Roof Cleaning Ottawa: How Soft Washing Removes Black Streaks & Moss
Those black streaks on your roof are algae, not dirt. Learn how professional soft washing removes them safely and extends your shingles' lifespan.
If you've noticed dark streaks running down your asphalt shingles, that's not just dirt—it's gloeocapsa magma, a algae that feeds on the limestone filler in shingles. Left untreated, it spreads and can shorten your roof's lifespan by years.
Why You Should Never Pressure Wash a Roof
High-pressure water blasted directly at asphalt shingles strips away the protective granules that shield them from UV damage. Once granules are gone, they don't grow back—you've effectively aged your roof by years in a single afternoon. This is why every reputable roofing manufacturer recommends soft washing, not pressure washing, for roof cleaning.
How Roof Soft Washing Works
We apply a biodegradable, low-pressure cleaning solution from the ground or roof edge using specialized equipment. The solution breaks down algae, moss, and lichen at the root, and rinses away gently—no scrubbing, no high-pressure spray, no granule loss.
- Black Streak Removal: Algae stains lift away, restoring your roof's original color.
- Moss & Lichen Treatment: Our solution kills moss at the root so it doesn't grow back as quickly as a manual scrape would allow.
- Gutter Protection: We rinse debris away from gutter openings as part of the process.
- Curb Appeal: A clean roof is one of the fastest ways to improve how your whole home looks from the street.
Signs Your Roof Needs Cleaning
- Dark streaks running vertically down the shingles
- Green or black patches in shaded areas, especially north-facing slopes
- Moss growing along the roofline or in valleys
- Visible granule buildup in gutters or downspouts
Pricing & Service Areas
Roof soft washing starts at $450 depending on roof size and pitch. We serve Ottawa, Kanata, Orleans, Barrhaven, Nepean, and surrounding areas. Bundle with gutter cleaning for the best results and a multi-service discount.
Frequently Asked Questions
Is roof soft washing safe for my plants and landscaping?
Yes, our solutions are biodegradable and we take care to pre-rinse and protect surrounding plants and grass during application.
How long do roof soft wash results last?
Most homes stay streak-free for 2-4 years, much longer than the algae regrowth you'd see after a manual scrub or pressure wash.
Does soft washing work on metal or cedar roofs?
Yes, soft washing is gentle enough for metal, cedar shake, and tile roofs in addition to standard asphalt shingles.
Want the full picture on safe cleaning methods? Read our soft wash vs. pressure wash guide or check out our gutter cleaning guide to protect your whole roofline.
Restore Your Roof's Curb Appeal
Remove black streaks and moss safely—without risking your shingles.
Get a Roof Cleaning Quote