Roof Maintenance Services LLC

Across North America, climates make conditions just right to give roofs a distinctive dark “watermark” stain—a telltale sign of blue-green algae growth.

Although the blue-green algae won’t damage your roof, it can leave potential buyers thinking that a roof is old or damaged, which can reduce the home’s value. Roof algae removal can be difficult without damaging shingles, so expect homeowners to leave it to the professionals.

Blue-green algae is a cyanobacterium called Gloeocapsa magma that travels through the air. It is more prevalent in warm, wet climates. Because it travels easily, the stains often affect whole neighborhoods. In an effort to shield themselves from the sun, the blue-green algae surround themselves with a brownish-black shell that causes roofs to appear dark and stained. Unlike moss or tree droppings, which typically produce only localized discoloration, algae discoloration may be uniform or appear as streaks on the roof.

GAF has developed industry-leading technology to provide homeowners with a product that helps protect against blue-green algae growth. Let’s walk through everything contractors need to effectively sell GAF Time-Release Algae-Fighting Technology.

Benefits of GAF Time-Release Algae-Fighting Technology

For years, shingle manufacturers have added copper to roof granules to help prevent blue-green algae growth. As the roof dampens during rainfall, the copper leaches out of the granules and helps prevent blue-green algae growth. As the copper is used up, the protection wanes. After developing specially engineered capsules that release copper steadily over time, GAF is able to provide customers with a 25-year StainGuard Plus™ Algae Protection Limited Warranty* on many of its most popular products .

In a 2021 GAF survey** of 500 homeowners, 87% said they found protecting their roof from blue-green algae very or extremely important. GAF is able to respond to that customer demand by providing this new technology. 

StainGuard Plus Algae Protection Limited Warranty

GAF has developed proprietary technology that infuses special capsules with thousands of copper microsites to provide a controlled release of copper that helps prevent blue-green algae growth.

This technology allows GAF to provide homeowners with a 25-year StainGuard Plus™ Algae Protection Limited Warranty* against blue-green algae discoloration. The GAF StainGuard Plus™ Limited Warranty* comes with a variety of shingles, including architectural, designer, ridge caps, and visible starter strips.

Customer Talking Points

These talking points can be used to educate your customers about blue-green roof algaeand help them decide if products with GAF Time-Release Algae-Fighting Technology are right for their roof.

• Many homes in North America and Canada suffer from blue-green algae discoloration. It mostly affects warm and wet climates.
• Although blue-green algae won’t damage the roof or shingles, the dark stains can affect home resale values.
• The dark staining caused by blue-green algae growth may reduce the effectiveness of cool roofs.
• Blue-green algae-stained roofs can be cleaned with a bleach solution to help lighten the stain and prevent the algae’s spread to other roofs. The Asphalt Roofing Manufacturer’s Association recommends using a solution of equal parts chlorine bleach and water but advises that directions for mixing them may vary depending on the shingle manufacturer and the amount of discoloration. The group suggests getting the approval of the manufacturer before trying other cleaning chemicals or methods.
• Blue-green roof algae removal is best done by a roofing professional to avoid shingle damage.
• Regular maintenance, gutter cleaning, and tree trimming can help reduce blue-green algae growth.
• The Asphalt Roofing Manufacturer’s Association™ does not recommend adding zinc or copper strips to an existing roof. Doing so requires breaking the sealant bond to place the strips. If not installed correctly this may leave exposed nails resulting in wind damge and leaks.

*25-year StainGuard Plus™ Algae Protection Limited Warranty against blue-green algae discoloration is available only on products sold in packages bearing the StainGuard Plus™ logo. See GAF Shingle & Accessory Limited Warranty for complete coverage and restrictions, and qualifying products.

**Based on 2021 survey commissioned by GAF of 500 homeowners in areas with moderate to high amounts of blue-green algae.