Last updated June 28, 2026
Roof Cleaning Guide for Homeowners
How roof soft washing safely clears black streaks and moss from your shingles without the damage pressure washing causes.
Roof soft washing removes black streaks, moss, and algae from shingles using low-pressure application and a roof-safe cleaning solution, the same low-pressure approach used on siding. Pressure washing a roof can lift or damage shingles, which is why soft washing is the recommended method for asphalt shingle roofs.
What Causes Black Streaks on a Roof?
Those dark streaks are usually a type of algae called Gloeocapsa magma, which feeds on the limestone filler in asphalt shingles. It spreads gradually across the roof, typically starting on the north-facing or shaded side where moisture lingers longest.
How roof soft washing works:
Inspect
The roof is checked for moss, algae, and any areas needing extra attention.
Protect
Surrounding landscaping and hardscape are protected before anything is applied.
Apply
A roof-safe cleaning solution is applied evenly at low pressure.
Let it work
The solution stays on the shingles and keeps killing the growth all the way down. There is no final rinse.
Because soft washing relies on the cleaning solution rather than water force, it doesn't dislodge or damage shingle granules the way pressure washing can.
Why There Is No Final Rinse
Algae, moss, and lichen root into the shingle surface, so the goal is never to blast them off. The solution kills the growth all the way down, the dead material loosens and lets go on its own, and normal rain and wind carry it away over the following weeks. Anything forceful enough to strip that growth off in a single pass is forceful enough to take shingle granules with it.
What to expect: Black streaks usually lighten quickly. Heavy moss and lichen take longer, often several weeks of normal weather, and you may notice pieces letting go after a rain. That is the process working, not a job left unfinished. If after a month there is still visible moss or lichen, we will come back to re-treat those areas, free of charge, no questions asked.
Removes
- Black algae streaking
- Moss buildup in shade
- Dirt and debris
- Lichen in some cases
Why Soft Wash, Not Pressure
- Pressure strips shingle granules
- Soft wash protects shingle life
- Kills growth at the root
- Results last 2 to 3 years
Is Roof Cleaning Worth It?
Beyond appearance, removing algae and moss helps prevent the kind of moisture retention that can shorten shingle lifespan over time. A clean roof also tends to reflect heat more effectively than one covered in dark algae streaking. For more on the streaking specifically, see our guide on how to remove black streaks from a roof.
Why Hire a Professional
Osborne Pro Wash is owner-operated and based in Morrow, Ohio, serving Morrow, Maineville, Mason, Loveland, Lebanon, Kings Mills, Landen, and South Lebanon. Spray Wash Academy certified soft wash technique, safe for asphalt shingles, fully insured, with a satisfaction guarantee. See our roof soft washing service, or request a free quote below.
Roof Cleaning FAQ
Will pressure washing damage my roof?
Yes, it can. High pressure can lift or strip shingle granules, which is why soft washing is the recommended method for roofs.
Can roof cleaning remove moss completely?
Yes, in most cases. Soft washing breaks down moss at the root, though heavily established moss may need a follow-up treatment.
Does roof cleaning shorten shingle life?
No, when done correctly with the soft wash method. It's pressure washing, not soft washing, that risks shortening shingle life.
How long do roof cleaning results last?
Most roofs stay clean for 2 to 3 years after a soft wash, depending on shade and moisture exposure.
Get Your Roof Looking Clean Again
Request a free, no-pressure quote for safe roof soft washing.