go here Republic Polytechnic, Singapore
source url To provide waterproofing membrane protection and efficient sub-soil drainage under llandscaped roof areas on the 20ha site of the campus.
http://bramaintl.com/disqusion/28.html VersiCell lightweight interlocking drainage modules were positioned over Evalon thermoplastic waterproofing membrane, after which a geotextile filter fabric was installed over the drainage modules and growing media placed on the geotextile. VersiCell provided protection to the waterproofing membrane and easily withstood the weight of equipment used during the subsequent installation growing media. VersiCell modules provide the necessary cavity beneath the planted areas to efficiently discharge excess sub-soil water and prevent water-logging on the landscape roof. The resultant lush greenery on the campus grounds has earned the Polytechnic the nickname of “Campus in the Park”.