Now Available – Structural Commentaries (User’s Guide – NBC 2020: Part 4 of Division B)

The Structural Commentaries User’s Guide – NBC 2020: Part 4 of Division B is now available. This guide is designed to help Code users understand the design provisions in Part 4 of Division B of the National Building Code of Canada (NBC) 2020.

It provides information and suggested approaches to certain design questions related to structural sufficiency such as limit states design, snow, rain, and wind loads, and design for seismic effects.

This new edition reflects technical changes incorporated into the NBC 2020, covering topics such as:

1. Importance Categories, including post-disaster buildings.
2. Loads and load combinations for serviceability limit states
3. Tributary areas and live load reduction factors for slabs.
4. Snow loads on roofs with solar panels, drift loads for canopies and small roofs adjacent to tall buildings, and wind loads on parapets and attached canopies.

Commentary J has been comprehensively updated to align with the changes to NBC 2020’s seismic design provisions. Key updates include information on:

1. Canada’s 6^th Generation Seismic Hazard Model (CanadaSHM6).
2. The new approach to seismic hazard calculation, including the use of site designation.
3. The use of the NBC 2020 Seismic Hazard Tool.
4. The application of the new Seismic Categories.
5. The application of provisions for sloped column irregularity and for buildings with gravity-induced lateral demand.

Additionally, this edition introduces Commentary M, which addresses large farm buildings, including bins and silos.

The Structural Commentaries are a resource for designers, regulators, and builders in the construction industry. The guide is available for free, in electronic format, through the National Research Council of Canada’s (NRC’s) Publications Archive, and for purchase, in printed format, from the NRC’s Virtual Store.