Wider Use Of Timber In Engineering Urged

Press, Volume CVI, Issue 31231, 1 December 1966, Page 6

Wider Use Of Timber In Engineering Urged

Misunderstanding of the durability and fire resistence of timber was one of the major reasons hindering the use of timber for engineering purposes in New Zealand. Mr R. D. Evison, a Wellington consulting engineer, told timber industry representatives in Christchurch last evening. The annual meeting of the Timber Development Association was held in Christchurch yesterday. The misunderstanding of durability was often through ignorance of modern timber treatments, Mr Evison said. Building by-laws and insurance rates often grossly un-der-rated the fire resistance of

timber, and in fact the superior fire resistance of heavy timber, compared with steel framing had been amply documented.

New Zealand had a large and vigorous timber industry. The potential for engineering use of timber was very large, and the advantages of realising this potential could be enjoyed not only by the industry but by the country as a whole. Suitable native timbers were now in limited supply, but exotic softwoods were plentiful and the supply was increasing. Factory fabricated members were becoming more widely available, and special connectors and nails were also available.

The requirements for engineering included strength, durability, economy, and uniform and identifiable quality. New Zealand-grown exotics were comparable in strength with engineering timbers in many other countries, and in appropriate grades were suitable for most engineering purposes. Suitably treated timber was more durable than the best available untreated timber: and processing costs in New Zealand tended to be high so timber was more economical in simple structures, although uncoventional designs could be expensive until builders gained experience.

New Zealand grading rules were satisfactory, with some qualifications for special work, but they were not yet sufficiently observed, particularly lon the engineering side, and (too often grade was not identified on the material.

Excellent research work was being done, notably by the Forest Research Institute of the Forest Service, but the gaps in engineering data were very large and inhibited timber engineering progress. Timber construction could reduce over-all costs, and in the present economic circumstances, which might be longlived, the wider use of timber could get more work done with available capital. As the timber industry seemed to suffer from capital restrictions more than the building industry as a whole, there were double reasons for striving for the greater use of timber. “New Zealand needs to reduce the cost of building. Beyond the high present level of costs is the future cost of obsolescence, falling on buildings and engineering works of all kinds. Bridges, large buildings, harbour works and industrial plants are seen to be demolished for this reason while still sound, representing a measure of waste. Much thought should be given to initial economics for this reason,” Mr Evison said.