Those black streaks on your asphalt shingle roof are usually blue-green algae, commonly called Gloeocapsa magma. The streaks are mainly an appearance problem: the Asphalt Roofing Manufacturers Association says there is no scientific evidence that algae damages asphalt shingles, but moss, leaks, and worn-out shingles are separate concerns. [1, 2]

That means a streaky roof does not automatically need replacing. It also means you deserve a better explanation than “your roof is being eaten” before paying someone to clean it.

What causes black streaks on roofs in DFW

The algae produces a dark protective coating, which is what you see from the driveway. It needs moisture to grow, and morning dew can supply it. North-facing slopes and shaded sections often stay damp longer, so one side of your roof may look worse than the other. [2]

Texas heat does not mean every part of your roof stays dry. Think about a shaded roof in Colleyville, Keller, or Southlake after a humid night or spring rain. Trees can keep sunlight off the shingles long after the rest of the house has dried.

Oak pollen and fallen leaves are other cleanup concerns, but their presence does not explain every black streak. The same goes for hard-water marks elsewhere on your exterior. Identify the stain before choosing a treatment.

Does roof algae damage asphalt shingles

Ordinary algae staining is mainly cosmetic. Flat, dark streaks and thick, raised growth are different problems. Moss can hold moisture and lift shingle edges, making the roof more vulnerable to wind and water intrusion. Algae can also reduce the effectiveness of highly reflective “cool” roofs. [1]

• Have a roofer check the roof before cleaning if you notice:
• Missing, cracked, or curling shingles.
• Bare-looking patches or obvious shingle deterioration.
• Ceiling stains, active leaks, or sagging areas.
• Suspected damage after a North Texas hailstorm.

Cleaning cannot fix damaged shingles, flashing, or roof decking. If the roof needs repairs or replacement, put your money toward that first. A clean roof can still leak. [3]

How to remove black streaks from roof shingles

For a suitable asphalt shingle roof, soft washing uses a cleaning solution applied at low pressure to treat the growth. The method and solution should follow your shingle manufacturer’s instructions.

Do not let someone blast the shingles with a pressure washer or scrub them with a stiff brush. Those methods can remove protective granules. ARMA specifically warns against pressure washing and brushing asphalt shingles. [4]

The term “softwash” alone does not tell you whether a contractor is doing the job correctly. Ask what they will apply, how they will rinse, and how they will protect the landscaping and surrounding surfaces. Learn more about our roof soft washing service in Colleyville.

How much does roof soft washing cost

For a published starting point, Angi’s 2026 cost guide lists about $560–$900 for soft washing a 1,600-square-foot roof, including labor and materials. That is a national benchmark, not a Sparkles SoftWash quote or a guaranteed DFW price. [5]

Your price depends on the actual roof area, pitch, height, access, amount of growth, and time needed to protect the property. A large, steep roof with several sections takes more work than a small roof with easy access.

Roof area is also different from the living space listed on your home’s floor plan. Ask whether the estimate includes the whole roof, debris removal, gutter cleaning, and any follow-up treatment. A lower number is only useful when you know what it covers.

What are the risks and limitations of roof cleaning

Soft washing is not risk-free. Cleaning chemicals can harm landscaping and surrounding surfaces if handled poorly. Wet roofs become slippery, and walking on them adds risk. A contractor should explain the protection and access plan before starting. [4]

Cleaning also has limits:

• It cannot replace missing granules or repair storm damage.
• It cannot make an old roof new again.
• It is not a permanent cure. Algae discoloration can return. [3, 4]

Be cautious of promises that one cleaning will add a specific number of years to your roof or guarantee lower electric bills. A dramatic before-and-after picture does not prove either claim.

When cleaning is worth it and when you can wait

Cleaning may make sense when the shingles are in serviceable condition and you want the stains removed, are preparing to sell, or need to address an HOA appearance notice.

If your HOA has contacted you, ask exactly what needs correcting and what deadline applies. An appearance notice does not establish that the roof is damaged.

If you have only algae staining, the roof is otherwise sound, and the appearance does not bother you, immediate cleaning may not be necessary. If replacement is already planned, paying for a cosmetic cleaning may offer little value.

To discourage regrowth, have overhanging branches trimmed appropriately, keep gutters draining, and arrange for accumulated roof debris to be removed safely. These steps help manage moisture and shade; they do not guarantee a streak-free roof forever. If leaves are blocking drainage, our gutter cleaning service can help address that separate issue. [1]

Roof cleaning in Colleyville and the surrounding DFW area

Start with photos taken from the ground. Note whether you see flat streaks, raised growth, missing shingles, or signs of a leak.

Sparkles SoftWash serves Colleyville, Keller, Southlake, Fort Worth, and surrounding communities. Request a roof-cleaning quote or call (817) 813-3318. Mention any known leaks, recent hail damage, or HOA deadline so those concerns can be addressed before work is scheduled. [6]