Kirk Roberts has subsequently gained feedback from other developments that, based on the Otago Polytechnic project, the build cost was “significantly less” than comparable projects of timber construction.

Key to the project’s efficiency was the ductile design for earthquake resilience instead of an elastic design; these are different means of dissipating the energy generated in an earthquake.

“You basically have a defined point in the building which acts like a fuse where you get rid of all of the earthquake energy at that particular point.”

While engineering this system involved much greater technical expertise, the result was cost savings on materials because of the ability to use smaller structural members than if the ductile system had not been incorporated.

CLT panels are up to 80% lighter than tilt slab concrete panels so made it faster and easier for builders and sub-trades, while the prefabrication of the CLT panels streamlined the construction programme. The use of light timber also meant smaller foundations were able to be specified.

The building’s foundation comprises concrete beams supported by 700 columns of stone rammed into the ground three to four metres deep.

“Because of the lightweight nature of the building we were able to do that option instead of deep piles because of the ground being on reclaimed land.”

Rui says a timber structure of the scale of Otago Polytechnic was a first for Kirk Roberts and, from the outset, the company’s engineers were “definitely keen to be involved.”