What Are Those Black Stains on the Roof?
Those unsightly black stains on your roof are caused by algae. Algae appear as dark stains on shingles, typically covering more area on the lower sections of the roof and tapering as they reach the ridge.
How Does a Roof Get Algae?
Algae spread via airborne spores from one infected roof to another. These spores land randomly on a roof and take root, forming a protective sheath that creates the dark color, shielding the algae from UV rays.
How Does Algae Grow?
Algae require moisture and proper temperatures to thrive. Dew is the primary moisture source. Algae are found predominantly in the Southeast, but they can grow nationwide, especially on the northern exposures of roofs, which receive less sunlight. Algae are well adapted to extreme conditions.
Solutions for Algae Staining
Install Algae Resistant Shingles
Consider installing algae-resistant shingles, such as those offered by GAF. These shingles have specially formulated granules that inhibit algae growth, keeping your roof looking new for years.
Cleaning an Existing Roof
If installing a new roof is not an option, clean the roof with a special mixture:
- Ingredients: 4 gallons (18.2 L) of water, 1 gallon (4.5 L) of bleach, and 1 cup (236 mL) of TSP (Tri-Sodium Phosphate or an acceptable phosphate-free substitute).
- Application: Apply the mixture with a garden sprayer, let it sit on the roof surface for up to 20 minutes, and rinse with low-pressure water. Protect any shrubs below, and be cautious as the roof surface will become slippery when wet.
What NOT to Do
Do not power wash the shingles to clean them. Some roof cleaning companies offer this service, but it is not recommended as it may dislodge granules, leading to premature shingle failure.
Recommended GAF Shingles for Algae Resistance
GAF Shingles with Advanced StainGuard Plus™ Protection Available Nationwide:
- Timberline Ultra HD®
GAF Shingles with StainGuard® Protection Available Nationwide:
- All GAF Lifetime Designer Shingles except Grand Sequoia®
- Timberline Cool Series®
- Grand Sequoia® ArmorShield™
- Timberline® ArmorShield II™
- Timberline® American Harvest®
GAF Shingles with StainGuard® Protection Available in Select Areas:
- Grand Sequoia®
- Timberline HD®
- Timberline® HDZ™
- Timberline® Natural Shadow®
- Royal Sovereign®
Note: StainGuard® protection applies only to shingles with StainGuard®-labeled packaging. StainGuard Plus™ protection applies only to shingles with StainGuard Plus™-labeled packaging. See the GAF Shingle & Accessory Ltd. Warranty for complete coverage and restrictions.
Conclusion
Algae staining on shingles is a common issue that can be managed effectively with the right approach. Installing algae-resistant shingles or using a proper cleaning solution can help maintain the aesthetic and functional integrity of your roof.
For Immediate Service or Consultation
Contact Allied Emergency Services, INC.
Phone: 1-800-792-0212
Email: Info@AlliedEmergencyServices.com
Location: Serving Illinois, Wisconsin, and Indiana with a focus on the greater Chicago area.
If you require immediate assistance or have specific questions, our human support is readily available to help you.
Disclaimer: This article is intended for informational purposes only. For professional advice, consult experts in the field.
