An iconic venue reborn

A seismic assessment saw Wellington’s beloved St James Theatre deemed earthquake prone in 2015. We were engaged as project managers and engineers for one of our most complex heritage building strengthening projects ever.

A deep retrofit of a Category One heritage building was always going to be a voyage into the unknown – but an inferior strengthening job in the 1990s meant that the more we found the worse it got. One particularly challenging discovery was finding the building had been attached to a neighbouring property, with concrete poured in the narrow ‘seismic gap’ needed to allow buildings to flex safely in a shake. This took months to chip out by hand, but it had to be done to make the new structure work as designed.

The heritage listing also meant preserving the building’s fabric, where possible. The main entrance’s heritage floor tiles were disassembled on their grout lines, numbered, taken off site and reinstalled. New concrete shear walls meant a corridor shrank by 300mm width, so the original plasterwork had to be remade to fit the scale – unnoticeable to the casual observer, but an important detail to get right. Hot works in the century old tinder-dry timber roof meant fire was a constant risk too.

Strengthening was achieved with a mix of concrete shear walls, lots of steel and six viscous dampers that allowed earthquake loads to be dissipated high in the structure, rather than requiring major works on the foundations which would have made the project economically unfeasible. 

What's more, our Computational Fluid Dynamics (CFD) modelling of the auditorium was the foundation for the new displacement ventilation system. Heat pumps now drive the air conditioning to vents under every seat in the house. Operational carbon has been slashed, and the St James Theatre’s notoriously warm auditorium is now likely one of the most comfortable heritage theatres in the world.

Practical completion was achieved on the afternoon of the first performance – just in time for our team (many of whom had been involved on the project for eight years) to have a cup of tea before welcoming the first guests back into the building.

Award

ACE Gold Award