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With increasing timber production from New Zealand's forests, there are enormous opportunities for more use of timber as a structural and finishing material. Andy Buchanan considers who decides which materials to use in new buildings.

Timber can be used for innovative and prestigious buildings, ranging from houses and apartments to large commercial and recreational buildings, as well as bridges and industrial structures, for the local market and numerous export markets.

Timber use benefits the Government and the timber industry. It adds value to a sustainable and renewable New Zealand resource, creates employment opportunities in cities and regions, and reduces fossil fuel use, to assist compliance with the Kyoto Protocol. It demonstrates the capabilities of New Zealand timber products and pre-fabricated buildings, and develops export markets for New Zealand design expertise.

If it is desirable to encourage more use of timber as a structural or non-structural material, we need to determine who decides which materials to use.

The answer is not simple because there are so many players involved in the building process.

In a traditional building contract, the prospective owner of the building determines the needs of the future occupier, goes to the bank to borrow money, and engages an architect. The architect creates a design to meet the owner's needs, in consultation with the structural engineer and other experts. The completed drawings are used by the quantity surveyor who makes a cost estimate and advises on possible savings.

The drawings, specifications and schedule of quantities are put out to open tender, and the successful building contractor is awarded a contract for construction. The local council is involved in issuing a building consent and monitoring construction. The project is built with the assistance of the project manager. Non-structural uses in fittings and furnishings will be specified by the architect or interior designer.

All of the players in this system may be involved in selecting structural and finishing materials, at different stages of the project.

There are many variations on the traditional approach described above. For example, the contractor may be the owner acting as a developer, with no occupier in mind; or the contractor may engage the architect and structural engineer to design different parts at different times. For industrial buildings or bridges there may be no architect involved. Sometimes the project manager is appointed first, and engages the consultants and the contractor, managing the entire project on behalf of the owner. In some of the new contractual arrangements all parties work together and share both the risks and the potential profits of the project.

Material selection decisions will be made at different times by different players, often in consultation, and based on many factors:

Different aspects will have more significance at different times. For example, some players may be reluctant to use timber following recent problems relating to weathertightness and wood quality. Education and promotion are needed if future decisions are to be based on science rather than on perception.

The construction industry is a major New Zealand industry with strong traditions, healthy competition and well-established procedures. Changes occur slowly unless there are strong incentives. Most buildings are constructed with borrowed money; so lending institutions and the insurance industry also have to be comfortable before significant changes occur.

Structural engineers are key players, because regardless of what the owner or builder or architect wants, a building consent will not be granted unless the structural engineer can demonstrate that the structure and structural materials meet the requirements of the New Zealand Building Code. Consulting structural engineers work in a very competitive business environment, so they cannot explore new ideas unless commissioned to do so by their clients.

The owners are key players because they pay the bills, and can instruct other players. Owners or investors without a special commitment to timber have no incentive to build in it unless there are demonstrated benefits, especially in cost, appearance and functionality. Benefits can be demonstrated through education and positive case studies. Any change in building materials or methods will only become viable or popular if a significant number of successful applications in the marketplace give others confidence to follow the leaders.

The timber industry can provide such leadership. It is no surprise that several very large timber buildings have been built by timber industry players for their own storage, processing or office facilities; as owners, they can make these decisions at the very start of the design process. There is nothing to stop the industry from constructing more timber buildings, to act as case studies and examples for the construction industry to follow. The owners could also save money by providing some of their own materials at cost.

The Government, through the Ministry of Agriculture and Forestry, has recently provided funding for the promotion of timber in buildings. University education in structural timber engineering is already making an impact.

As the owner of many major capital developments, the Government is in a unique position to influence material selection. It would be politically difficult for government to require that more timber be used in new buildings, but it would be easy to specify that a timber alternative be considered for all new government funded buildings. For a very small increase in design fees, architects and structural engineers would be enthusiastic about creating a timber design for comparison with more conventional materials in significant projects. There are several benefits to this approach:

The comparative cost of timber and other materials would become apparent over a wide range of projects.
The cost of the extra design time would be small compared with potential savings from more competitive design and construction practices.
The results of such comparisons would establish the strengths and weaknesses of timber solutions, and areas for necessary research.
Public money would not be wasted constructing timber buildings unless they have been shown to be cost effective.
Designers would become familiar with working in timber, even if some of their timber designs are not built in the first instance.

Some building owners already engage designers to compare alternative structures in steel and concrete, for example, in multi-storey building developments, so this approach is already accepted in the building industry.

Such a government policy need not apply immediately to all buildings, but might initially apply to educational buildings,for example, then progressively to commercial, industrial and other buildings in the government portfolio. Industry organisations Opportunities for the use of timber in buildings are limited by the lack of a single, focussed organisation encouraging research into, and promotion and development of timber as a building material.

All sectors of the construction industry obtain confidence from research into building performance issues such as wind, fire and earthquake resistance, noise control, thermal behaviour and durability. If the construction industry is to embrace more use of timber, more research will be needed, as is the publication of design aids to provide confidence in timber's structural design potential, in areas such as durability, acoustics, sustainability, and thermal performance.

There is no New Zealand-wide organisation promoting the use of timber in new buildings, funding research into timber solutions, or providing the technical base which designers need. Scion (formerly Forest Research) plays a useful role in researching the quality of timber and wood products, supporting building code developments, and testing new assemblies and products. University researchers undertake similar activities. The Building Research Association of New Zealand is involved in assessing the strength and safety of houses and other timber buildings, but cannot promote timber as it maintains a material-neutral position. The Timber Industry Federation publishes the Timber Design Guide, a useful reference document. The New Zealand Timber Design Society is a group of enthusiasts who make a large impact for their small numbers and publish the New Zealand Timber Design Journal.

The combined efforts of all these groups, however, do not compare well with those of the organisations representing competing materials. Major structural materials such as steel and concrete have organisations that support research, technical advice and promotional activities. The effectiveness of new organisations including the Wood Processors Association and the Wood Council (WoodCo) will be followed with interest.

Three steps would encourage a significant increase in timber use in new buildings:

The implementation of one or more of these initiatives could significantly increase the use of timber and other wood products in New Zealand buildings.

Professor Andy Buchanan FIPENZ is Chair of Timber Design at the Department of Civil Engineering, University of Canterbury.