The Roof Drain with Overflow (Zurn 100C) is engineered to handle heavy stormwater loads while offering contractors and designers flexibility in drainage routing. With a dual-outlet system, it provides both increased hydraulic capacity and built-in redundancy for added safety. This blog explores the Zurn 100C Roof Drain with Overflow in detail: its design, benefits, installation best practices, and a real-world case study that highlights its effectiveness.

Roof Drain with Overflow – Installation Schematic

What Is the Roof Drain with Overflow?

The Zurn 100C Roof Drain with Overflow features a dual-outlet design that allows water to exit through two independent discharge paths. This setup provides system backup, better flow distribution, and greater reliability for roofs exposed to intense rainfall. Its durable construction supports both load requirements and long-term drainage performance for commercial and industrial projects.

Key Features & Benefits

• Dual Outlet Design: Two discharge paths boost hydraulic capacity and add system redundancy.
• Durable Construction: Made from high-quality materials that resist weathering and ensure long service life.
• Strainer or Dome Options: Prevent debris entry while maintaining strong flow.
• Flexible Integration: Multiple outlet sizes and connection types fit a variety of piping layouts.
• Reliable Safety: Dual outlets help reduce the risk of overflow or failure if one path is blocked.

Zurn Brand Reliability

Applications & Use Cases

• Commercial rooftops with high stormwater demands
• Industrial sites exposed to frequent heavy rainfall
• Institutional facilities requiring redundant systems (schools, hospitals, labs)
• Projects where splitting flow helps optimize downstream piping
• Retrofit projects to strengthen existing drainage capacity

Installation Tips & Best Practices

For best results, proper installation of the Roof Drain with Overflow requires:

• Placing the drain at the roof’s lowest point with correct slope alignment.
• Balancing outlet sizes and piping for even distribution.
• Installing a dome or strainer to prevent clogging from debris.
• Carefully sealing the flashing clamp or membrane to maintain waterproofing.
• Testing both outlets under load conditions to confirm proper operation.

Roof Drain with Overflow – Technical Schematic

Case Study: Multi-Tenant Office Complex

Challenge: A large office complex faced recurring roof overflow problems during heavy storms. Its single-outlet drains were vulnerable to blockages, creating risks for tenants and building operations.

Solution: Engineers replaced the old drains with Zurn Roof Drains with Overflow. Each unit directed flow into two separate piping paths, increasing both hydraulic capacity and system reliability.

Outcome: Over multiple rainy seasons, the building saw no overflow incidents. Even when one outlet required servicing, the second outlet maintained performance. This improved reliability while lowering maintenance costs.

Conclusion

The Roof Drain with Overflow is an excellent choice for demanding roof drainage projects. With its dual-outlet design, rugged construction, and proven ability to balance flow, it is well-suited for commercial, industrial, and institutional applications. When properly installed and maintained, it delivers safety, redundancy, and peace of mind for years.