Office Suite Corridor Rating

[cuyoda]

I have an office building with a suite of offices on one side of a main building corridor running north to south. There are exit stairs at either end of the main corridor. The office suite itself requires two exits, to accommodate the required 75’ common path of egress requirement and an occupant load of over 30. So the corridor inside the suite is a “U” shape beginning and ending with doors at the main north-south corridor. The building is un-sprinkled Type IIB, thus the code states that corridors need to be 1 hour rated, since they carry over 30 people. But is the U shaped corridor inside the office suite considered a corridor that needs rating just like the main building corridor?

I can’t recall ever seeing an office suite corridor that is rated, but I can’t seem to find anything in the code that talks about this type of situation. Thanks for any help.

 

[TimNY]

What is the distance to the exit?

 

[cuyoda]

What is the distance to the exit?

95' to gain access to the main building corridor from the most remote office in the suite (travel distance down the suite corridor is included in that distance). 136' from that most remote office to an enclosed exit stair.

 

[Gene Boecker]

The corridor must be rated since there are more than 30 occupants dependent on it's use to reach an exit.

This is a larger suite and the choice to create a corridor is what is causing the issue. We went through a similar discussion about this a short while back and issued a formal interpretation on corridor continuity. Although the subject was different, the basic background was the same.

http://www2.iccsafe.org/cs/committeeArea/pdf_file/BU_06_56_08.pdf

 

[cuyoda]

Excellent info. Thank you.

 

[cuyoda]

In the interpretation you sent me though, how does the occupied space not fall into the catagory of an "intervening space" (which can't be exiting through if utilizing a rated corridor)? I potentially have this condition occuring elsewhere in my building.

If I understand your response correctly, you are considering the occupied space as a continuation of the rated corridor. Thus it would be rated as well. But it sure does look to be an intervening space

 

[Builder Bob]

Does the tenant space itself serve over 30 occupants? If so, the U shaped corridor would be requried to be rated. If this U shape corridor is rated, the main corridor must be one hour rated to provide the same level of protection until the exit is reached (i.e. stairway)

 

[Gene Boecker]

cuyoda,

First - where are my manners!?

Welcome to the Forum!

Next - yes, if the corridor stops short of an exit, then the intervening room needs to be addressed. If the corridor dumps the occupants in to a foyer or lobby that's fine since it meets the exception. But the lobby/foyer needs to have the fire rating continue around it.

In the interp that I sent the link for, we battled on the application to the center space and what, if any requirements were needed. The interp committee was divided on whether or not that room also needed a rating. For simplifying the response, we chose to ignore that complication and focus only on the issue regarding the rated corridor. Since the travel; distance within the tenant space dictates that there must be two means of egress, the exception for unrated corridors in a single egress space don't apply. Therefore the tenant space corridor and the main corridor will need to be rated.

Now, all this is predicated on the fact that the building is not sprinklered throughout and subject to the provisions in Table 1018.1 which allow for the corridor to be unrated "with sprinkler system."

 

[Examiner]

If the u-shaped corridor in the suit of offices has an occupant load from the offices of 30 or more; then the u-shaped corridor requires fire rating as well as the main corridor. If the occupant load is under 30 using the U-shaped corridor then a rating is not required. This is assuming that the u-shaped corridor is exclusively for the suit of offices and is not open to the main corridor's occupant load. If people from the main corridor have access to the u-shaped corridor then all corridors would be rated. NOTE: The suite of offices and the U-shaped corridor within the suite of offices should have a floor area of less than 3,000-sf gross. (Office occupant load at 100-sf/p x 30-p = 3,000-sf)

 

[Builder Bob]

examiner... don't forget pockets of assembly - i.e. conference rooms which may drive the occupant laods up that use the corridor.