Geberit Pluvia, a proven siphonic roof drainage system has helped the Wollongong Hospital create additional space in their carpark. The clever siphonic roofing solution from Geberit lessened the need for piping in Wollongong Hospital’s carpark redevelopment with the number of downpipes reduced by 90% from 26 to only two, helping create more space for car parking.

The innovatively designed Geberit Pluvia siphonic drainage system overcame design and cost challenges, to deliver multiple benefits. The hospital achieved savings in installation costs thanks to a significant reduction in penetrations through the concrete slabs for downpipes and roof outlets. The pipes were laid flat to maximise ceiling height and carpark capacity. The minimal number of downpipes further reduced the risk of damage in high traffic areas.

Conventional drainage systems require equal volumes of air to pass through the pipe when draining water from roofs; this limits the velocity and volume of water, resulting in larger pipe sizes. A Pluvia siphonic drainage system prevents air from entering the system with a suction developing within the pipework to increase velocity and quickly drain large volumes of rainwater from the roof through the pipework into the stormwater system.

The Pluvia outlet design combines with the robust HDPE pipes to increase the flow capacity at each outlet. The flow velocity within the system increases the efficiency of rainwater drainage significantly. Pluvia outlets have a capacity of up to 100 L/s, reducing the number of outlets required when compared to a conventional drainage system. The HDPE pipework is capable of withstanding high negative pressures and flowrates resulting in fewer downpipes and smaller diameters than a conventional drainage system. Since fewer pipes had to be installed in the hospital project, the number of bollards required for protection against impact damage in car parking accidents was also reduced.

Overall, Geberit Pluvia siphonics saved 500m of pipe and more than 200 manhours of labour.

Troy Williams, Project Manager, DM Plumbing:

“Geberit’s innovative piping solutions appealed to us as it significantly reduced the number of downpipes from 26 to just 2, which was one of the determining factors in our winning the contract. They solved our construction, practical and design issues.”