WHAT HAPPENS WHEN...

[Nicole Brooks]

This is a general question, so I'm just providing a fictitious scenario. Original building is a 21,000 sf single story, sprinklered warehouse building (S-1 occupancy) (type II construction) with a 7000 sf enclosed mezzanine (business occupancy) which has two enclosed exit access stairs that lead directly outside (stair shafts not rated). What happens when somewhere along the line, the owner decides they want to subdivide that warehouse into two spaces (10,500 sf ea), by installing a full height 8" cmu wall to underside of deck. The mezzanine is fully above one of the 10.5K sf spaces. Does the mezzanine now need to be considered a second story and do the stair shafts now need to be rated? I've looked at IEBC, 802.2.1 Existing vertical openings, but they don't address mixed occupancies and I can't find anywhere in the code whether mezzanines are no longer mezzanines if the areas in which they are associated with have decreased (IBC 505.2.1 Area limitations) after the fact. What do you all think?

 

[Mr. Inspector]

usually, the stairway does not need to be enclosed for a two-story building.

 

[Yankee Chronicler]

This is a general question, so I'm just providing a fictitious scenario. Original building is a 21,000 sf single story, sprinklered warehouse building (S-1 occupancy) (type II construction) with a 7000 sf enclosed mezzanine (business occupancy) which has two enclosed exit access stairs that lead directly outside (stair shafts not rated). What happens when somewhere along the line, the owner decides they want to subdivide that warehouse into two spaces (10,500 sf ea), by installing a full height 8" cmu wall to underside of deck. The mezzanine is fully above one of the 10.5K sf spaces. Does the mezzanine now need to be considered a second story and do the stair shafts now need to be rated? I've looked at IEBC, 802.2.1 Existing vertical openings, but they don't address mixed occupancies and I can't find anywhere in the code whether mezzanines are no longer mezzanines if the areas in which they are associated with have decreased (IBC 505.2.1 Area limitations) after the fact. What do you all think?

The definition of "mezzanine":

[BG] MEZZANINE. An intermediate level or levels
between the floor and ceiling of any story and in accordance
with Section 505.

IBC 505:

505.2 Mezzanines. A mezzanine or mezzanines in compliance
with Section 505.2 shall be considered a portion of the
story below. Such mezzanines shall not contribute to either
the building area or number of stories as regulated by
Section 503.1. The area of the mezzanine shall be included in
determining the fire area. The clear height above and below
the mezzanine floor construction shall be not less than 7 feet
(2134 mm).

505.2.1 Area limitation. The aggregate area of a mezzanine
or mezzanines within a room shall be not greater than
one-third of the floor area of that room or space in which
they are located. The enclosed portion of a room shall not
be included in a determination of the floor area of the
room in which the mezzanine is located. In determining
the allowable mezzanine area, the area of the mezzanine
shall not be included in the floor area of the room.

Seems pretty clear to me. If you reduce the size of the room or space within which the mezzanine is located to where the mezzaine occupies more than one-third of the floor area of that room or space -- it's no longer a mezzanine.

 

[Yankee Chronicler]

usually, the stairway does not need to be enclosed for a two-story building.

Exit stairs in 2-story buildings ALWAYS have to be enclosed -- unless the exit access travel distance from the most remote point on the upper story to an exit door on the lower story can be achieved including travel down the stair. In such cases, the stairs are not exits, they are exit access stairs.

 

[Nicole Brooks]

The definition of "mezzanine":



IBC 505:



Seems pretty clear to me. If you reduce the size of the room or space within which the mezzanine is located to where the mezzaine occupies more than one-third of the floor area of that room or space -- it's no longer a mezzanine.

Thanks, that was my conclusion too, i just wanted to see if anyone else had a different opinion.