Organic growth on a roof refers to living organisms that take root and spread on the roofing surface.
Organic growth on a roof includes various living organisms that can begin to grow and thrive on roofing materials. As referenced, these include mold and mildew to moss and algae. These growths are not merely cosmetic issues; they represent actual plant or fungal lifeforms that can negatively impact the integrity and lifespan of your roof.
Initially, these growths may seem harmless, perhaps just causing discoloration or staining. However, they can cause damage to your roof in the short term. If these organic growths are left unchecked for too long, they can lead to significant issues, potentially causing thousands of dollars worth of damages.
Common Types of Organic Growth
Understanding the specific types of growth helps in identification and treatment.
- Algae: Often appearing as dark, black, or greenish streaks. The most common type is Gloeocapsa magma, a blue-green algae.
- Moss: Typically presents as green, fuzzy, or mat-like patches. Moss has roots (rhizoids) that can attach firmly to shingles.
- Mold: Can appear in various colors (black, green, white) and textures. Mold growth often indicates underlying moisture issues.
- Mildew: Often seen as a powdery or downy surface growth, typically white, gray, or yellowish. It's similar to mold and often an early stage of fungal growth.
| Growth Type | Typical Appearance | Primary Concern |
|---|---|---|
| Algae | Dark streaks | Discoloration, retains moisture |
| Moss | Green, fuzzy patches | Lifts shingles, traps moisture, potential decay |
| Mold | Varied colors/textures | Discoloration, potential health issues, indicates moisture |
| Mildew | Powdery patches | Discoloration, surface growth |
Why Organic Growth Occurs on Roofs
Roofs provide an environment conducive to the growth of these organisms, especially those on the north-facing side or under trees. Factors contributing to their growth include:
- Moisture: Rain, humidity, and poor drainage provide the water needed for growth.
- Shade: Shaded areas stay wet longer, preventing the roof surface from drying out.
- Debris: Accumulated leaves, needles, and dirt provide nutrients and retain moisture.
- Roof Material: Shingles, especially asphalt, contain materials that some algae and moss feed on.
Impact and Damage
The presence of organic growth can lead to various problems:
- Moisture Retention: Moss and thick algae mats trap water against the roof surface.
- Material Deterioration: Trapped moisture can cause asphalt shingles to degrade, granules to detach, and wooden shakes to rot. Moss roots can lift shingles, making them vulnerable to wind and water penetration.
- Energy Efficiency: Dark algae streaks absorb more heat, potentially increasing cooling costs.
- Curb Appeal: Visible growth makes a roof look old and poorly maintained, decreasing property value.
Addressing organic growth promptly is crucial to prevent minor issues from escalating into significant, costly roof damage.
Solutions and Prevention
Removing organic growth and taking preventative measures can extend your roof's lifespan:
- Cleaning: Gentle washing with appropriate cleaning solutions (specific roof cleaners, or diluted bleach/copper sulfate solutions - use with caution and proper safety). Avoid high-pressure washing, which can damage shingles.
- Professional Services: Hiring professionals ensures the job is done safely and effectively without damaging the roof.
- Trim Trees: Cut back branches overhanging the roof to reduce shade and falling debris.
- Install Zinc or Copper Strips: Placed below the ridge, these metal strips release particles when it rains that are toxic to algae and moss as the water flows down the roof.
- Choose Resistant Shingles: Some new asphalt shingles are manufactured with algae-resistant granules (containing copper).
By understanding what organic growth is and taking steps to manage it, you can protect your investment and maintain your roof's health and appearance.
