The inclusion of alternative species to radiata pine, predominantly exotic species, in the building code (NZS 3602) raises questions as to whether they require preservative treatment and, if so, whether they can be adequately treated using current industry processes. Early research with boron indicated that the dip/diffusion method for green timber would give adequate preservative retention in sapwood for most species and in some cases would also penetrate heartwood. This was widely accepted by the industry as being the case for species other than radiata pine including those regarded as resistant to preservative treatment such as Douglas-fir (Pseudotsuga menziesii). Some further work was done on treatment of radiata pine (Pinus radiata) and Douglas-fir framing using boron-glycol formulations and low-pressure systems but treatment of species other than radiata pine with boron using current commercial processes has not been widely tested. This article summarises research conducted at Scion on the performance of boron preservatives applied to species other than radiata and similar plantation-grown pines.

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