Occupying half a city block with road frontages on three boundaries, 20 Customhouse Quay (XXCQ) is a landmark building on Wellington’s waterfront.

The 14-level NZGBC 5 Star Green Star rated building sets a new standard in safety, value and design.

XXCQ has been designed to minimise structural damage in a 1 in 500 year earthquake  and is estimated to meet up to 180 percent of the Building Code.

It features a diagonally-braced steel diagrid perimeter structure with base isolation, representing a new generation of safety and resilience. The base isolation system also reduces the likelihood of structural damage, increasing the building's lifecycle and reducing its environmental cost.

The distinctive diagrid steel structure is stronger than conventional tower frames but uses approximately 20 percent less steel than conventional building designs. The perimeter diagrid design eliminates all bracing elements from the floorplate, an efficiency that allowed large, open floor areas internally.

Each part of the diagrid structure is unique - every detail required precision due to the complex and unique design angles of the steel diagrid structure. We used our HoloLens augmented reality device to ensure fabrication accuracy. All the mating faces between the diagrid nodes and circular hollow section braces were machined to ensure that dimensional and geometrical tolerances were achieved.

The diagrid A frames were assembled on site and hinged into position, achieved by two crews working simultaneously. This created a safer working environment and helped speed up the program, delivering excellent cost savings.

Our outstanding work on this project awarded MJH the 2018 SCNZ Excellence in Steel Award Overall Supreme Winner and the Over $3m category awards. The judges voted unanimously and applauded the project’s outstanding execution and noted it is one of the best projects they’ve seen for a long time.

Video showcasing the construction process of 20 Customhouse Quay - click here