Mr. GoodRoof | Nashville & Middle Tennessee
Black Streaks on Your Roof? Here's What to Do Next.
A cleaner roof starts with knowing what you are cleaning — and what needs attention first.
Looking for cleaning only? Request a SoftWash estimate.
Reviewed by the Mr. GoodRoof roofing team · Updated September 16, 2026
You notice the streaks. We look at the roof.
Dark streaks can make the whole house look tired. It is reasonable to want them gone. But choosing who cleans the roof should involve more than comparing the before-and-after picture.
We are a roofing company. Before we clean or treat shingles, we look at their condition and the roof system around them. That is how we separate a cleaning concern from repairs, drainage issues, or other conditions that deserve attention.
For Nashville and Middle Tennessee homeowners, Mr. GoodRoof offers standalone Professional Roof SoftWash and the complete GoodShield Roof Restoration System. We start by explaining what your roof actually needs.
Quick answer
What causes black streaks on asphalt shingles?
Black or brown streaks on asphalt-shingle roofs are commonly associated with algae discoloration. Streaks alone do not tell you whether the roof is failing — or whether it is in good condition. We evaluate the staining and the shingles separately, then recommend cleaning, corrective work, the complete GoodShield system for a qualifying roof, or another appropriate path. [1]
On this page
- What causes black streaks on asphalt shingles?
- Black streaks, moss, and worn shingles are not the same thing
- Why black streaks are so common in Middle Tennessee
- Why we evaluate the roof before washing it
- Yes, you can hire us for roof cleaning only
- Cleaning is only the first step in GoodShield
- The five-stage GoodShield process
- What should you expect to see afterward?
- Before-and-after project photos
- Video: black streaks on roofs
- What about the patch that already stands out?
- Compare the scope — not just the phrase "roof wash"
- Start with a clear answer about your roof
- Frequently asked questions
Black Streaks, Moss, and Worn Shingles Are Not the Same Thing
Flat dark staining is different from raised growth or a surface that has lost its granules. Algae discoloration is often what a homeowner is describing when they call about black streaks. Moss, lichen, debris, and physical shingle deterioration need their own assessment. [1][2]
We do not label every dark area "mold," and we do not assume that every stained roof needs the same service. Photos help us understand the concern, but they do not replace checking the actual roof.
Seeing grit in the gutters or bare-looking areas as well? Start with our guide to shingles losing granules. That is a different condition question from stain removal.
Why Black Streaks Are So Common in Middle Tennessee
Algae discoloration shows up across the country, but it tends to be most widespread where the weather is warm and humid — a good description of a typical Middle Tennessee summer. The algae travel through the air, so it is common to see streaking on several homes in the same neighborhood. The staining is also easier to spot on lighter-colored shingles than on darker ones. [1]
Streaking is not always even across a roof, which is one reason we look at every slope instead of judging from a single photo.
Why We Evaluate the Roof Before Washing It
A clean surface is not the same thing as a sound roof. We check the visible shingle condition, repair areas, penetrations, drainage, and the broader roof conditions relevant to the work. Where attic or ventilation concerns need further attention, we explain those findings rather than guessing from a streak on the outside.
We look for the difference between something cleaning can address and something that needs roof repair. Loose or missing materials and an active leak require a repair conversation. Cleaning is not the repair.
Our ventilation services are another part of that roofing expertise. Ventilation may be relevant to a roof's aging or moisture concerns; black streaks alone are not a ventilation diagnosis.
That is what we mean by roofing expertise is built in. We can discuss the surface and what needs attention beyond it.
Yes, You Can Hire Us for Roof Cleaning Only
Mr. GoodRoof Professional Roof SoftWash is a standalone service for homeowners who want professional cleaning without rejuvenation. We confirm the scope, assess the roof, and explain the cleaning approach and expected appearance.
Professional softwashing uses a low-pressure approach appropriate to the roof and applicable manufacturer guidance. Aggressive pressure washing or scrubbing is not the approach we recommend for asphalt shingles. Different roofing materials and conditions can require different instructions, so we check before proceeding. [1]
We also discuss the work around the roof, including access and property-protection procedures. A responsible cleaning plan accounts for more than the shingles alone.
Cleaning Is Only the First Step in GoodShield
When the roof qualifies for GoodShield, professional cleaning is part of the complete system — not the entire service.
The GoodShield Roof Restoration System is Professional Roof Cleaning + Asphalt-Shingle Rejuvenation, delivered by Mr. GoodRoof. We evaluate the roof, identify corrective work, clean it, apply the GoodShield rejuvenation treatment to the prepared roof, and document the work and maintenance guidance.
Cleaning and rejuvenation are separate steps with different purposes. Removing discoloration does not, by itself, establish that the shingles' physical properties have changed. That is why we describe the actual work performed instead of calling every clean roof "rejuvenated."
For a roof accepted as a GoodShield candidate, our recommendation is the complete system. Standalone SoftWash remains available for cleaning-specific needs and requests. Any necessary repairs or ventilation corrections are separately identified in the scope.
The Five-Stage GoodShield Process
- EvaluateAssess the shingles, staining, repair needs, drainage, ventilation considerations, and treatment eligibility.
- CorrectComplete or separately scope the approved repairs and other necessary corrections before treatment.
- CleanProfessionally softwash the roof with the appropriate low-pressure process.
- RejuvenateApply the GoodShield rejuvenation treatment to the qualified, prepared asphalt shingles.
- Document & MaintainProvide project documentation and the applicable maintenance guidance.
What Should You Expect to See Afterward?
We discuss the visible result in relation to the actual condition. Algae discoloration, raised growth, old repair patches, and worn shingle surfaces are not interchangeable concerns. Not every mark is something a wash can remove.
For project photographs, the useful comparison is the same roof area from a similar angle after the surface has dried. A dramatic-looking wet surface is not a substitute for documenting the finished work.
Cleaning also does not make a roof immune to future discoloration. Conditions that support algae can continue after a cleaning, so we discuss maintenance rather than promise that streaks will never return. [1]
Before and After: GoodShield Projects Around Middle Tennessee
Real roofs from GoodShield projects. Each pair shows the same home before and after the work.
Before and after photos were taken at different times of day and from slightly different positions. Sunlight and cloud cover change how a roof's color looks in a photo, so the most reliable comparison is always an in-person look at your own roof.
Watch: Black Streaks on a Roof
What About the Patch That Already Stands Out?
A homeowner may call about black streaks and also point out a brighter area where shingles were replaced. That deserves a separate look. The difference may involve the replacement material, the existing roof's weathering, discoloration, or a combination.
Our shingle-matching and repair-appearance guide explains how we consider the repair and the surrounding roof together — and where GoodShield fits after qualifying repair work.
Compare the Scope — Not Just the Phrase "Roof Wash"
Ask who evaluates the roof, how repairs are handled, what cleaning method is planned, and whether the quote is cleaning only or a complete cleaning-and-rejuvenation project. Those are different services.
Our roof-cleaning cost guide explains the factors to discuss when requesting an estimate. The final scope should reflect your roof, not just your home's interior square footage or a generic online number.
Still deciding which direction makes sense? Read our roof-care decision guide or have us evaluate the roof.
"Mr. GoodRoof went the extra mile to clean and treat a difficult north facing roof slope... Cory explained in detail what he was doing and how the process would assist in the cleaning. They cleaned up after the job, showed us before and after pictures of the work."
— Cindy Purviance
Start With a Clear Answer About Your Roof.
You do not need to know the name of a treatment before calling us. Tell us what you are seeing and what you want to address. We will explain the condition, the appropriate service, and the work included.
Black Streaks Questions
Do black streaks mean I need a new roof?
No — not by themselves. Streaks can be algae discoloration, while the roof's repairability and overall condition are separate questions. We evaluate the roof before recommending cleaning, repair, GoodShield, or replacement.
Are the black streaks always mold?
No. Algae discoloration is a common cause of black or brown streaking on asphalt shingles. We assess the actual condition instead of calling every dark area mold.
Can you pressure-wash my shingles?
We use an appropriate low-pressure roof-cleaning approach, not aggressive pressure washing. The roofing material, condition, and applicable manufacturer instructions guide the work.
Does GoodShield include cleaning?
Yes. Professional roof softwashing is included in the complete GoodShield Roof Restoration System, followed by rejuvenation treatment on a qualifying, prepared asphalt-shingle roof.
Can I request just the cleaning?
Yes. Mr. GoodRoof Professional Roof SoftWash is available separately. A cleaning-only request does not require buying GoodShield.
Does cleaning fix leaks or missing shingles?
No. Those are repair conditions. We identify and scope the appropriate corrective work separately from cleaning and treatment.
Will the streaks ever return?
They can. Cleaning addresses the current discoloration; it is not a promise against all future algae growth. We explain maintenance and the conditions relevant to your roof.
Can I clean black streaks off my roof myself?
The Asphalt Roofing Manufacturers Association (ARMA) notes that algae discoloration can be lightened with a diluted household-bleach solution, but it also warns that the process makes a roof slippery and recommends that only trained professionals work on roofs. ARMA advises against pressure washers, brushes, and scrubbing, which can loosen granules. If you would rather stay off the roof, we can clean it for you and check its condition while we are up there. [1]
How much does it cost to remove black streaks?
Professional roof cleaning typically starts around $1 per square foot, depending on roof size, pitch, access, and condition. The complete GoodShield system is a different scope and is priced differently, and we explain what each option includes before you decide. See our roof-cleaning cost guide for what affects the price.
Is there a warranty?
Qualifying GoodShield rejuvenation projects may include a five-year, prorated, transferable warranty, subject to its written terms. Cleaning-only service is a separate scope.
Tell Us What You're Noticing
Schedule a GoodShield Roof Evaluation. Our team will help you take the next step.
Sources and Further Reading
These sources support the general roofing explanations, not GoodShield-specific product performance.
