Performance of Gypsum-Protected CLT and NLT in Natural and Standard Fires

Two large-scale tests were conducted to evaluate the performance of CLT and NLT construction protected with two 16 mm sheets of type X gypsum board in the pre-flashover, post-flashover and cool-down phases of a severe living room fire. Since minimal or no charring was observed in the room test, additional small-scale furnace tests were performed on gypsum-protected CLT and NLT specimens using standard and simulated natural thermal exposures. The furnace tests indicate that the wood continues to char for some time at a decreasing rate during the cool-down-phase. The corresponding reduction in the load-bearing section needs to be accounted for in the assessment of the fire performance of CLT and NLT structures