Appearance problems on a roof are easy to overlook, especially when everything appears in good condition. However, biological growth on roofs is a real concern that can lead to bigger issues if ignored. At Precision Roofing, we help property owners recognize the signs early and take the right steps through regular inspections and preventative maintenance.
What Is Biological Growth on Roofs?
Biological growth on roofs typically includes moss, algae, weeds, grass, or flowers, especially on flat or low-slope commercial roofs. These organic materials thrive in areas where moisture accumulates and drainage is poor.
Where Does It Come From?
Over time, wind carries dirt, seeds, and organic debris onto the roof. When drains aren’t cleaned out regularly, all that debris settles in the low points. That’s where water naturally flows, carrying sediment along with it. If the drains are blocked by sticks, leaves, or even soccer balls and other debris (common on school roofs), the moisture sits and creates ideal growing conditions.
Why Clogged Drains Lead to Growth and Bigger Problems
When drains get blocked and water can’t escape, it creates a chain reaction. Here’s what happens:
- Water pooling: Standing water accelerates the breakdown of roofing materials and increases the likelihood of biological growth.
- Debris buildup: Dirt and debris settle around the clogged area, becoming planting beds for weeds and grass.
- Blocked flashings: Most flashings are only 6 to 8 inches above the roof deck. If water rises above that level, it can bypass the flashings and enter the building.
- Interior damage: Backed-up water can leak through walls, ceilings, and HVAC penetrations, causing interior water damage.
These issues aren’t just cosmetic; they compromise the roof’s ability to protect your property.
Signs of Biological Growth on Roofs
Some signs are visible from the ground, while others require a roof inspection. Look for:
- Overflowing scuppers (a clear sign of a clogged drain)
- Discolored patches or vegetation growing at drain points
- Damp spots that don’t dry even in warm weather
- Evidence of interior leaks after rainfall
If you see any of these, it’s time to act.
How Often Should Roof Drains Be Cleaned?
We recommend cleaning your commercial roof drains at least every six months. Following that schedule can help stop biological growth before it starts. For buildings surrounded by trees or those with frequent rooftop activity, such as schools, cleaning the drains every quarter may be a better option.
It’s also smart to check after major storms or wind events, since flying debris often ends up on the roof.
Our Commercial Roof Maintenance Services
At Precision Roofing, we offer commercial roof maintenance plans tailored to your needs, whether that’s quarterly or annual service. Here’s what we include:
Routine Drain and Scupper Cleaning
We remove debris, clear blockages, and flush out roof drains so water can flow freely. This is the first and most important step in controlling biological growth on roofs.
Resealing and Repairs
We inspect and reseal counter flashings, top off pitch pans, and address any small issues before they grow into larger problems.
Full Roof Inspections
Our team walks the entire roof, checking for signs of damage, standing water, and other issues. We create a full report and document any maintenance needs.
Custom Maintenance Plans
We’ll set up a recurring maintenance schedule that fits your building’s size, location, and exposure level. This proactive approach helps you extend the life of your roof and avoid emergency repairs.
Key Takeaways
- Biological growth on roofs is caused by trapped moisture and debris, especially around clogged drains.
- It can lead to structural damage, interior leaks, and even roof failure when not addressed.
- Drains should be cleaned at least twice a year to prevent buildup and biological growth.
- Visible vegetation, overflow from scuppers, or consistent dampness are signs that maintenance is overdue.
- Precision Roofing provides customized commercial maintenance plans to keep your roof in top shape year-round.
Ready to Schedule Roof Maintenance?
If you’ve noticed signs of biological growth on your roof or want to avoid them entirely, contact our team. We’ll assess your roof, clean it thoroughly, and recommend a service plan that protects your building long-term.
