Domestic wood preservation - Remedial treatments in Australia
J Beesley, H Greaves
Domestic construction in Australia relies heavily upon timber. Because of availability, local conditions and building practices, the timbers and other materials employed vary considerably between the States. In recent years, the timber floor has given way to 'raft construction' (concrete slab-on-ground). Not surprisingly, there is a tendency in each State to use local timbers for building. Some 30-odd native species have been regularly milled for building purposes and, if plantation-grown Pinus radiata may be counted as a 'native' species, the timbers span a very wide range of properties. Species include the dense, strong, durable eucalypts (e.g. Eucalyptus sideroxylon, Eucalyptus microcorys, Eucalyptus maculata) through the lighter, less durable species of that genus (Eucalyptus pilularis, Eucalyptus grandis) to the 'ash group' (Eucalyptus obliqua, Eucalyptus regnans etc). In building, particularly for flooring, substantial quantitites of native conifers have been used. Notable amongst these are Agathis palmerstonii, Araucaria cunninghamii and Callitris spp. which are common in Queensland and New South Wales. In Tasmania, Huon pine (Dacrydium franklinii) makes a superb flooring. Between the wars, common imported timbers for building purposes in the southern States were Baltic pine (Pinus sylvestris, Picea abies) for linings, sheathing and flooring; Douglas fir (Pseudotsuga menziesii) for structural purposes and framing; redwood (Sequoia sempervirens) and western red cedar (Thuja plicata) for joinery and some linings, and finishing timbers. In the post-war years, there has been a notable rise in the importation of Malaysian timbers and timbers from the Pacific region, particularly the merantis (Shorea spp.). Australia spans a wide range of climatic environments, from the humid tropics in the north to the wet temperature regions of Tasmania in the south; from the treeless highlands in the Australian Alps to the waterless deserts of the interior. Within each of these regions timber in service is at risk from fungal decay or the attack of wood-eating insects. In the humid tropical regions the hazard from fungi is generally much higher than in the dry interior. Throughout the continent subterranean termites are a major hazard with few areas, apart from Tasmania, being free from them. Equally ubiquitous is the hazard from Lyctus and related powderpost borers with the Anobiid borers as an added hazard in those regions where climatic conditions do not limit their reproduction.