You’re designing a building, or reviewing a design, and you find yourself in Subsection 3.3.6., “Design of Hazardous Areas”, of your Building Code. Now what? Compliance with the requirements of this Subsection is only the tip of the iceberg – important design requirements are also provided in the Fire Code.
This article provides an informative guide to assist you in identifying which sections of the Fire Code will also be applicable to the hazardous area you are evaluating in a building. I’ve also highlighted some design elements that I think are particularly important to be aware of when considering these types of spaces – the ‘gaps’ in the coordination of the Building and Fire Code requirements. My hope is that with this guide a designer or a reviewer will be able to identify all the prescriptive requirements (Building and Fire Code) that could have a significant impact on the layout, construction, and design of the space as early as possible in the process.
Design of Hazardous Areas
Subsection 3.3.6. of the National Building Code of Canada (NBC) prescribes fire protection requirements for buildings, or parts of buildings, that involve the storage, use, and processing of dangerous goods. The Subsection is specific to flammable and combustible liquids and other dangerous goods where the quantity exceeds the minimum exempt amounts outlined in Table 3.2.7.1. of the National Fire Code of Canada (NFC). For a quick refresher – check out this blog post that outlines the application of Table 3.2.7.1. for chemical storage spaces.
Storage of Dangerous Goods
NBC Article 3.3.6.2. applies to the storage of dangerous goods – focusing on storage rooms for oxidizers, reactive materials, and explosives.
Additional requirements for these types of spaces are identified in NFC Subsection 3.2.7. From a construction standpoint these include requirements for: fire suppression systems, smoke venting, spill control, and fire department access.
Requirement Highlight: NFC Article 3.2.7.9. can require a fire suppression system in a building that may not otherwise require sprinkler protection under the NBC. This may significantly increase the cost of construction.
Indoor Storage of Anhydrous Ammonia and Flammable, Toxic, and Oxidizing Gases
NBC Article 3.3.6.3. identifies prescriptive requirements for storage rooms for compressed gases – where required by the NFC – however, no NFC reference is included for the user to evaluate. The correlating Fire Code requirements are provided in NFC Subsection 3.2.8.
Requirement Highlight: NFC Clause 3.2.8.2.(1)(d) requires that flammable gas storage rooms be designed to prevent critical structural and mechanical damage from an internal explosion, as described in NFPA 68, “Explosion Protection by Deflagration Venting”. The provision of deflagration vents and damage limiting construction is a significant factor to consider in the design or evaluation of a storage room.
Storage and Dispensing Rooms for Flammable Liquids and Combustible Liquids
NBC Article 3.3.6.4. directs the user to NFC Subsection 4.2.9. to determine the fire-resistance rating required for a storage and dispensing room housing flammable and combustible liquids. The Article also identifies conditions that would require explosion protection design (as described in NFPA 68) – specifically where Class IA or Class IB liquids are dispensed.
Requirement Highlight: NFC Sentence 4.2.9.5.(1) requires that an explosion protection design ALSO be provided in rooms housing open container storage of Class IA or Class IB liquids or the storage of closed containers of Class IA liquids in containers that have an individual capacity in excess of 4 L. These factors must also be considered in the evaluation of a space.
Tire Storage
NBC Article 3.3.6.5. identifies a requirement for a 2 h fire separation where a tire storage area is designed to house more than 375 m3 of rubber tires. However, NFC Subsection 3.2.4. includes additional sprinkler design requirements for these types of storage areas.
Requirement Highlight: NFC Sentence 3.2.4.3. can require a fire suppression system in a building that may not otherwise require sprinkler protection under the NBC. This may significantly increase the cost of construction.
Ammonium Nitrate Storage
NBC Article 3.3.6.6. directs users to NFC Article 3.2.9.1. when dealing with the storage of ammonium nitrate. These two Articles are well coordinated, and additional building design requirements are not provided in the NFC!
Flooring Materials
NBC Article 3.3.6.7. directs users to provide floors that are constructed of impermeable materials to prevent the absorption of chemicals where dangerous goods are stored. This requirement is consistent with NFC Sentence 3.2.7.8.(1).
Requirement Highlight: NFC Sentence 3.2.7.8.(2) also prohibits combustible floors or platforms where oxidizers or organic peroxides are stored.
Process Plants
NBC Article 3.3.6.8. identifies a requirement for a 2 h fire separation for process plants. However, NFC Section 4.9. may also prescribe explosion protection, spill control, and additional water-based fire protection systems, depending on the nature of the process and chemicals used. The findings of a fire and explosion risk evaluation will determine the extent of the protection systems required for a facility, on a case-by-case basis.
Requirement Highlight: Depending on the outcome of the fire and explosion risk evaluation, NFC Sentence 4.9.4.3.(3) identifies that additional hydrants, water supplies, and hose connections (or standpipe systems) may be required in a process plant.
NBC Article 3.3.6.9. prohibits the construction of basements or covered pits in process plants involving Class I and Class II liquids. This is consistent with NFC Sentence 4.9.3.3.(1).
Stay Tuned…
I hope that this summary was informative and helpful! If you’re interested in more content that explores the overlap (or gaps!) in the requirements of the NBC and NFC – stay tuned. Feel free to leave a comment below if there is a specific topic that would be of interest.
To learn more about general provisions for industrial occupancies and concepts for code application under Part 4 of the NFCC, keep an eye out for my new precision course launching May 31st!
