If an exit through a lobby is required to meet almost all the requirements of an exit… are mechanical duct penetrations permitted? And if not how are the HVAC systems typically designed?
[/et_pb_text][/et_pb_column] [/et_pb_row] [/et_pb_section]I am dealing with a system that is used to protect storage tanks at one of our industrial facilities, this system is an outdoor deluge
NBC 2015 Div B-9.8.9.5. Treads 1) Stair treads of lumber, plywood or O-2 grade OSB within dwelling units shall be not less than 25 mm
My question is: Is there ever a time that access needs to be provided around an entire building?
Disclaimer:
Kilo Lima Community (Blog and Forum) is a platform to share ideas, ask questions and to foster discussion. The perspectives and opinions expressed in blog posts and the daily forum are those of the individual commentator and/or contributor and may not reflect the opinions and view of other readers, authors, or Kilo Lima. The information in this community is intended for educational and thought provoking purposes only and must not be construed as advice. We encourage everyone requiring code advice to consult with a building or fire code expert or their local AHJ.
Kilo Lima Code is on a mission to demystify the Canadian Construction Codes so you can keep doing great work with faster access to better resources.
Subscribe to know when new posts, tools, and courses are released.
© Copyright 2020 Kilo Lima Code | Website Design by Toro Creative Co.
2 Responses
This is a question that I find the answer really varies depending on who you ask.
Article 3.4.4.2. seems fairly clear that all requirements of exits still need to be met unless specifically relaxed, and duct penetrations are not permitted per 3.4.4.4.(1) Integrity of Exits.
Another thing to consider is the new requirement in the latest versions of the codes that introduces locations for combination smoke/fire dampers in ducts or air transfer openings where a higher level of occupant safety is required (public corridors, extended egress locations, assembly, care, treatment, detention, residential, and locations where ‘protect in place’ may be required.
If duct penetrations were permitted through an exit through a lobby, it would seem that this would also be a location where smoke/fire dampers should be provided, however it is not a listed location in Sentence 3.1.8.7.(2).
… and then you might have read Article 6.9.2.4. that says ‘where ducts penetrate fire separations separating exits from the remainder of the building, they shall be in accordance with Article 3.4.4.4.’ and wondered if ducts weren’t a permitted penetration in an exit… why would this be in the code?
Curious if anyone else has gone down this rabbit hole and what they’ve found!
In my limited experience the HVAC system for most lobbies used as an exit is usually a stand-alone unit with fresh air admitted from the exterior, therefore not requiring any duct penetrations from elsewhere in the building. Non-combustible hot water heating lines (if provided) would be permitted to penetrate as they are serving the exit. Also brings to mind the question of services located above the ceiling. Unless it’s a rated membrane ceiling (another can of worms on its own), no services permitted above the ceiling. Where something has been missed late in the game, or can’t be re-routed a horizontal shaft of rated construction is a possible solution.