Overview
Entrant:
Dunning Thornton
Category:
10. Commercial & Industrial Building Design Award
Photographed by:
Jason Mann
Key team members:
Alistair Cattanach (Structural Engineer, Dunning Thornton),
Chris Moller (Architect, CMA+U)
Sam Curtis (Architect, MacKay Curtis)
Paul James (Services Engineer, 335)
Stephen Lockyer (Project Manager, The Woolstore Group)
Glulam & LVL Timber: Techlam
CLT Timber: Red Stag
ETFE Facade: Vector Foiltec
Kai Tahi is a substantial step towards transforming Porirua’s waterfront. Reusing an industrial warehouse and dead-end service lane turning it into a 600m2 public arcade and 1700m2 food hall marketplace.
The arcade establishes a new axis, like an amphibian walking up from the sea towards the town centre and Pātaka Art Museum. A new symbol for Porirua; to re-orientate and connect the city to the sea. A meeting place on the water’s edge, that embraces a diverse range of vibrant offerings, connecting food, small local businesses, a vibrant art space and most importantly, people.
The exposed structural form gives a feeling of openness which draws people into the development. The lightness of the glulam structure is further reinforced by the transparent, lightweight ETFE roof, punctured by joyful yellow skylights, whose light pools move through the arcade with the sun. The ETFE triangles were very efficiently fixed directly to the timber structure without the need for secondary framing that would reduce the open feel.
The mezzanine spine provides additional quiet seating space, roof garden, outlook, and contains below the supporting functions for the open warehouse space including kitchens and toilets. The external area permits light down into the warehouse and provides sheltered outdoor space.
With the challenges of liquefaction at the water’s edge, timber unlocked the engineering solutions. The mezzanine is CLT, the floor is lighter than conventional alternatives which would have been too heavy to shallowly found on the crust over the potentially liquefied soils. The reduced bracing requirements mean that bracing could come from the ply lined kiosk walls. The soffit is exposed to let the timber breathe and the mezzanine edge is elegantly tapered and uses the panels’ capacity to span in both directions to give a clean and attractive appearance.
The arcade is a tied arch in cross-section: but expanded in 3D so every timber joint is constrained by an (offset) cable giving moment resistance. This diagrid form also provides longitudinal rigidity. The joints in the timber are pins, and in permanent compression, and so they can be very simple.
Use of prefabrication on the ground of the all the arcade timber and steel elements enabled time and cost savings and allowed for quick on-site assembly and erection of the arcade.
Honest materials have been used wherever possible. Timber has been left exposed with coatings only applied where needed for protection. Timber grain, laminations, and knots are visible. Similarly, all other structure and building services are exposed within the finished building.
Colourful painted elements have been carefully designed to contrast beautifully with the natural richness of the exposed timber.
You can get up close to the glulam legs, the CLT walls of the entry doors at each end of the arcade axis and the Laminated Veneer Lumber (LVL) handrails. The timber provides a softness and warmth that brings a humanity to re-use an old warehouse space. The result is a dynamic space, containing playful timber elements with a sense of lightness and a touch of joy.