Your Roof Has Moss or Algae

Moss and algae on your roof are more than just cosmetic issues—they can impact the long-term health and lifespan of your roofing system. In Pittsburgh, where we experience frequent rainfall and high humidity, it’s not uncommon for homeowners to notice unsightly green or black streaks on their shingles. While these may appear harmless at first, allowing moss and algae to grow unchecked can lead to more serious roofing problems down the road.

So, if you’ve noticed moss or algae on your roof, here’s what you need to know and what you should do about it.

What’s the Difference Between Moss and Algae?

Before we dive into solutions, it's important to understand the difference between moss and algae, as they require slightly different approaches to treatment.

Moss: A small, non-vascular plant that thrives in shaded, moist areas. It grows on the surface of your shingles and has roots that can lift and displace roofing materials. Moss retains moisture, which can lead to roof decay and increased risk of leaks if left untreated.

Algae: A fungus-like organism that appears as black or dark green streaks on your roof, often along the roof’s lower slopes. Unlike moss, algae do not have roots that penetrate shingles, but their growth can still cause staining and shorten your roof's lifespan by holding moisture against the surface.

Why Does Moss and Algae Grow on My Roof?

Moss and algae thrive in areas with:

Moisture: Roofs that are shaded by trees, or that have poor ventilation, tend to stay damp, creating a perfect environment for moss and algae to grow.
Lack of sunlight: Roofs that are shaded for extended periods are more likely to accumulate moisture, increasing the chances of moss or algae formation.
Debris: Accumulated leaves, twigs, and other debris trap moisture on the roof, allowing algae and moss to flourish.

In Pittsburgh, these conditions are common due to our rainy weather and dense tree coverage, making moss and algae a recurring problem for homeowners.

Why Is It Important to Address Moss and Algae Growth?

While moss and algae may seem like harmless growths, they can cause significant issues for your roof:

Damage to Shingles: As moss grows, its roots embed into the shingles, which can lift or damage them over time. This can allow water to infiltrate, causing leaks and costly repairs.
Clogged Gutters: Moss and algae can break down and clog gutters, causing water to overflow and potentially damage your foundation or landscaping.
Shortened Roof Lifespan: The moisture retained by moss and algae can accelerate the deterioration of roofing materials, especially asphalt shingles, leading to the need for early roof replacement.
Aesthetic Issues: Beyond the functional problems, moss and algae are unsightly and can detract from the curb appeal of your home.

How to Get Rid of Moss and Algae on Your Roof

If you’ve noticed moss or algae on your roof, it’s important to address the issue as soon as possible. Here’s how to effectively handle it:

1. Use a Moss and Algae Cleaner

There are many commercial moss and algae cleaners available that are designed specifically for roofs. Look for products that contain sodium hypochlorite or potassium salts of fatty acids, which are effective at killing moss and algae without damaging your shingles.

To use the cleaner:

Follow the manufacturer’s instructions carefully.
Apply the solution to the affected areas, and allow it to sit for at least 15 minutes before rinsing.
Use a gentle stream of water to rinse the roof clean, as high-pressure water can damage shingles.

2. Scrape Off Moss Carefully

For moss growth, it may be necessary to gently scrape the moss off your shingles. You can use a soft-bristled brush or a plastic scraper to avoid damaging the roofing material. Never use a metal scraper or hard brush, as these can cause irreversible damage to the surface of the shingles.

3. Install Zinc or Copper Strips

Prevent future growth of moss and algae by installing zinc or copper strips near the ridge of your roof. As rainwater washes over these strips, it will release trace amounts of metal that inhibit moss and algae growth. This method is especially effective for roofs in shaded areas.

4. Trim Trees and Improve Roof Ventilation

To prevent moss and algae from returning, consider trimming any overhanging branches that block sunlight and trap moisture on your roof. Additionally, improving roof ventilation will help your roof dry out more quickly after rainfall, reducing the likelihood of moss and algae formation.

When Should You Call a Professional?

While DIY methods can be effective, some cases of moss or algae growth may be more serious or difficult to address on your own. Here are a few signs it’s time to call a professional roofing contractor like Gerken Roofing:

Severe damage: If moss or algae have caused significant damage to your shingles or have affected the structure of your roof, professional repairs may be necessary.
Hard-to-reach areas: If your roof has steep slopes or you are uncomfortable working at height, it’s best to leave the cleaning and repairs to professionals.
Ongoing issues: If moss or algae continue to return even after you’ve cleaned your roof, a roofing expert can help assess the underlying causes and offer long-term solutions.

Protect Your Roof with Gerken Roofing

At Gerken Roofing, we understand the challenges that Pittsburgh homeowners face with moss and algae growth. Whether it’s removing existing growth, repairing damaged shingles, or providing preventative treatments, our team has the expertise to keep your roof in top shape.

Regular maintenance and professional inspections are key to avoiding costly repairs and ensuring your roof lasts for years to come. If you’re dealing with moss or algae on your roof, don’t wait until it becomes a bigger problem. Contact Gerken Roofing today for a consultation and ensure your roof stays healthy and beautiful year-round.