Why is There Moss and Algae on the North-Facing Side of My Long Island Roof?

Moss is common on north-facing roof slopes on Long Island because of limited sunlight and excess moisture. Unlike the southern slope of your roof, which sees direct UV light, the north side is typically damp and shaded. In areas of Suffolk County, moss and algae thrive because of high humidity and coastal air.

Long Island’s Climate and Your Rooftop

Long Island is surrounded by water, and ambient humidity levels are consistently higher than in the inland areas of New York. Moisture is a problem, even when it isn’t raining. Spring and fall see heavy morning dew and fog. In wooded areas like Stony Brook and Huntington, the moisture can sit on shingles until the late afternoon.

Consistent dampness creates the perfect conditions for algae and moss. If you have significant tree coverage on your property, moss and algae are more likely. Trees can provide shade and protection from wind, but organic debris that falls on the rooftop becomes a nutrient source for moss.

Understanding the Difference Between Algae and Moss on Your Roof

While algae and moss might look similar from a distance, it’s important to distinguish between these common growths on Long Island rooftops.

• Gloeocapsa Magma is what many people refer to as algae, but it’s actually a type of cyanobacteria. It’s usually flat, dark green, and could have black streaks and stains. It feeds on the limestone filler used in roofing shingles and can increase the risk of shingle granule loss and heat absorption. Allowing this streaky contaminant to spread can reduce the lifespan of your roof.
• Roof Moss is a plant-like organism. It comes in a variety of green and pale-white hues and appears spongy on the surface. Moss is a serious problem that can lead to roof damage and costly roof repairs. The shallow root system in moss works as a sponge, holding moisture directly against shingles. Trapped water can expand and contract during the winter freeze-thaw cycle, cracking shingles or rotting the roof deck.

A local roofing contractor on Long Island can help with scheduling moss and algae removal. Don’t be tempted to pressure wash your roof. This can cause severe shingle damage and moisture problems. Professional cleaning applies safe chemicals to the roofing surface to eliminate bacteria and plant growth without damaging the roofing system.

How Can You Prevent Algae and Moss on Your Roof?

The best way to prevent algae and moss starts with a professional roof installation. Experienced Long Island roofers use climate-appropriate materials to help inhibit organic growth.

High-quality products, like Owens Corning® roofing shingles, are designed to resist organic growth. With special granules that contain materials like copper and zinc, each individual component of the roofing system inhibits organic activity.

If it isn’t time to replace your system with a new roof installation, you could add zinc strips to your roof. These metallic strips can be retrofitted during roof cleaning or roof repair. They release zinc ions to inhibit bacteria and organic growth.

Concerned About Your Roof? Talk to the Best Roofing Contractor on Long Island

Ignoring moss and algae on your roof could invalidate your insurance coverage. It’s time to act.

Renew Roofing Solutions is your local roofing contractor on Long Island. We understand the unique environmental challenges faced in Suffolk and Nassau Counties, and can offer solutions to remove algae and moss, and prevent the problem from coming back.

Start with a detailed roof inspection by calling us at 516-212-0307 or 914-415-7702 today.