This report covers the second part of a research programme undertaken by BRANZ to develop a design method for loadbearing light timber framed wall for fire resistance. The first part of this programme can be found in SR36.
Fire performance of loadbearing light timber-framed walls can be predicted within certain limitations, provided some baseline information on the performance of similar walls is available.
Four loadbearing tests were conducted to determine if there is a relationship between results generated using small-scale pilot tests and full-sized fire resistance tests. Results from previous testing programmes were analysed further to determine the relationship between time to structural failure and the applied load level.
This report proposes a design procedure whereby results from pilot fire testing can be used to establish a starting point for design of a new wall system and hence to design a prototype for a full-sized fire resistance test.
This report also describes a new procedure whereby a previously tested wall may be subjected to a greater applied load, reducing the structural resistance time to a figure closer to but still greater than the minimum fire resistance requirement. This will enable more efficient use of materials in meeting fire resistance requirements.