Nail laminated timber is a mass timber product that has been used for over a century. Also known as NLT (or Nail-Lam), this product is created from individual dimension lumber members (nominal 2×4, 2×6, 2×8, etc.), stacked on edge, and fastened with nails to create a larger structural component. It is simple to construct, uses a large volume of low-grade lumber, and is as cost competitive as other prefabricated mass timber elements.
There is an increasing interest to expand the use of this product into modern larger and taller wood buildings. With funding from BC Forestry Investment, FPInnovations’ fire group has recently undertaken research studies on fire performance of NLT assemblies that led to the recent publication of three reports. These reports showcase the latest findings with regard to fire performance of this material. This research will support designers and builders in the use of mass timber assemblies, by ensuring fire safe designs.
Evaluating Fire Performance of Nail-Laminated Timber
The general objective of this work was to generate fire resistance data for NLT assemblies to address significant gaps in technical knowledge, with the intent to demonstrate that NLT construction can meet or exceed National Building Code of Canada fire safety requirements for use in buildings of mass timber construction.
Evaluating Fire Performance of Nail-Laminated Timber: Surface Flammability
The goal of this project was to confirm that NLT, when used as a mass timber element, has a lower flame spread rating than standard thickness Spruce-Pine-Fir boards when tested individually and flatwise. The project also considered how the surface profiles, design details (such as fluting), and the direction of the assembly might influence flame spread.
Evaluating Fire Performance of Nail-Laminated Timber: Influence of Gaps
This project aimed to study how the size of gaps between NLT boards might affect charring of an assembly and its overall fire performance.
For any additional information on any of these reports, please contact Lindsay Ranger, Scientist in FPInnovations’ Building Systems group.