The Hangzhou Sports Park, China’s largest stadium project this decade, features a grand structure with alternating steel and polycarbonate flower-petals encircling the bowl’s perimeter. Strong winds – and even typhoons – are common in Hangzhou and the roof was required to withstand wind loads of 310 kg/sqm. Palram designed an aluminum joiner for connecting the polycarbonate sheets, and a wind tunnel test was required prior to approval. Some sheets were more than 18 meters long and required specially constructed wooden crates. “Shorter” 15 m sheets, were shipped bent into a “roller coaster” shape within standard containers. At some points the roof's slope is close to zero degrees. Palram designed a special aluminum profile with a rubber gasket directing the water flow towards the gutter for proper drainage. One other advantage of the Sunpal system is the fact that proprietary T-fasteners fix the joined panels to the structure, thereby avoiding any fastener penetration through the panels, for additional protection against water leakage.