Australian Building Code Change - Eight-Storey Timber Buildings

Abstract

Changes introduced in the 2016 edition of the Building Code of Australia permitted residential and office buildings to be of timber-framed or massive timber construction up to 25 m in effective height as a Deemed-to-Satisfy solution for the first time; typically, eight-storeys. This approach was extended in the 2019 edition of the BCA, to all classes of buildings – including retail premises, schools, hospitals and aged-care buildings of timber-framed and massive timber construction.

Detailed fire engineering modelling and multi-scenario analyses supplemented by full-scale fire testing were undertaken as part of the BCA approval process which compared the risk-to-life achieved by fire protected timber buildings to that of similar buildings (reference cases) constructed using non-combustible forms of construction. The analysis considered factors such as the frequency of potential flashover fires, effectiveness of automatic fire sprinklers, barrier (wall, floor/ceiling) performance, enclosure heating regime, occupant behaviour and fire brigade intervention. The analysis demonstrated that structural timber building elements (wall frame, floor/ceiling, shafts) protected by specified fire-protective grade plasterboard coverings can achieve a higher level of safety than traditional non-combustible construction.