AN INVESTIGATION INTO THE FIRE PROTECTION OF DOMESTIC FLOORS CONTAINING TIMBER ‘I’ JOISTS, AT SERVICE PENETRATIONS

摘要

Building Regulations’ guidance, both in the UK and internationally often requires that walls orfloors be fire resistant for a specific period of time. In some instances this is due to the load-bearingnature of the wall or floor. The guidance is not always explicit as to whether protection is required atservice penetrations in or through such load-bearing constructions. Where timber ‘I’ joists or studs areutilised in these constructions, if fire or hot gas penetrate the outer fire resisting skin of plasterboard,the slender section size of these products do not offer the same degree of sacrificial timber astraditional rectangular timber sections. Consequently it may be expected that the entire constructionwould fail sooner than one constructed of rectangular timber sections.This investigation involved a small scale fire test on a sample of floor constructed using timber ‘I’joists. The floor specification used would meet the requirements of a 30 minute fire resistant floor if itwere imperforate. The construction did however incorporate an unprotected plastic ventilation duct.This was an indicative scale modelling experiment and in no way represents a British Standard orEuropean Standard fire test.