Mezzanine egress

[JPohling]

Thought I would resurrect this thread as I have a question that is somewhat related. I believe I resolved this on another project many years ago but would like some fresh thoughts/interpretations. CALIFORNIA Mixed use fully sprinklered building B/F-1/S-1 32,856 SF on ground floor. There is a B occupancy mezzanine with an area of 2,457 SF (occupant load 17) that is fully enclosed and not open to any space below. This mezzanine has 2 separated exits which per CBC 505.2.3 exception #2 allows it to be enclosed and not open to below.

The two exit stairs are open non rated stairs that terminate on the ground floor into non rated corridors that lead to exterior exits. From the most remote part of the mezzanine you can go in either direction to the 2 exit stairs and out the exterior exits in less than 150' so well under the 300' maximum exit travel distance.

Does anyone believe that one of the stairs/corridors needs to be rated all the way out to one of the exterior exits? My interpretation is that as long as we can get outside within the maximum travel distances we do not need a rated stair/corridor.

Looking back on some record drawings one of the stairs originally was rated with a rated corridor to the exterior but that has long ago been modified to being non rated. That is what is giving me some concern although I think my interpretation is correct. I welcome your thoughts......................

 

[Yankee Chronicler]

Is this enclosed mezzanine really a mezzanine?







I highlighted portions of these sections to emphasize that, whether or not enclosed, a mezzanine is al elevated level within a room or space. This doesn't change even if the mezzanine is enclosed. If you can't look at it and see that it exists IN a larger room or space, IMHO it's not a mezzanine.

If it does actually qualify as a mezzanine, Exception number 2 to 505.2.3 says a mezzanine can be enclosed if it has two or more exits or access to exits. This tells me that the stairs can be unrated exit access stairs. However, to me the fact that both of your stairs terminate into corridors rather than through the room or space in which the mezzanine is (purportedly) located raises red flags that it may not really be a mezzanine.

 

[bill1952]

FWIW I have often designed theatres with a "balcony" that meets the mezzanine requirements and the 2 means of egress are typically unenclosed stairs directly to the lobby.

 

[JPohling]

Thanks Yankee! We are trying to clean up someone else's mess from years gone by. This is an office warehouse building with the "mezzanine" situated between the B portion and the F/S portion. It is clear it is a separate roof above the B portion of the building. We do not have any building sections and the satellite view shows the roof of the warehouse area to be consistent with the "mezzanine" but framed separately. I was headed down the Mezzanine rout because it was a simple calculation to show allowable area compliance for the mixed use building. I do not really feel comfortable with the mezzanine determination either.

I was able to use the frontage increase 506.3.3 to get my allowable areas up so that we can comply as a mixed use multi story building so we will be calling this a second story and not a mezzanine. Ground floor mixed area ratio comes in at .71 so less than 1. total of both floors .76 so less than 3 for a multi floor building.

Both stairs can still remain unenclosed as we easily comply with maximum exit travel distance for both.