Class 1 hardwood species in ground contact are expected to last more than 25 years, according to Australian Standard 5604 Timber - Natural durability ratings. The Standard doesn't give a precise number since actual service life depends on factors such as rainfall, local termite activity, etc. The 'probable' service life of 25 years + could be exceeded by a significant margin. Class 1 species include ironbark, Gympie messmate, grey box, sugar gum and tallowwood. Some of these species might not be available in log form, or might have to be brought to Victoria from interstate. To broaden your range you could consider Class 2 species which have a probable in-ground service life of 15 to 25 years. Note also that logs are not likely to be fully seasoned and would be best installed during autumn/winter when they can continue to dry in situ. Unseasoned logs put out in hot sun are prone to developing splits. For guidance on using round timbers you may find our Technical Design Guide no. 47 useful. It can be downloaded here: https://www.woodsolutions.com.au/publications.Playground equipment
Answered on 27-11-2020
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