How to Remove Black Streaks From Your Roof in Northeast Ohio

To remove black streaks from your roof, have it soft washed. A low-pressure cleaning solution kills the Gloeocapsa magma bacteria that causes the streaks and rinses it away, without the high pressure that strips granules off asphalt shingles.

What causes black streaks on roofs in Northeast Ohio?

The dark black or gray streaks running down so many roofs in Rocky River, Westlake and Bay Village are a living organism. It is a bacteria called Gloeocapsa magma, and it thrives in humid climates like ours.

It feeds on the limestone filler in asphalt shingles, the material that helps hold them together. Left alone, it wears down the shingles, shortens the life of the roof and makes the whole house look older than it is.

Many people assume the streaks are dirt or mold and try to scrub or hose them off. That rarely works, because the bacteria keeps growing as long as it has shingle to feed on.

Why are west side roofs so prone to streaking?

Cleveland's west side has a lot working in the bacteria's favor. Lake Erie and the Rocky River valley keep the air humid, and heavy tree cover keeps many roofs in shade for much of the day.

That is why the north-facing and shaded sections of a roof are usually the first to streak. If you see it starting there, the rest of the roof tends to follow.

Can you pressure wash black streaks off a roof?

We do not recommend it. High-pressure water strips away the protective granules on asphalt shingles, and that damage can shorten the life of the roof.

DIY pressure washing also tends to blast the surface without killing the bacteria underneath, so the streaks come back. A ladder and a pressure wand on a sloped roof is also a real fall risk for a homeowner.

If you are not sure what is on your roof, look for dark streaks starting at the top edge and running down toward the gutters, often heaviest on the shaded side. Green or fuzzy patches are usually algae or moss, and soft washing treats those too.

How does roof soft washing remove black streaks?

Soft washing applies a cleaning solution at low pressure. The solution kills Gloeocapsa magma at the root, and a gentle rinse carries it away without disturbing the shingles.

Because the bacteria is killed at the root, results from soft washing last much longer than anything a pressure washer can do. The streaks disappear after treatment, and the shingles keep their granules. Here is what our crews do on every roof:

• Soak the landscaping before any solution goes on
• Apply the cleaning solution at low pressure across the streaked areas
• Treat algae, moss and mildew along with the black streaks
• Rinse the roof and the plants below when the job is done

When should you book roof cleaning?

Sooner is better. The longer the bacteria sits on your roof, the more of the shingle it eats and the more it drags down your curb appeal.

We soft wash roofs across Rocky River, Westlake, Bay Village, Avon Lake, North Olmsted, Fairview Park, Lakewood and the rest of Cleveland's west side. Our crews handle the work from start to finish, and you pay after the job with no deposit. If you are also due for a house wash or window cleaning, bundling services on one visit saves you money.

Book a free in-person quote online or text (440) 865-8993, and we will look at the property, give you an exact price, and often do the work on the same visit.

Next steps

• Roof Washing