The black streaks on a roof in Ohio are primarily a problem in terms of curb appeal. The moss is the costly issue. The point is important when hiring a roof cleaning service because many companies offer to deal with the stains first but consider moss a secondary issue. The Asphalt Roofing Manufacturers Association mentions that there’s no scientific evidence stating that black algae are harmful to roofing.
Moss, on the contrary, creates problems. It curls and lifts up the edges of the shingles, thus increasing the chances of them blowing off during a storm while also pushing water under the shingles instead of downwards. Thus, cosmetic issues with the roofing may lead to serious problems with the roof.
This is why picking a roof cleaning service based on price alone is not a good choice. The non-pressure roof cleaning that we offer in Stark County is based on a careful examination of the roof.
Know What is Actually Growing Up There
Three things grow on Northeast Ohio shingles, and they do not carry the same weight.
- Algae (Gloeocapsa magma). The dark streaks. A blue-green cyanobacteria that produces a pigmented sheath to shield itself from UV, which is why it reads black from the driveway. By the time you see it, it has been up there for months.
- Moss. Grows on north-facing planes that stay damp longer and under overhanging branches. This is the growth that costs money if you ignore it.
- Lichen. Attaches harder than moss and marks the granule surface even after it dies.
Algae spores travel on wind and animals, which is why streaking marches down a whole street. A neighbor’s untreated roof will reseed yours.
Any roof cleaning professionals worth hiring will name what is on your roof during the estimate instead of quoting a flat “roof wash.”
Any Roof Cleaning Company That Reaches for a Pressure Washer Should Be Sent Home
ARMA’s guidance is blunt: never use a pressure washer on an asphalt shingle roof, because it strips granules and very likely causes premature failure of the roof system. Those granules are the shingle’s UV shield, and once they are in your gutters, they are not going back.
The method manufacturers actually endorse is chemical. A 50:50 mix of laundry-strength chlorine bleach and water goes on with a sprayer, dwells 15 to 20 minutes without drying out, and gets rinsed with low-pressure water. That is soft washing. It kills the organism instead of scraping the surface it sits on.
Pressure washing is the right tool for concrete and hard surfaces, and it has no business on shingles. If a contractor says their pressure is “adjusted low enough” for a roof, ask what PSI they run and watch how fast the answer gets vague.
What to Look for in a Roof Cleaning Service Before You Sign
Ohio issues no state license for professional roof cleaning, so nobody is vetting these companies for you. That job is yours, and it takes about ten minutes.
- A certificate of insurance sent by the insurer, not forwarded by the contractor. General liability and Ohio workers’ compensation both. A PDF from the company’s own inbox proves nothing about whether the policy is still active.
- Workers’ comp specifically. Ohio requires it of any employer with one or more employees. If an uninsured crew member falls off your roof, that claim can land on your homeowners policy.
- Pricing by measured square footage. Established roof cleaning companies measure the roof surface rather than guessing from the curb.
- A written warranty on the result. Ask how long the streaks are guaranteed to stay gone and what triggers a free re-treatment.
- A plant protection protocol. ARMA’s instructions call for protecting landscaping from the bleach solution. Ask whether they pre-wet and rinse the beds or just “work carefully.”
- Ladder and height training. Annual safety and technique training separates a maintenance company from someone who bought a machine in March.
Reviews help, but read the three-star ones. That is where you learn how a company handles a callback.
How to Prepare for Professional Roof Cleaning
Good crews handle most of this, and the visit goes faster when you have done your part.
- Close every window and door on the wash side, basement hoppers included.
- Move vehicles, grills, and patio furniture out from under the roofline.
- Keep pets inside during the work and for an hour after the final rinse.
- Flag what the crew cannot see from the ground: skylights, solar panels, a soft spot in the decking.
- Book gutter cleaning in the same window. Runoff carries loosened moss and granules into the troughs, and ARMA lists clean gutters as part of preventing regrowth.
Hire the Company That Names the Problem First
The roof cleaning company to hire is the one that tells you the moss on the north slope is the real issue and the streaks on the south face are cosmetic. That answer is less dramatic than a replacement quote, and it is the honest one. A roof treated on a schedule holds its granules longer, and treatment costs a fraction of a tear-off.
If your roof is streaking or holding moss, get a measured quote from professional roof cleaners who will put the method, the insurance, and the warranty in writing. Request a fast quote from Exact Prowash or call (330) 639-5249), and we will tell you what is growing before we tell you a price.
Frequently Asked Questions
▶ How much does professional roof cleaning cost?
Reputable roof cleaning companies typically charge based on square footage, meaning price relies on roof size, pitch, and how much moss is involved in the cleaning rather than being washed away. Steep or multilevel roofs require extra money for safety and access work.
▶ How often should an Ohio roof be cleaned?
Most homes in Northeast and Central Ohio will need roof cleaning only once a year. Homes facing the north and covered by trees need more cleaning than others.
▶ Will roof cleaning void my shingle warranty?
Soft washing must be done according to manufacturer guidelines. Pressure washing should not be done, as this can lead to granule loss. Therefore, the Asphalt Roofing Manufacturers Association warns homeowners against using pressure water on asphalt shingles.
▶ Should I add zinc or copper strips instead?
There is no point doing it on an already installed roof, according to the Asphalt Roofing Manufacturers Association, as while installing strips a homeowner is exposing nails, which will eventually lead to leaking, or a homeowner is breaking the shingle sealant and having to fit strips under it.
