Canada Wood Today | The Canada Wood Group

NLT Technical Project Report Published

Hidehiko Fumoto

By Hidehiko Fumoto

Deputy Director and Manager Technical Services, Canada Wood Japan

May 26, 2020

This past year COFI/Canada Wood Japan worked with the Japan 2×4 Home Builders Association to facilitate the spread of large-scale wooden buildings using Nail-Laminated Timber (NLT) in horizontal diaphragms such as roof and floor structures. One of the goals was to confirm 1-hour quasi fire-resistive performance for floor assemblies and 30-minute quasi-fire resistive performance for roof assemblies. Regarding structural performance, the research required NLT configurations with butt joints to evaluate and compare performance versus NLT without butt joints to ensure all potential structural weaknesses are fully understood. COFI and the Japan 2×4 Home Builders Association jointly worked to conduct a series of bending tests. These were the 4-point loading bending test to 2×12 and 2×8 Canadian SPF. After collecting the data, we confirmed that our numerical modelling works accurately on the rotational rigidity at the butt joints. Those test results were compiled in a 508-page report booklet. This report has recently been completed and released and will serve as a resource for structural engineers designing NLT diaphragms.