When designing roofing drainage systems, choosing the right roof drain is key to safeguarding your building from water damage. The Zurn Z164 combines primary roof drainage and overflow capacity in a single assembly. This guide explains what makes the Z164 a high-quality solution, its core specifications, installation best practices, and includes a case study showing how it performs under real conditions.

Zurn Z164 Schematic

What Is the Zurn Z164?

The Zurn Z164 is a combination roof and overflow drain for flat or low-slope roofs. Its robust cast-iron construction, low-profile dome, and integrated flashing clamp with gravel guards help maintain high flow while resisting debris. The Z164 is designed for commercial, institutional, and industrial applications where reliability and service life are paramount.

Key Features & Advantages

• Dual-Function Design: Primary drainage and overflow protection in a single unit simplifies roof layouts and reduces separate components.
• Durable Build: Cast-iron body and dome for long-term performance in harsh weather conditions.
• Low Silhouette Dome: Helps minimize wind loading and snow accumulation while preserving open area for flow.
• Membrane Compatibility: Combination flashing clamp and gravel guards support watertight integration with common roofing membranes.
• Outlet Flexibility: Multiple outlet sizes and connection types accommodate a wide range of piping schemes.

Zurn Z164 Product View

Where the Z164 Excels

• Commercial roofs (warehouses, offices, healthcare)
• Institutional buildings (schools, municipal facilities)
• Industrial sites with high storm-water events
• Retrofits where combining main and overflow functions simplifies the design

Installation Best Practices

Proper installation ensures that the Z164 delivers consistent performance over decades. Keep the following in mind:

• Locate drains at the low points of roof slopes to prevent pooling.
• Use the integrated flashing clamp for a tight, watertight seal with your membrane.
• Select the outlet size and connection that match hydraulic calculations and the leader system.
• Preserve access for routine maintenance and inspection of the dome and gravel guards.
• Verify overflow pathways during commissioning to confirm storm-event performance.

Zurn Z164 Dimensions Schematic

Case Study: Campus Retrofit with the Z164

Project: A multi-story university building in a region with seasonal heavy rainfall needed to reduce roof overflow incidents and maintenance callouts. Separate legacy overflow drains complicated service and didn’t perform well under storm surges.

Solution: The facilities team retrofitted key roof areas with Zurn Z164 combination drains. Units were positioned at the lowest roof planes, integrated with the existing membrane using the flashing clamp, and paired with appropriately sized no-hub outlet connections.

Results: After the first rainy season, standing-water events were eliminated in upgraded zones. Emergency maintenance decreased significantly, and membrane life is expected to improve due to reduced ponding and edge leaks. The combined main/overflow function simplified inspections and reduced inventory of spare parts.

Maintenance Tips

• Inspect and clear the dome and gravel guards at least seasonally, or more often in leafy environments.
• Verify that overflow pathways are unobstructed before storm seasons.
• Record routine checks in a maintenance log to track performance and plan replacements proactively.

Conclusion

The Zurn Z164 delivers dependable roof drainage and overflow protection in a single, durable assembly. Its cast-iron construction, membrane-friendly clamp system, and flexible outlet options make it a strong choice for new construction and retrofits alike—especially where simplifying components and reducing maintenance is a priority.