Overview
Entrant:
Andrew Barrie Lab and Batchelor McDougal Consultants
Category:
05. Innovative Timber Manufacturing & Technology Award
Photographed by:
Sam Hartnett
Key team members:
Research, design and construction: Andrew Barrie, Greg Mann, Billy Pengelly
Structural Engineering: Cass Goodwin, Batchelor McDougal Consultants
These three projects are part of an ongoing series of research-driven structures that seek to develop new approaches to timber construction—lightweight timber structural systems fabricated from small structural elements with machined timber-to-timber joints.
Earlier structures in the series, acknowledged in previous Timber Design Awards, used engineered timber that facilitated very accurate milling. As with most digitally machined structures, they relied on very stable timbers (natural hardwoods or engineered timber) that are either expensive or not suitable for outdoor use. Lower quality timbers are problematic as the natural behaviour of the timber—warping, twisting, shrinking—makes the required precision difficult to achieve.
The step taken with these structures, therefore, was to develop technology to allow the combined use of precision machining and lower-quality, unstable timber. Specifically, we have updated an ancient wedged joint technique to introduce tolerance and seamlessly absorb inaccuracies or deformation in the machined timber elements.
We have developed ‘hack’ methodologies for efficiently fabricating such elements en masse. For the first structure this was achieved with a basic CNC machine, but required the development of digital processes for modelling elements and preparing cutting files, as well as the creation of a mounting system that allowed over-length elements to rapidly be secured in the milling machine, accurately milled, and removed for assembly.
This technology is both expensive and relatively uncommon in New Zealand, so the later structures in this series sought to develop techniques that required only readily available handheld tools. This involved simple jigs, quickly and cheaply laser-cut from 6mm MDF. Tabs and slots allow these to be quickly assembled and then used with the handheld routers every carpenter has in their toolbox. Changeable panels on the jigs mean each can be used to produce the range of cuts needed for the project.
Each structure is a full-scale prototype testing our evolving fabrication research. Built with student labour, each project had only a tiny budget: $10,000 for design, materials, fabrication, transport, and installation. The timber was provided by Summerhill Timbers Ltd; the structures were built from trees grown in the forest where they now stands.
One structure acts as gathering place at the top of key mountain bike trails in the recreational park. It eschews completely the use of metal fixings and seeks timber ‘monogamy’. It employs timber wedges and bowties exclusively—no metal at all was used in the above-ground structure.
The second structure marks the entrance to a network of forest walking trails. Extending the innovation, it makes use of extremely low quality timber: misshapen trunks thinned from a seven-year-old commercial stand of Eucalyptus Globoidea.
A shelter in an events garden, the third structure sought a means to accommodate greater structural demands and so incorporated rigid bracing panels into the wedged joint system.
Our goal for this overall research project is to develop techniques that expand the possibilities for timber construction, allowing the production—on site and with ordinary power tools—of joints that were previously the province of CNC machinery or Japanese temple carpenters.