Timber Monogamy

Entrant: 
Gregory Mann and Andrew Barrie Lab

Category: 
04. Exterior Structures & Landscaping Design Award

Photographed by: 
Gregory Mann, Sam Hartnett

Key team members: 
Andrew Barrie, Gregory Mann

This project acts as a landscape marker and rest structure at the top of a network of mountain bike trails. 

The project had a tiny budget—$10,000 for design, materials, fabrication, transport, and installation—and needed to be buildable by unskilled labour. Another requirement was the use of Cypress Lusitanica provided by Summerhill Timbers Ltd; this structure was built from trees grown in the forest where it now stands.

Staff and students at a New Zealand university have in recent years developed a series of timber structures, each effectively a full-scale prototype for evolving sequence of precision timber-to-timber jointing techniques. Cypress Lusitanica is lightweight, durable, and strong but can be unstable, particularly when machined into irregular shapes. This natural behaviour of the timber—warping, twisting, shrinking—makes precision difficult to achieve. This project sought to combine the use of this unstable timber with precision machining. In particular, it updated an ancient wedged joint technique to introduce tolerance and seamlessly absorb inaccuracies or deformation in the machined timber elements. 

Seeking to crystalise the technical challenge, the design eschewed completely the use of metal fixings and sought timber ‘monogamy’; it employs timber wedges exclusively—no metal at all was used in the above-ground structure. Hundreds of slender wedges and bowties were used to join the structural elements—produced on a basic CNC machine—all configured so that the structure’s natural flexing encourages the wedges to tighten.

Various design decisions simplified the construction. The structure is three squares in plan, each square made up of two identical ‘fan’ panels, each of which is symmetrical. This created a very high degree of repetition and mirroring in the elements: just four different rafters and eight different purlins, which greatly simplified and accelerated the fabrication. The structure’s geometry is simply conceived but beguiling to experience.

The series of design-and-build projects of which this structure is a part draws on New Zealand’s history of building in timber. The result is slender, lightweight, sustainable structures that point the way to new modes of timber construction. Responding to climate change through low-carbon architecture is an urgent challenge. However, other developed economies are large and very much interlinked. They can take advantage of materials and technologies and skills from across a wide area—a tree can be cut in one country, milled in a second country, and inserted into a building in a third country. 

By contrast, ours is a small nation located far from even our nearest neighbours. Our people may be able to move relatively freely, but not so building materials—we must rely mostly on materials produced locally. Our constraint is that of a modest economy—we must find ways of doing things ourselves, within our small market, and with our available technology. If we want to innovate, we might do it by making difficult things simple rather than creating more complexity. 

Rather than seeking ever more sophisticated technology, this project seeks to find new potential in an older, simpler, and readily achievable way of doing things.