How Siphonic Roof Drainage works

Low Rainfall

At Low Rainfall Siphonic Roof Drainage works similarly to traditional roof drainage.

Design Rainfall

When Design Rainfall occurs, the collecting pipe fills with water - next the water falls at high velocity through the downpipe and sucks the water from the roof. This movement is called Siphonic Action.
The full bore flow and the higher flow velocity in the siphonic pipework result in much smaller pipe diameters than used in a gravity flow system.

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Heavy Rainfall
If water levels increase further due to Heavy or Catastrophic Rainfall, the rainwater must be drained by both the main pipework and by use of an emergency overflow system. This emergency overflow protects the roof from exceeding its designed static load and the risk of collapse.

A second pipe system or special attic outlets with downpipe in the facade area are also common for emergency overflow.

What are the benefits of Siphonic Roof Drainage

Material Saving at Least 75%
90% Less CO2 Footprint

In the life cycle of a building: from the the raw material extraction to the demolition and waste treatment. At every step material and energy are saved.

Mitigate Urban Flooding

Siphonic Roof Drainage takes more time to fill the pipes with rainwater. This controlled delay may take a few minutes. Therefore, Siphonic Roof Drainage cuts the peak runoff into sewer systems and will mitigate urban flooding.

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