Glassfibre-reinforced concrete (GRC) is a hi-tech concrete cladding alternative that is versatile and durable, considerably lighter than concrete, with a tensile strength three to four times greater than equivalent steel fibre. Robust, with high impact resistance, GRC cladding panels are much lighter in weight than precast equivalents. Rolfe Judd Architects chose GRC instead of an original suggestion for precast-concrete cladding for the Seamore Project, a six-storey office development on London's Park Lane. 'Fixing a precast cladding system on to the concrete mainframe would have led to cold bridging and U-value problems, ' says director Graham Fairley. 'GRC panels gave us the same tight tolerances as precast, and answered other technical problems for us, eliminating cold bridging, vapour barrier and load issues.' Two different 18mm-thick panel sizes were developed with precast contractor Trent Concrete: a curved column panel 400mm deep x 3m wide; and a larger 1.5 x 5m panel, each fabricated with in situ ribs to prevent twisting or folding. Using GRC panels significantly accelerated construction time, as the cladding system could closely follow the mainframe as it went up.