Important Changes to the NBC 2020: Safety Glazing
Julia Dalphy, Technical Advisor, Codes Canada
Video chapters
Video transcript
Introduction
Hi, my name is Julia Dalphy and I am a Technical Advisor supporting the Canadian Board for Harmonized Construction Codes – also referred to as the CBHCC.
This committee is the federal-provincial-territorial body responsible for developing and maintaining the National Model Codes in Canada.
I am a member of the Codes Canada team at the National Research Council of Canada.
Codes Canada acts as the secretariat to the CBHCC, providing administrative, technical and policy support, including publishing the National Model Codes.
To learn more about code changes and provisions in the National Model Codes, or about Canada’s national model code development system, please visit the CBHCC’s website.
This presentation is part of a video series led by the CBHCC on the key technical changes incorporated in the 2020 editions of the National Model Codes.
This presentation will focus on important changes related to safety glazing in the National Building Code of Canada 2020.
History
The term "safety glass" used in the National Building Code of Canada (NBC) 2015 is not consistent with the terminology used by the glazing industry. This inconsistency could lead to confusion or to misinterpretation of the Code, resulting in the use of wrong products and potentially some fire and safety risks. Replacing the term "safety glass" with "safety glazing" will more accurately describe the material used in building assemblies. This change also harmonized the NBC terminology with the title of the 2017 edition of CAN/CGSB-12.1, "Safety Glazing," and with the industry terminology.
"Wired glass" and the referenced standard remained in the NBC. As such, you will see two terms used in the NBC 2020: “safety glazing” and “wired glass.”
The problem
Wired glass is sometimes used by designers when introducing glazing into doors and windows, particularly in fire separations. The problem is that a number of documented severe injuries have resulted from human impact with wired glass in windows and doors, mostly occurring in schools. The injuries typically resulted from tripping and falling into the glass, misjudging the height of push-type door hardware and consequently impacting hands and arms with the glass or foot contact with glass adjacent to a walking surface.
Due to the characteristics of traditional uncoated wired glass, a hand or arm can become trapped within the glazing assembly, resulting in serious injury when the person tries to remove their limb from the broken glass.
The solution
To mitigate the risk posed by contact with wired glass, measures were introduced in the 2020 edition of the NBC to limit both the probability that a person would come into contact with wired glass and that a person would experience a serious injury in the incident. The requirements are limited to assembly occupancies, where data supported the change.
Two measures are introduced to limit the probability and consequences of human impact:
- The first measure is to limit the probability: restrict the use of traditional wired glass in locations where human impact may reasonably be expected in assembly occupancies. (The sketch shows the bottom edge of glazing at a minimum of 1 525 mm above walking surface or is small enough that a 75 mm sphere cannot pass through.) In addition, introduce a standoff distance between the glazing and the adjacent walking surface to similarly lessen the probability of human impact with the glass. (Glazing is more than 915 mm from the walking surface as shown on the slide.)
- The second measure is to limit the consequence: In areas reasonably expected to be exposed to inadvertent human impact in assembly occupancies such as schools, glazing is still allowed in doors and windows. However, in these areas, the glazing will need to meet the requirements of a standard: CAN/CGSB-12.1-2017, “Safety Glazing.”
Although this change does not look as a reduction of the number of incidents between a person and glass, the potential injuries resulting from the glass panels breaking are likely to be reduced in severity.
What is next?
There was a lot of support for those changes. However, it was suggested that the restriction of wired glass be expanded to other occupancies. The 2020 changes were developed based on available data. As such, further changes to other occupancies could be proposed in the future should data become available.
There is still outstanding work to do. For example, looking at loading on glass guards, terminology and reviewing other standards.
Conclusion
This concludes the presentation about important changes related to safety glazing in the National Building Code of Canada 2020.
How to get involved
To participate in the code development process, visit the CBHCC’s website to find information about upcoming events and meetings, to submit a code change request, to comment on proposed changes during an open public review, or to volunteer to participate on a code development committee.
How to access the Codes
The National Model Codes are published by the National Research Council of Canada.
Visit Codes Canada's publications web page on the NRC’s website to purchase a paper copy of the Codes or to access them in free electronic format.
Thank you.