Interpretation #9456
Published November 06, 2025
Original Request
- Code Version
- 2023
- Code
- MECHANIC
- Code Description
- Chapter
- 6
- Section
- 601.2
- Topic
- Air movement in exit corridors
Question
In a Building with NO Fire rated walls in corridors: Can a fully ducted (SA/RA/OA) AHU system serve the corridor and some adjacent offices within the same system? If there is NO air transfer between spaces. does this comply with FBC-M-601.2?
Answer Published 10/31/2025 at 10:34 AM
In response to the question as asked and the information provided, the answer is yes. A single air handler, if so designed, can serve the corridor and some adjacent offices within the same system in a business occupancy as proposed in this question. Please see the following commentary for additional information regarding systems in corridors, which may not apply to this specific instance as worded.
Commentary
Please note the following:
1. FBC-M Section 601.2 establishes limitations on the utilization of corridors (whether fire-rated or not) as elements within an air distribution system. This provision is a critical concern for life safety. Allowing corridors to serve part of an air distribution system significantly elevates the potential for a required means of egress to become a conduit for combustion byproducts. The code aims to prevent the compromise of escape routes, which are essential for occupant evacuation during an emergency.
2. All openings that penetrate assemblies that are fire-resistance rated must be provided with opening protectives as prescribed by the code or otherwise exempted.
3.Transfer grilles and transoms that convey air between adjacent rooms and spaces to or from the corridors are not allowed (with limited exceptions).
4. FBC-M Section 607.5.4 Corridors/smoke barriers specifically addresses when additional protection is required to prevent smoke from being introduced into corridors.