The Roof Overflow Drain (Zurn 100C) is engineered to provide extra protection against roof flooding during heavy rainfall events. Featuring a dual-outlet design, this drain ensures greater hydraulic capacity while delivering built-in redundancy in case one outlet becomes blocked. In this blog, we’ll explore the Zurn 100C Roof Overflow Drain’s design, benefits, installation practices, and a case study that demonstrates its reliability in action.

Roof Overflow Drain – Installation Schematic

What Is a Roof Overflow Drain?

A roof overflow drain serves as a backup drainage solution, reducing the risk of ponding water or structural stress during storms. The Zurn 100C uses two discharge outlets, allowing water to flow through separate paths. This redundancy ensures safer water management and protects building interiors from water intrusion in the event of a blockage.

Key Features & Benefits

• Dual-Outlet Design: Splits water into two independent discharge paths for added safety and performance.
• Durable Materials: Built with heavy-duty construction for long-term reliability in harsh conditions.
• Dome or Strainer Options: Keep debris out while maintaining high water intake.
• Adaptable Integration: Available in multiple outlet sizes and connection styles to fit diverse system layouts.
• Reduced Risk: Helps prevent overflow and structural damage by providing a secondary drainage route.

Zurn Brand Reliability

Applications & Use Cases

• Commercial rooftops requiring reliable overflow protection
• Industrial facilities exposed to frequent heavy rain
• Institutional buildings (schools, hospitals, labs) where redundancy is essential
• Retrofits upgrading older drainage systems to meet modern codes
• Projects needing enhanced stormwater safety and flow distribution

Installation Tips & Best Practices

To ensure the roof overflow drain performs correctly:

• Install at the lowest point of the roof where water naturally collects.
• Select appropriate outlet sizes to balance both discharge paths.
• Use dome or strainer covers to prevent clogging by debris.
• Ensure a watertight seal at flashing and membrane connections.
• Conduct flow tests during commissioning to confirm both outlets function properly.

Roof Overflow Drain – Technical Schematic

Case Study: Multi-Tenant Office Complex

Challenge: A large office complex experienced roof ponding and overflow issues during heavy rainfall. Single-outlet drains made the system vulnerable to blockages.

Solution: Engineers installed Zurn Roof Overflow Drains at critical drainage zones. Each drain split flow between two outlets, improving hydraulic performance and creating built-in backup protection.

Outcome: After two rainy seasons, the building reported zero overflow problems. Even during maintenance on one outlet, the second outlet continued to carry flow, reducing downtime and ensuring system reliability.

Conclusion

The Roof Overflow Drain (Zurn 100C) is a proven solution for protecting rooftops from flooding risks. With its dual-outlet redundancy, durable construction, and adaptability, it is well-suited for commercial, industrial, and institutional projects. When installed and maintained properly, it ensures dependable drainage and long-term peace of mind.