Evaluation of timber floor systems for fire resistance and other performance requirements (2010)
AuthorsGrant, Gordanshow all
Timber is a traditional building material used for floor construction in historic buildings and is widely used today in domestic and residential construction. There is increased interest in timber for long span floor systems in commercial and multi-storey residential applications. A major reason for this interest is timbers high strength-to-weight ratio, and when used in floors, can lead to significantly lighter buildings. These resulting weight savings allow for smaller foundations and less lateral load applied to seismic-resisting structural systems. New timber and timber-concrete composite floor systems have emerged to provide increased span lengths. These longer span timber floors are typically achieved with deep solid timber joists of laminated veneer lumber or glulam, solid timber laminated deck plates and timberconcrete composite floor systems. There are several engineered timber floor joist and timber floor truss products already available in Australasia. New floor systems recently introduced into the market include Potius stressed-skin floors and Flexus floor, both of which are prefabricated into floor panels off site. The timber-concrete composite floor system utilises the compressive strength of concrete and the tensile strength of timber. The composite concrete topping adds weight to the floor system, however this is offset by structural, fire and acoustic benefits. Currently there is ongoing study of timber-concrete composite floor systems at the University of Canterbury in Christchurch, and stressed-skin floor systems at the University of Technology in Sydney, so that these longer span floor systems can be used for building design in the near future. Gypsum board ceilings are typically installed beneath timber floor systems to provide an enclosed space for distribution of building services behind a visibly uniform finish. A gypsum board ceiling can also provide fire resistance and acoustic performance and the information for these aspects is readily available. Alternatively, some floor systems allow exposed timber joists or timber surfaces. In these situations, fire resistance and acoustic performance are specifically designed.