Canada Wood Today | The Canada Wood Group

NLT Roof Structure Fire Tests Successful

Hidehiko Fumoto

By Hidehiko Fumoto

Deputy Director and Manager Technical Services, Canada Wood Japan

August 8, 2019

As part of our current market access technical development projects, COFI and the Japan 2×4 Home Builders Association are aiming to obtain the ministerial approval of floor/roof diaphragms made from dimension based Nail-Laminated Timber (NLT). On July 16th and 17th, NLT structural roof assemblies were fire tested at the horizontal furnace in the Nishinihon Test Laboratory of Japan Testing Centre for Construction Materials (JTCCM) in Yamaguchi Prefecture. Subsequent to the floor assembly tests in December 2017, this test serves as preparation work to confirm the flame behavior before the real tests for obtaining the quasi-fire resistive ministerial approvals.

In the case of roof structures, the duration of burning is 30 minutes. On July 16th, the testing was conducted for the specimen with the same specifications as that for the approval. We applied vertical loads equivalent to 65 kg/m2 (live load required by the testing protocol) + 55 kg/m2 (equivalent to Japanese roofing tiles). On July 17th, three different types of NLT roof assemblies were tested, simulating fluted and curved NLTs. All test results demonstrated the sufficient quasi-fire resistive performance; i.e.) temperatures lower than 100 – 120 degree Celsius at the depth of 30 mm from the burned surface at the elapsed time of 30 minutes, no fire penetration through the cross section, deflection of less than 303 mm and less than 13.5 mm/minute of rate of deflection. Based on these successful test results, it is scheduled to conduct the real tests (performance evaluation tests) in November 2019 at the same laboratory. This work is intended to open up market opportunities for Canadian dimension lumber in Japanese mass timber applications.