Measuring Up: Improved Water Monitoring in Retention Roofs

Dr Chris Hambley, a senior associate at Withers & Rogers, talks us through a novel way to improve water monitoring in retention roofs.

“Modern roofs, particularly green and retention roofs, are increasingly designed to actively manage rainwater. Accurate monitoring of water levels within water‑carrying layers of the roof is therefore essential. However, conventional arrangements place water level sensors directly within these layers, where limited space and poor accessibility make correct positioning difficult, often resulting in unreliable measurements.”

“European patent EP4624693B1, granted to Optigrün International AG in May 2026, addresses these challenges using a novel inspection chamber for these sophisticated roof systems. The patent protects an inspection chamber (1) with a side wall (10) defining an interior space (11) which is open at the bottom. The inspection chamber also has a mount (12) arranged in the interior space for a water level sensor (3), and an adjustment device (13) for positioning the mount to optimise positioning of the water level sensor.”

“Instead of installing the sensor within the constrained water layer, the patented invention positions it inside the inspection chamber, where the open base provides direct access to the water surface and greater flexibility in terms of positioning. By enabling precise alignment, the invention improves measurement accuracy and compensates for installation tolerances or uneven roof structures. This also ensures compatibility with different sensor types, such as ultrasonic sensors, capacitive sensors or float sensors. Positioning the sensor within the inspection chamber also improves accessibility for installation and maintenance.”

“The inspection chamber can also house associated electronics for processing and transmitting data, supporting integration into broader, automated water management systems.”

“This patented technology highlights how novel design changes, such as optimising the mounting of a sensor, can significantly improve system performance. By delivering more accurate, reliable and accessible water level monitoring, the invention supports advanced roof water management strategies.”

“In a growing field such as green and retention roofs, securing patent protection enables the patentee to capitalise on these improvements, offering a clear route to competitive advantage in an increasingly sophisticated construction sector.”

For more information visit Withers & Rogers.