Wooden roof elements bear their long spans on a bow string steel truss
The architect and principal engineering office Price & Myers sought an efficient, lightweight solution for the wide span. Traditional laminated timber, combined with a solid wooden panel on top of, was found to have a height of 1200 millimeters for the beams, which was much too high.
The engineers at Price & Myers contacted Metsä Wood to look at a design with a shallower construction for the roof, but that would still accommodate the large span and heavy green roof.Following a joint design effort, they agreed a roof design with Kerto-Ripa elements. These elements are made from Kerto LVL using structural gluing. With any other material, trusses would have had to be more densely spaced.
The Kerto-Ripa elements constitute the vaulted roof construction are 12.9 meters long and have a total height of 645mm and maximum width of 1200 millimeters. To accommodate the curve of the structure four different widths were determined 550 mm, 600 mm 700 mm, and 1200 mm, totalling 140 prefabricated Kerto-Ripa elements. The roof elements fit flush with the vaulted, spaced, bowstring steel truss. To get the steel element the same depth as the Kerto-Ripa elements (645 millimeters), the steel manufacturer was heavily involved.