As code consultants, there are certain questions from clients that come up quite often. One of these is related to whether tenant separations in buildings are required to be fire-resistance rated. It appears that much of this uncertainty is related to changes in the code provisions over the years.
In many older buildings constructed under the BOCA National Building Code, you will find that 1-hour rated walls were commonly provided between different tenants within the same building. These are observed in the field as full height walls with fire doors and penetrations/joints sealed with firestopping. Why are they there? Are such tenant separations required for new construction?
Up until the 1999 BOCA National Building Code (6th Edition and earlier in Massachusetts), 1-hour rated fire partitions were required to be provided between tenants in buildings with protected construction types, regardless if the walls were bearing or not. This 1-hour rating would span all occupancy classifications and uses including office buildings. As states transitioned toward adopting the newly introduced International Building Code (IBC) beginning in 2000, these requirements changed. Under the IBC, fire-resistance rated tenant separations are no longer required outside of covered malls.
Reference: 1999 Edition of BOCA National Building Code Table 602
It is important to remember, that although most tenant separations are no longer required by current codes, existing fire-resistance ratings between tenant spaces must be sufficiently maintained if required by the code at the time of construction. Further, there may be various conditions requiring fire-resistance rated partitions/barriers between different tenants including, but not limited to, control area boundaries, occupancy separations, vertical opening protection, etc.