Preservation of eucalypt paling fences,a test of sub-standard treatments

Abstract

The traditional hardwood paling fence in Australia is installed untreated. Treatment attempts fall short of Australian Standard requirements due to limited penetration in heartwood. Nevertheless, evidence is presented that sub-standard treatment of Eucalyptus regnans and E. obliqua fencing components with either copper-chromium-arsenic or pigment emulsified creosote is beneficial to above-ground (H3) components. Palings and rails H3 exposed at Clayton near Melbourne were mostly without decay after 13·5 years. However, the top ends of chromated copper arsenate-treated posts sometimes had decay, and tops sloped for increased water-shedding did not reduce this damage. Treatment benefit was less clear for in-ground (H4) sawn fence posts. Treated posts were usually in worse condition against decay than untreated naturally durable E. camaldulensis posts after 7·5 years in an accelerated field simulator and 13·5 years at Clayton. The reverse was true after 13·5 years at Walpeup, where the main hazard was from termites.