Surrey Central City - Atrium Facade
Central City's North Façade is a great sweeping, timber-supported glass wall 86 feet high and 256 feet long, divided at mid-height by a concrete canopy. Bing Thom Architects designed it to take the shape of an irregular curve, with a 4 degree tilt from vertical to minimize exterior reflections. StructureCraft's involvement early in the design phase led to an uncompromised and fully resolved design.
Large Parallam mullion columns spaced at 24 foot centres support the lower façade glazing as well as the concrete canopy above it. The upper façade, while similar, utilizes a series of smaller but more frequent columns, which rise from the canopy to meet the Atrium Roof.
The supporting columns for the lower façade are 46 feet long, 24 inches in diameter, and had to be custom turned and tapered to millwork quality. When discussions with potential suppliers failed to provide a reliable, economic solution, we decided to turn the logs ourselves. This decision allowed us to control our future costs while ensuring that we could deliver these crucial components on time and to exacting specifications.
Supporting tall glass walls presented its own set of design challenges. In addition to the irregular curve and tilt on the façade, the glazing required a very small margin of error, no more than plus or minus one-eighth of an inch for the slightly trapezoidal glass panels. Moreover, glass cannot be stacked 46 feet high, so we devised a series of fine spring-loaded stainless steel cables to balance the load.
The glass wall is braced by tapered Parallam arms that reach out from the columns and connect to similar muntins that carry the glazing. After pondering with the architect the problem of how to connect these refined pieces, we decided traditional connectors would not be visually acceptable, and so set out to test some ideas we had.
Working with brushed aluminum, we custom-designed and load-tested a nearly invisible plate-and-pin system. This, in turn, required design for new hydraulic tools to install the tight-fitting pins. The system allowed us to erect the façade frame quickly and efficiently while meeting the tight tolerances.
The large column connections to the concrete base and canopy also needed streamlining. Working with the architects, we modelled a sleek casting design to carry the 220,000 pound design load.
Taking a Creative Approach to Problems – the magnitude of forces required very large timber columns, and their finish had to be virtually furniture quality. When we couldn't find a supplier, we chose to design and build our own lathe, one of the largest of its kind in North America. That lathe is now the centerpiece of our millwork division.