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.