Everything you need to understand what's growing on your roof, whether it's actually a problem, and the safest way to deal with it.
Click the symptom that best describes what you're seeing. We'll point you to the right guide.
Long dark lines running down the roof
Thick green or brown patches, especially on north side
Hard, crusty patches that won't brush off
Reddish-brown streaks or patches on metal or tile
Thin green coating, slippery when wet
Irregular dark areas, not streaks
Those dark lines running down your shingles aren't dirt, and they're not your roof aging. They're a living organism called Gloeocapsa Magma — a cyanobacteria that feeds on the crushed limestone in your shingles. Ohio's humid summers are ideal for it to spread.
The bad news: it's actively degrading your roof. The good news: it's completely treatable without replacing a single shingle.
Read the full guide →In-depth guides written for Columbus homeowners — no jargon, no upsells.
Learn what this cyanobacteria actually is, why it thrives in Ohio, how fast it spreads, and what it's doing to your shingles right now.
Read Guide →Moss looks harmless, but its root-like rhizoids physically lift shingles and trap moisture against the deck. Here's how to assess the damage and what to do about it.
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Lichen is a symbiotic organism — part algae, part fungus — that bonds directly to roofing material with a cement-like grip. Pressure washing makes it worse. Here's the right approach.
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Pressure washing a roof feels satisfying — but it will remove the granules that protect your shingles and void your warranty. Here's why the way we gently clean a roof is the only way to clean it without damage.
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Not all orange stains on metal roofs are rust. Learn how to tell the difference between surface oxidation, algae staining, and actual corrosion — and what each one means for your roof's lifespan.
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Cedar is a natural, porous wood that breathes. Pressure washing, bleach, and improper cleaners strip the natural oils and split the shakes. Here's the only safe way to clean cedar.
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Both are green, both grow on roofs — but they're very different organisms with different risks and different treatments. Knowing which one you have changes how you approach the fix.
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Columbus's climate — humid summers, wet springs, and shaded lots — creates near-perfect conditions for bio-growth. Here's a practical maintenance schedule based on your roof type and tree coverage.
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We'll be straight with you: some homeowners can safely treat minor algae growth themselves. But there are real risks — to your roof, your warranty, and your safety. Here's how to decide.
Read Guide →In-depth, expert-written guides for homeowners, home sellers, buyers, realtors, and property managers. Free to read — no email required.
Everything you need to know about why roofs get dirty, how professional treatments work, and how to choose the right company. 3,100+ words of expert guidance.
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Month-by-month maintenance schedule tailored for Ohio's climate. Know exactly when to inspect, clean gutters, and schedule professional treatment.
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Shingle, cedar, slate, tile, metal, and flat roofs — learn how each type gets dirty, what damages it, and the correct cleaning approach for your specific roof.
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Identify algae, moss, lichen, mold, and other growths by sight. Includes risk levels, damage timelines, and recommended treatment for each organism.
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A room-by-room, surface-by-surface checklist for maximizing curb appeal before listing. Includes timeline, priority order, and ROI estimates for each task.
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Hard data on how roof cleaning, pressure washing, and curb appeal improvements affect appraisal values, days on market, and final sale price.
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What to look for during a home inspection, how to read a roof report, and when to negotiate repairs vs. walk away. Protect your investment before closing.
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Your first-year guide to maintaining your new home's exterior. Covers roof, gutters, siding, driveway, landscaping, and seasonal maintenance schedules.
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How top-producing agents use professional exterior cleaning to win listings, reduce days on market, and increase sale prices. Includes scripts and talking points.
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See real transformations on shingle, cedar, slate, and commercial roofs. Includes what to expect after treatment and the 60-90 day timeline for full results.
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Transparent pricing guide with cost ranges by roof type, size, and condition. Includes factors that affect price and how to compare quotes from different companies.
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Answer a few quick questions about what you see on your roof and get an instant diagnosis with recommended next steps and urgency level.
Take the Quiz →Use this table to identify what you're seeing and understand the risk level.
| What You See | What It Is | Risk Level | Safe Treatment | Urgency |
|---|---|---|---|---|
| Dark streaks running down shingles | Gloeocapsa Magma (cyanobacteria) | Medium–High | Treatment biocide solution | Within 1 season |
| Thick green/brown fuzzy patches | Moss | High | Treatment + post-treatment | Promptly — lifts shingles |
| Hard white/gray crusty patches | Lichen | High | Treatment (multi-application) | Promptly — bonds to material |
| Thin green film, slippery when wet | Green algae | Low–Medium | Treatment biocide solution | Within 1–2 seasons |
| Orange/rust streaks on metal | Oxidation or algae staining | Medium | Metal-safe treatment | Within 1 season |
| Black patches on cedar shakes | Algae + moisture damage | High | Cedar-safe treatment only | Promptly — wood damage |
| Dark discoloration on tile | Algae, mold, or lichen | Medium | Tile-safe treatment | Within 1–2 seasons |
| Granules in gutters | Shingle granule loss (not bio-growth) | High | Roof inspection — may need replacement | Inspect immediately |
Gloeocapsa Magma is a type of cyanobacteria — a photosynthetic microorganism — that has adapted to live on rooftops across the eastern United States. It's been around for decades, but it became dramatically more common in the 1970s when asphalt shingle manufacturers began adding crushed limestone as a filler to reduce costs. That limestone is Gloeocapsa Magma's food source.
The organism itself is actually blue-green. The dark, almost black color you see on roofs is a protective pigment — a dark sheath the bacteria produces to shield itself from UV radiation. It's essentially sunscreen. This is why the streaks get darker over time: the colony grows and produces more pigment.
Gloeocapsa Magma spreads via airborne spores. Wind, birds, and squirrels carry it from roof to roof — which is why you'll often see entire neighborhoods develop the same streaking pattern within a few years of each other. Once it establishes on your roof, it grows slowly at first, then accelerates as the colony expands.
Yes — though the damage is gradual. The bacteria feeds on the limestone in your shingles, which accelerates granule loss. Granules are the protective layer that shields the asphalt from UV degradation. As granules are lost, the asphalt beneath becomes brittle and cracks. Studies have shown that untreated Gloeocapsa Magma infestations can reduce an asphalt shingle roof's lifespan by 10–15 years.
The Asphalt Roofing Manufacturers Association (ARMA) recommends a solution of water and laundry-strength liquid chlorine bleach applied at low pressure — what the industry calls "treatmenting." The bleach kills the bacteria at the cellular level. Pressure washing, by contrast, only removes the surface staining while leaving the root colony intact — and physically removes granules in the process, which is why it voids most shingle warranties.
After treatment, the streaks don't disappear immediately. The dead bacteria gradually wash away over several rain cycles — typically 30–90 days. A properly treated roof should remain clean for 3–5 years.
Moss is a non-vascular plant that thrives in cool, moist, shaded environments — which describes the north-facing slopes of most Columbus roofs for much of the year. Unlike algae, moss has root-like structures called rhizoids that physically penetrate and grip the surface they grow on.
When moss grows thick on a roof, it acts like a sponge — absorbing and holding moisture against the roofing material for extended periods. On asphalt shingles, this accelerates granule loss and causes the asphalt to soften and crack. On cedar shakes, trapped moisture causes rot. On slate and tile, it can work into cracks and crevices and cause cracking during freeze-thaw cycles.
The rhizoids also physically lift the edges of shingles as the moss colony expands, creating gaps that allow wind-driven rain to penetrate the roof deck. This is how moss causes leaks — not through the shingle itself, but by lifting it. All the while, adding to the roof's demise.
Many homeowners instinctively try to scrape or brush moss off. This is counterproductive. Dry scraping breaks the moss into fragments, each of which can re-establish as a new colony. It also removes granules from asphalt shingles and can crack brittle tile. The correct approach is to kill the moss first with a biocide solution, then allow it to die and naturally shed over several rain cycles. It's the most gentle way to safely remove moss and lichen from a roof.
Once moss is treated and removed, the roof is free of bio and continues to shed water and shield the interior of the home from the elements as designed. Keeping the roof free from bio helps it live out its projected lifespan and oftentimes, outliving it.
The terms "roof cleaning" and "pressure washing" are often used interchangeably by homeowners — but they describe very different processes with very different outcomes for your roof.
Pressure washing uses high-pressure water (typically 3,0000–4,000 PSI) to blast contaminants off surfaces. It works well on concrete driveways and brick walls — surfaces that can withstand the force. On a roof, that same pressure physically removes the granules from asphalt shingles (the protective layer that shields the asphalt from UV), cracks brittle slate and tile, splits cedar shakes, and can force water under flashing and into the roof deck.
Most asphalt shingle manufacturers — including GAF, Owens Corning, and CertainTeed — explicitly state in their warranty documentation that pressure washing voids the warranty. The ARMA (Asphalt Roofing Manufacturers Association) has published guidelines specifically recommending against pressure washing.
Our gentle cleaning process (typically under 70 PSI — less than a garden hose) delivers a water-soluble biodegradable biocide solution to kill and remove bio-growth. The chemistry does the work, not the pressure. The solution penetrates the bio-growth and kills it at the cellular level — including the root structures that pressure washing leaves behind.
Because our system kills the organism rather than just scalping it away, results last significantly longer: typically 5-7 years versus 6–12 months for pressure washing. This is why all the shingle manufacturer's forbid the use of pressure on the roof. Our gentle process rids the roof of the damaging bio safely without damaging the roof.
A diluted bleach solution (typically 1 part bleach to 2 parts water) applied with a garden sprayer is the DIY version of roof cleaning — and it can work for mild algae growth on shingles. The risks are: over-concentration can damage plant beds and landscaping; it requires working on or near the roof; and it doesn't address moss or lichen effectively without the proper pre-treatment and specific dwell time. For anything beyond light algae staining, professional application is safer and more effective.
We're going to be straight with you here, because we think you deserve an honest answer rather than a sales pitch.
If you have a single-story home with a low-pitch roof, mild algae staining (not moss or lichen), and you're comfortable working on a ladder, you can treat light Gloeocapsa Magma growth yourself. The ARMA-recommended DIY solution is 1 part laundry-strength liquid chlorine bleach to 1 part water, applied with a garden pump sprayer. Pre-wet your landscaping, apply the solution, let it sit for 15–20 minutes, then rinse with a garden hose. Repeat if needed.
A professional treatment for a typical Columbus home runs $700–$2,000. A fall from a roof — even a one-story fall — can result in injuries costing tens of thousands of dollars in medical bills and lost work. The math strongly favors hiring a professional for anything beyond the most accessible, low-pitch sections of a single-story home.
We'll fly a drone over your roof, photograph every problem area, and send you a full report with a no-obligation estimate. Most homeowners are surprised by what they see.