Environmental Impacts of Multi-Storey Buildings Using Different ...

- 95 -8.2 Source and Availability of TimberNew Zealand has a substantial forestry industry which ranges from the efficient growing ofspecialist plantation species through to modern harvesting techniques, to milling andtreatment, the provision of engineered timber products such as laminated veneer lumbar(LVL) and Glulam and the manufacture of timber components.Increasingly, a large range of timber products are available to offer alternative options todesigners and builders for both main structural building components and architecturalfinishes.NZ forestry – and hence the product supply chain – is dominated by Pinus radiata. Thisversatile timber offers a product range which, with little processing, can be used for thesupply of standard framing material through to lower end value-added products such asplywood and medium density fibreboard (MDF) and increasingly through more technicalmanufacturing processes to engineered components, such as LVL.P. radiata is not a naturally durable timber, often requiring treatment to extend its lifetimeand useful range of applications. An alternative to treatment is to source more naturallydurable species, such as Western Red Cedar. Also, for both technical and aesthetic reasons,other timber species may be more appropriate than P. radiata in some applications.The Warren and Mahoney report covers each timber component of the buildings and details acommercial source which could meet the demand for the quantities specified in the buildingdesigns. Where possible, timber has been sourced from a local supply.NZ supplied P. radiata was suitable for much of the structural timber, finishing and joineryincluding the following;• Columns, beams, joists, shear walls and portals.• Interior and exterior wall framing.• Internal solid walls.• Roof and parapet framing.• Ceiling tiles.• Floor.• Internal stairs.• Exterior wall cladding.The TimberPlus building proposes a P. radiata timber exterior wall cladding, ‘Shadowclad’,an engineered product supplied by Carter Holt Harvey.An interesting alternative for exterior cladding is the Flatline Board System currently underdevelopment by Australia’s Timber Development Agency (TDA)(www.timber.net.au/flatline) – this is an “open-source” system which can be utilised by anycladding manufacturer. Theoretically, therefore, it could be manufactured in NZ utilisinglocally sourced timber.The quantities of LVL required for the Timber and TimberPlus buildings are certainlyavailable for supply in NZ. Plywood, MDF and framing materials are readily available “offthe shelf”.