This study investigated the treatability of the sapwood and heartwood of sawn Eucalyptus grandis with copper-azole (CuAz) and disodium octaborate tetrahydrate (DOT) water-borne preservatives towards improving its durability for enhanced use in structural solid wood applications. The results obtained showed that, at a moisture content of 12 ± 1%, sawn E. grandis sapwood can be impregnated to a mean retention level of 4.61 kg/m3 with CuAz and 7.98 kg/m3 boric acid equivalent (b.a.e) with DOT. The highest mean retentions obtained in the heartwood were 2.10 kg/m3 and 3.52 kg/m3 b.a.e for CuAz and DOT respectively. The findings revealed high sapwood and limited heartwood permeabilities of E. grandis, thus agreeing with the South African National Standards (SANS 10005:2016) categorization of E. grandis as amenable to impregnation. This study outcome showed that obtaining suitable preservative retention levels in sawn E. grandis with considerable sapwood content is feasible. Furthermore, the study provides a basis for consideration of sawn E. grandis durability treatment with CuAz for hazard classes H3 and H4, and DOT for class H3 subject to other conditions being met such as the SANS 10005:2016 prescribed coating maintenance required for the latter treatment.

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