Roof algae isn’t just an eyesore

If you’ve noticed dark streaks or blotchy patches spreading across your shingles, it’s not just dirt—it’s likely roof algae, and it’s more than a cosmetic issue. In Norfolk’s humid coastal climate, algae can grow quickly, especially on shaded roofs. And while it might start out as a visual nuisance, over time it can compromise the performance and lifespan of your roof.

Knowing how to identify it, why it matters, and when to act can help you avoid expensive repairs—and keep your roof looking its best. Let’s break it down.

What exactly is roof algae?

The most common type of roof algae is Gloeocapsa magma, a blue-green algae that thrives in humid environments like southeastern Virginia. It typically appears as:

• Dark black or greenish streaks
• Blotchy or streaky patches
• Growth on the north- or east-facing parts of your roof
• Discoloration that spreads over time

Algae feed on the limestone filler used in many asphalt shingles. As they multiply, they hold moisture on the surface of your roof, which can worsen other issues—especially when combined with Norfolk’s regular rainfall and salt air.

Why roof algae is a real problem

A little discoloration might not seem urgent—but roof algae can silently cause long-term damage. Here’s why you shouldn’t ignore it:

• Shortens shingle lifespan

Algae slowly degrade shingles by feeding on the limestone granules. This weakens your roof’s ability to deflect UV rays, hold up to storms, and insulate your home.

• Attracts moss and lichen

Algae create the ideal damp conditions for moss and lichen to grow. These organisms can lift shingles, trap even more moisture, and increase the risk of leaks.

• Hurts curb appeal and resale value

Dark streaks and splotches can make your home look older and poorly maintained—potentially turning off buyers during a sale.

• Impacts energy efficiency

Algae-darkened shingles absorb more heat, especially during summer, which can drive up your cooling costs.

How to stop roof algae before it spreads

Dealing with algae early makes all the difference. Here’s what you can do as a homeowner:

✅ 1. Schedule a professional roof inspection

The first step is knowing what you’re dealing with. Experienced roofers in Norfolk VA can confirm if it's algae, moss, or something more serious—and give you the safest plan of action.

✅ 2. Don’t pressure wash it

High-pressure water can blast granules off your shingles, causing more damage than good. Instead, opt for soft-washing methods that use low pressure and cleaning solutions.

✅ 3. Use a gentle algae-removal solution

Many pros use biodegradable roof cleaners that kill algae without harming your shingles or landscaping. Avoid bleach or harsh DIY mixes—they can corrode gutters and void your warranty.

✅ 4. Improve sunlight exposure

Trim back overhanging branches to reduce shade and let your roof dry out faster. Algae thrive in damp, dark areas.

Preventing future algae growth

Once your roof is clean, you can take steps to stop algae from coming back:

• Install copper or zinc strips at the roof ridge. Rainwater carries the metal ions down the roof, killing algae as it forms.
• Opt for algae-resistant shingles when replacing your roof. These shingles have copper granules embedded to prevent growth.
• Keep gutters clean and ensure proper drainage to prevent standing moisture.
• Schedule regular inspections, especially after storm season or in high-humidity months.

When to call roofers in Norfolk VA

If you’re unsure whether it’s time to act, here are some clear signs you should get help:

• Black streaks are growing larger or spreading
• Your roof looks patchy, even after it rains
• There’s visible moss or lichen forming
• You’re planning to sell your home soon and want to boost curb appeal
• It’s been more than a year since your last roof inspection

Local pros like WT Anderson Roofing know what to look for and how to treat algae without damaging your shingles. We’ve helped countless homeowners throughout Norfolk extend the life of their roof with smart, affordable maintenance.

Trust WT Anderson for safe, lasting roof care

Roof algae isn’t something to panic over—but it’s definitely not something to ignore. With the right care, your roof can stay clean, strong, and visually appealing for years to come. Whether you need a simple soft wash or a full roof replacement, WT Anderson is here to help.

As leading roofers in Norfolk VA, we specialize in protecting homes from algae, moisture, and all the challenges that come with living in a coastal climate.

See algae streaks on your roof?
Schedule a roof inspection with WT Anderson and let Norfolk’s most trusted roofing team keep your home in top shape.

Sources:

• Asphalt Roofing Manufacturers Association – Algae and Roof Stains
• Energy Star – Cool Roof Technologies

‍