaging the surface.
How long does roof cleaning last?
Soft washing treatments typically last 2–4 years depending on tree coverage, shade exposure, and rainfall. Because the solution kills growth at the source rather than just removing it physically, regrowth is significantly slower than after pressure washing.
How do I know if my roof needs cleaning?
Dark streaking, green or black patches, visible moss, or a roof that looks significantly darker than it used to are all signs of active growth. If your roof hasn’t been cleaned in 3 or more years and you’re in an established Vancouver neighborhood, it’s worth having it looked at.
Will roof cleaning damage my landscaping or gutters?
We take precautions to protect surrounding plants and landscaping during the cleaning process. Our cleaning solutions are applied carefully and rinsed properly to minimize runoff impact.
Don't Let Algae and Moss Cost You a Roof Replacement
If you’re seeing dark streaks, green patches, or a roof that just doesn’t look right, it’s worth getting it checked before the damage compounds.
Call us today for a free roof cleaning estimate. Or fill out the contact form and we’ll get back to you within one business day.