Whether timber would achieve a 1-hour fire rating depends on the size and density of the species of timber. Our Technical Design Guide #06, titled Timber-Framed Construction – Sacrificial Timber Construction Joint, explains how to use timber's charring properties.

Depending on the type of hardwood, H3 treatment might not be needed. A marine environment is not particularly hazardous for dense hardwoods, but care is needed in specifying fasteners since a salty atmosphere is highly corrosive to metals. Durability Class 1 hardwoods such as ironbark, spotted gum, blackbutt etc. would achieve a probable life of up to 40 years out of ground contact according to Australian Standard 5604:2022, Timber - Natural durability ratings. In fact the heartwood of such species is difficult to treat effectively.