Specialty timbers penalised for radiata pines shortcomings
Specialty timber species are being severely penalised in pursuit of an acceptable strength standard for radiata pine timber.
NZFFA Press Release 16 May 2011
Radiata pine and Douglas fir comprise most of the structural timber used in buildings, but other timber species with special attributes (such as natural durability and strength) have been shut out from the building code as a result of revising
The interests of both specialty timber growers and sawmillers have been spurned by a standards committee dominated by radiata industry representatives bent on protecting pines market image and the Department of Building and Housing who have decreed that all timber in buildings is to be verified by a third party audit. The result has been the introduction of a quality control system designed for only larger sawmills processing radiata pine and Douglas fir. All other options have been removed for consumers who want to use other timber species for design solutions provided in NZS 3604 Timber Framed Buildings. No longer can people choose untreated timber such as macrocarpa for structural applications in their buildings. Growers and sawmillers who have dedicated years of hard work to produce a quality timber product have been summarily and unnecessarily dismissed from the market.
Radiata pine's strength and stiffness properties are highly variable
All the structural boards from a utilisation study of 25 year old eucalypts
Sawing and grade recovery of 25-year-oldEucalyptus fastigata, E. globoidea, E. muelleriana and E. pilularis Trevor G. Jones, Ruth M. McConnochie, Tony Shelbourne, and Charlie B. Low. New Zealand Journal of Forestry Science 40 (2010) 19-31 were found to be equivalent to SG 10 and above based on MoE values. Thus visually graded structural eucalypt could conservatively be allocated SG 10 without any further need for verification.
Studies have shown that cypresses are well known for reliable timber properties
Cypress timber does not vary muchin density between trees or within a single tree. In contrast to radiata pine, there is only a slight increase in density with distance from the pith. Cypress timber is moderately stiff and strong - almost on a par with New Zealand-grown Douglas fir, so it is suitable as a framing timber. Source: Forestry Insights , regardless of growth conditions and should be allowed as visually graded SG 6 for timber framing without further verification.
This would more than meet the requirements for building integrity behind NZS 3604:2011. Because visual defects affecting strength would be obvious in any product, a producer statement would be sufficient to assure consumers that product was fit for purpose.
The requirements for verification of timber under NZS 3622:2004 are completely unreasonable for operations producing limited volumes of specialty timbers. In addition, verification is impossible for larger structural beams thus eliminating these from structural use in New Zealand. To impose such rules is both unwarranted technically and impractical for them to implement.
Alternatives need to be provided so specialty timbers can be used for design solutions provided in NZS 3604 Timber Framed Buildings. Growers and sawmillers of New Zealand's specialty timbers should not be penalised for radiata pine's shortcomings.
Contact: Dean Satchell (09)4075525 (021)2357554
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