Extension of the Concession which Allows Timber Framed Construction in Class 2 Buildings to Include Class 3 Buildings
Timber construction in multi-residential buildings has been restricted by building regulations, often without a basis in science.
This project investigated extending the building code provisions which allow the use of fire rated lightweight timber construction in Class 2 buildings (buildings containing 2 or more sole-occupancy units each being a separate dwelling) to also include Class 3 buildings such as boarding-houses, guest houses, hostels, or the residential parts of a hotel, motel, school, aged care facicility or detention centre.
A literature review investigated the burning behaviour of timber and the self-protective char layer which is formed when timber is exposed to fire together with the protection provided by fire protective cladding such as plasterboard.
A full scale experiment compared the severity of fires in two test rooms; one built using a non-combustible fire rated steel framed system with non-combustible cavity insulation, the other built using fire rated lightweight timber construction with combustible insulation.
The results demonstrated the fires within the two compartments were comparable and that timber studs, timber joists and combustible insulation did not increase the fire severity. The report concluded that building code provisions could be extended to include Class 3 buildings without an increase in risk to life.