EVstudio has designed a number of storage mezzanine projects in existing warehouses, and it is important to remember the requirements for openness set forth in the IBC.
Mezzanines must conform to the requirements for Openness in Section 505.2 of the 2009 IBC. Mezzanines need to be open and unobstructed to the room in which it is located, except for walls, columns, and posts not more than 42” high. There are several exceptions: Mezzanines are not required to be open provided that the occupant load of the enclosed area does not exceed 10. Mezzanines having two or means of egress are not required to be open if at least one of the means of egress provides direct access to an exit from the mezzanine level. Mezzanines are also not required to be open if the floor area of the enclosed space does not exceed 10 percent of the mezzanine area. In industrial facilities, mezzanines used for control equipment are permitted to be glazed on all sides. In occupancies other than Groups H and I, that are no more than two stories above grade and that are sprinklered, a mezzanine having two or more means of egress are not required to be open to the room in which it is located.