This project aims to support the construction of tall wood buildings by identifying encapsulation methods that provide adequate protection of mass timber elements; the intention is that these methods could potentially be applied to mass timber elements so that the overall assembly could achive a 2 h fire resistance rating.
Standard fire endurance tests were performed on a full-scale floor assembly and a full-scale wall assembly constructed with cross-laminated timber (CLT) as the main structural element. The full-scale floor assembly consisted of CLT panels encapsulated with fiberglass wool and a single layer of 15.9 mm thick Type X gypsum board on the exposed side and with two layers of 12.7 mm thick cement board on the unexposed side. The full-scale wall assembly was constructed from CLT panels encapsulated with two layers of 15.9 mm thick Type X gypsum board on both faces. Nine thermocouples were installed on the unexposed face of both assemblies to monitor the temperature rise throughout the test and nine deflection gauges were installed on each assembly to monitor deformations. The superimposed load applied on the floor assembly was 9.4 kN/m² and the load imposed on the wall assembly was 449 kN/m. The fire endurance period of the full-scale floor assembly was 128 minutes and that of the full-scale wall assembly 219 minutes. Both the full-scale floor assembly and the full-scale wall assembly failed structurally afterwards under the applied loading. No hose stream tests were carried out on the fullscale floor and wall assemblies.
Twenty-three (23) cross-laminated timber (CLT) panels were exposed to a standard fire at an intermediate scale. This paper discusses several encapsulation methods used to increase the fire resistance of those panels, with emphasis on encapsulation times and the impact of encapsulation on the charring rate of CLTs. The encapsulation methods used included Type X gypsum board, intumescent coating, rock fibre insulation and spray applied fire-resistant materials (SFRM). The results suggest that encapsulation methods can significantly reduce wood charring rates in addition to delaying the time at which wood elements become involved in fire.