The National Building Code and Fire Code of Canada define industrial occupancies (Group F) as “… the occupancy or use of a building or part thereof for the assembling, fabricating, manufacturing, processing, repairing or storing of goods and materials”. This occupancy classification is further divided into the following:
- Low-hazard industrial (Group F, Division 3)
- Medium-hazard industrial (Group F, Division 2), and
- High-hazard industrial (Group F, Division 1).
These divisions are determined by considering the overall fuel load supported by the occupancy on a fuel-density basis for medium and low hazard occupancies. Where not more than 50 kg/m2 or 1,200 MJ/m2 of combustible contents are present per square metre of floor area, the occupancy is classified as a low-hazard industrial occupancy. If the density of combustibles exceeds one of these thresholds, then it is a medium-hazard industrial occupancy. Additionally, where ‘sufficient’ quantities of highly flammable or explosive materials are present then the space may be classified as a Group F, Division 1, high-hazard industrial occupancy.
“if an industrial occupancy also includes the storage, handling, or use of flammable liquids then additional fuel density evaluations are required”
Occupancy classification is a critical element to establish when reviewing or designing a facility for Building Code compliance. Additionally, if an industrial occupancy also includes the storage, handling, or use of flammable liquids then additional fuel density evaluations are required. Part 4 of the Fire Code regulates flammable and combustible liquids and includes a system of categories for industrial occupancies. These different categories consider the types of liquids and the manner in which they will be used (i.e., storage, dispensing, or processing) in regulating the design of a space. One element that is important to understand is the overlap of the fuel density regulations – flammable liquids will be limited by the occupancy classification and also by the Part 4 industrial category. The two systems of classification are not necessarily directly related.
For example – consider that a Group F, Division 3, low-hazard industrial building houses a repair garage. Based on the occupancy classification and building construction, the occupancy is permitted up to 50 kg/m2 or 1,200 MJ/m2 of combustible contents over the floor area. Further, as the repair garage involves the use of flammable liquids (e.g., turpentine) in conformance with the Fire Code, up to 600 L of turpentine is permitted for incidental use. Depending on the size of the room/space, the density of fuel permitted under the Fire Code may exceed the limitations associated with the Group F, Division 3, low-hazard occupancy classification.
In the above example, the Fire Code limits the volume of fuel in the repair garage fire compartment based on the classification of the fuel and the nature of the incidental use proposed. While the Fire Code specifies that the activity must be conducted in an industrial occupancy – it does not prescribe the division for the occupancy as low, medium, or high-hazard (with limited exceptions). This is not an oversight or a gap in the Codes, but it can be a complicating element that must be evaluated when considering the overall compliance of a facility and the various industrial spaces that may be present.
What about your Municipality?
Although the Building and Fire Codes define the difference between low-hazard and medium-hazard industrial occupancies, some municipalities require a medium-hazard (Group F, Division 2) classification as a default for industrial occupancies – unless it can be demonstrated otherwise. Below are links to further information from some municipalities. Please share if you know of one that should be included in this list:
Want to Dive Deeper?
Interested in learning more? The Kilo Lima Precision Course – NFCC Part 4: General Provisions for Industrial Occupancies, provides content that elaborates on this concept. The course describes five of the many different industrial occupancy categories in the Fire Code. The concept of having multiple types of industrial spaces, with different corresponding regulations is also explored.
The industrial spaces discussed include:
- Subsection 4.2.7., Industrial Occupancies – e.g., flammable liquid warehouses
- Subsection 4.2.8., Incidental Use – e.g., repair garages
- Subsection 4.2.9., Rooms for Container Storage and Dispensing – e.g., drum storage rooms
- Section 4.9., Process Plants – e.g., manufacturing with flammable liquids, and
- Section 5.5., Laboratories – e.g., quality control environments.
The course introduces the general provisions of the Fire Code for the design of these types of spaces that involve flammable and combustible liquids and guidance on classifying these industrial categories.
8 Responses
Melinda I am wondering why you chose F3 for the repair garage? Typically these are, as per NBCC 2015 Div B A-3.1.2.1.(1), classified as F2 to recognize that both the fuel load but also the activities generally undertaken such as grinding, welding, fuel system draining create a higher level of hazard.
Thanks for your comment Kevan! That is a great catch. I think that the example could have considered a factory or workshop instead of a repair garage and the point may have been more clear. Have you encountered issues similar to those described in the post in the past?
The appendix is for explanatory purposes only and do not form part of the requirements though, therefore I believe it is not enforceable. So you would still have to go the calculation route and show that there is more than 50kg/m² of combustible content.
If you are provided with a combustible content analysis showing that there will be less than 50kg/m², could you not have a repair garage in an F3 occupancy as talked about in the article example?
While you are correct that the appendix is generally explanatory and informative in nature I think you would also find A-3.1.2.1.(1) the “most likely to be enforced” Appendix note in the NBCC.
I think the change in activity from storage to repair and the associated risks involved make the justification for F2 relatively clear and that has been consistently enforced that way throughout Alberta since 1978 in my experience.
Hi Trenton – I’m inclined to agree with you – that the appendix is explanatory, and that a detailed combustible contents review could satisfy in determining the occupancy classification per the defined terms in the Code.
While it may be common practice, I do not believe there is language to prescribed that a repair garage must be a Group F, Division 2 occupancy.
Hey Melinda!
Can you give me an idea of what 50kg/m2 would look like? Considering the amount includes the building construction itself, I would think that it plus basic furniture/contents in say a hobby/woodworking shop, would add up to that amount?
Thanks so much!
Hi Jennifer – it will really depend on the specific quantities and arrangements of combustible materials in the workshop. I don’t have a easy tool or rule-of-thumb to suggest – a project specific inventory and evaluation may be necessary to support a Group F, Division 3 classification. If you’re uncertain, a Group F, Division 2 classification is often a defendable design approach.