A research project, Wood and Wood-Hybrid Midrise Buildings, was undertaken to develop information to be used as the basis for alternative/acceptable solutions for mid-rise construction using wood structural elements. The effectiveness of the encapsulation approach in limiting the involvement of wood structural materials in fires was demonstrated in this research project through bench-, intermediate- and full-scale fire experiments. These results for encapsulated lightweight wood-frame (LWF) systems and encapsulated cross-laminated timber (CLT) systems are documented in a series of reports [3, 4, 5, 6].
In addition to developing the encapsulation approach for protecting the wood structural materials to meet the above code intent, research was undertaken to examine standard fire resistance of encapsulated wood structural assemblies for use in mid-rise wood/timber buildings. One of the major differences between structural LWF assemblies used in mid-rise wood buildings (5-6 storeys) and low-rise wood buildings (= 4 stories) is the wall assemblies for the lower storeys. For mid-rise wood buildings, loadbearing wall assemblies on the lower storeys have to be designed to resist higher axial loads due to the self-weight of the upper storeys, which often result in the need for larger-size stud members and/or a greater number of studs, and higher lateral loads in case of seismic events or wind loads, which often requires the use of wood shear panels within the wall assembly. These wall assemblies very often will need to meet standard fire resistance requirements, and therefore, information regarding their standard fire-resistance ratings should be developed. This report documents the results of fullscale furnace tests conducted to develop standard fire-resistance ratings of encapsulated LWF assemblies for use in mid-rise applications.