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Non-rated corridor in partially sprinklered building

Question asked by m.nelson. on Jul 28, 2019
Latest reply on Jul 29, 2019 by m.nelson.

I’m working on an alteration / reconstruction of an existing building:


-Two story building

-Type 1A construction, 3-hour rated structure and floor assemblies.

-Existing and planned uses: Higher Ed B-Use Group


The existing building does not have a sprinkler system.

Proposed work is limited to a second floor renovation.

Planned work includes a new sprinkler system, that while sized to serve the whole building, will only be installed at the second floor / area of work, with first floor sprinkler system being installed at a future date.


Is there a basis for permitting first floor corridor enclosures to remain while second floor corridor enclosure is non-rated and protected by the new sprinkler system?


While the code (1020.1) does not explicitly permit this condition, I believe that the intent of the code is met. Occupants of the first floor corridor are protected by rated enclosures and 3-hour separation from occupied space above; occupants of the second floor are protected by the fire suppression system and 3-hour rated assembly below.


510.2 Gives credence to a 3-hour rated floor assembly having significance in the building code as a means of defining separate buildings when paired with a sprinkler system. While a sprinkler system below is not present, the floor assembly significantly elevates safety and separation between the floors.


Thoughts are appreciated.