# Rated corridor in B occupancy ?



## JPohling (Jul 28, 2016)

2013 CBC, non sprinklered, Type 1 building;  I am trying to understand the relationship between Table 1015.1  and Table 1018.1.

1015.1 states that for a "B" occupancy the maximum occupant load allowed for a space with one exit is 49 occupants.  1018.1 exception #4  states "A fire resistance rating is not required for corridors in an occupancy group "B" which is a space requiring only a single means of egress complying with Section 1015.1."

Table 1018.1 States that (in a non sprinklered building) a one hour corridor rating is required if more than 30 occupants are served by the corridor.

For discussion lets say that my suite is 49 occupants or less.  But because of travel distance in excess of 75 feet I need to provide another means of egress.  So I now have a corridor that is continuous to 2 separate means of egress that lead to a rated common area corridor, but the space only requires 1 per 1015.1.  If each one of these means of egress corridors is serving half of the load, lets say 24 occupants out one door and 25 occupants out the other door does that allow me to use a non rated corridor throughout this suite area?

Tenant want all glass office fronts and non-rated corridors are the ticket,  just a little confused if my logic is accurate.

Years ago here in San Diego they actually had something they called "interior tenant corridor" and as long as every suite exit had less than 30 persons exiting into the rated common corridor the interior tenant corridor did not have to be rated and the suite could be quite large, in excess of 49 for sure.

Is this a similar concept, but now I am limited to 49 occupants in the entire suite area? 

Addition of sprinklers is not an option.


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## north star (Jul 28, 2016)

@ = @


From the `13 CBC, Part 1, Section 1.1.7.3 - Conflict:

_"When the requirement of this code conflict with the
requirement of any other part of the California Building
Building Standard,  Title 24, the most restrictive_
requirements shall prevail."


*@ = @*


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## JPohling (Jul 28, 2016)

I do not believe this is a code conflict.


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## cda (Jul 28, 2016)

My take

If you do have a corridor serves less than 30 no matter how many exits, does not have to be rated

Over that rated

I have always wonder in an emergency how you herd 24 people to this exit and 25 to the other exit.


My vote is the occupant load for that entire area is the occupant number that can use the corridor


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## JPohling (Jul 28, 2016)

CDA,  How do you see CBC 1015.1, exception #4 playing into this?


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## cda (Jul 28, 2016)

JPohling said:


> CDA,  How do you see CBC 1015.1, exception #4 playing into this?




Do you have a link or am I pulling up the wrong edition



http://codes.iccsafe.org/app/book/c...NT JULY 2015/Chapter 10 - Means of Egress.pdf


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## cda (Jul 28, 2016)

JPohling said:


> CDA,  How do you see CBC 1015.1, exception #4 playing into this?




Or do you mean 1018.1?


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## cda (Jul 28, 2016)

Just limit the occupant load to 49, unless the business will have more than that for sure


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## RLGA (Jul 29, 2016)

The code states in Table 1018.1 "Occupant load served by corridor." Based on your example, the corridor is "serving" more than 30 occupants, even though 1/2 will go in one direction and the other 1/2 in the other direction. If two separate and distinct corridors are provided and each serves less than 30, then they do not need to be rated.


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## JPohling (Jul 29, 2016)

If I bisect the suite in two with a wall there are less than 30 on each side and only need access to a single exit and that works perfectly for travel distance and all other requirements.  If I place a cross corridor door in this wall to allow the suites to interconnect how does that really effect the exiting.............. now everyone has access to a second exit which is way safer, but the corridor may serve more than 30 in an emergency so it would trigger the rated corridor.  doesnt make sense in this instance to not allow it.


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## cda (Jul 29, 2016)

JPohling said:


> If I bisect the suite in two with a wall there are less than 30 on each side and only need access to a single exit and that works perfectly for travel distance and all other requirements.  If I place a cross corridor door in this wall to allow the suites to interconnect how does that really effect the exiting.............. now everyone has access to a second exit which is way safer, but the corridor may serve more than 30 in an emergency so it would trigger the rated corridor.  doesnt make sense in this instance to not allow it.




But you are talking two different code requirements , don't mix gin and whiskey


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## JPohling (Jul 29, 2016)

Ok,, hopefully a plan will help.  The portion of the floor we are concerned about is the suite area along the top of the page with 43 occupants.   I have drawn a red line to bisect the suite area.  this would allow a non rated corridor but only a single exit from each of the suites.   I believe access to two exits is much safer and do not see the value in the rated corridor in this instance.  what are your thoughts?  A cross corridor door here acceptable to allow access to two exits if needed without triggering the rated corridor?

I would much prefer access to two exits , and obviously no internal rated corridor.


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## cda (Jul 29, 2016)

If you are talking about the entire area at the top of the "new rated corridor, actual corridor"

I would not consider that area to have a corridor.

What is the total sq ft of that entire top area ??


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## steveray (Jul 29, 2016)

Firstly...we don't have fractional people so round up your offices and everything else....or at least the total (corridors and stairs included in gross)...If you put a wall there you may be creating a dead end (on second look, not) which would also not be allowed...Also might cause a CPET issue as now you would have to get into the corridor before you would have choice of 2 (60 now on the right side? would be more than 75')and Travel distance should be measured all the way to the stair door...


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## sergoodo (Aug 17, 2016)

Usually when arriving at an interpretation that is logically less safe, something is wrong with the solution (like adding doors, reducing exits).  This is not a corridor,There are cabinets, admin areas, seating, copy space, all open...not enclosed.  This space does meet the definition and requirements of intervening "area" or "room".

keep it safe, do not incorrectly define as a corridor and add wall and a double swing door.


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## JBI (Aug 17, 2016)

The Code is a minimum standard. Why people try so hard to do less will never cease to amaze me. A one hour rated wall with rated doors is just not that much more expensive than what will be installed anyway. I doubt hollow core luan doors are in the specs, and they're probably putting GWB on the walls and ceilings (possibly drop ceilings, but even a rating there won't break the bank). 
I don't think there's a conflict between 1015.1 and 1018.1, just a misunderstanding of the application.  
Exception # 4 in 1018.1 allows up to 49, as long as the building complies with 1015.1, without a rating in the corridor...
It's an 'exception' not a 'conflict'. Not all B occupancies will meet that exception.


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## sergoodo (Aug 17, 2016)

On his diagram he drew a red line where the corridor would be split and I assume a double swing door would be added.  This is not safe and with a double swinging door; people in a panic would make for some viral youtube videos with conflicting egress decisions through this door.  If you are talking about walling off this intervening area with protected openings and no divide, then of course, changing the use of the area and creating a rated corridor, a higher level of safety would be provided.


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## Paul Sweet (Aug 19, 2016)

A one hour wall didn't used to be much more expensive than an unrated wall, until the code started adding things such as smoke seals on doors, smoke dampers, etc.


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## Bryan Jay (Dec 10, 2016)

Hello everyone,
I also agree with the above comment it seems correct that one hour wall is not that expensive as compared to an unrated wall.


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## BayPointArchitect (Dec 15, 2016)

Aside from the cost of anything, I vote for the non-rated glass hallway rather than requiring a rated corridor where there does not need to be a corridor.


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## CityKin (Dec 15, 2016)

This requirement is one of my least favorite sections of code to enforce, because:

- it can get expensive if there are lots of doors and if the ceiling must be rated.  
- often the owner wants to keep the doors open, but fire doors with closers are required.
- it marginally increases safety.  Open doors increase awareness of surroundings and awareness of emergencies.
- there are a lot of situations like the one above where it is difficult to know for sure if the rating is required.  

If anything, the 30 occupant cut-off is too low.  For example, doctor's office with exam rooms,  the corridor may be a "U" shape, and if you add a waiting room and a meeting/lunch room, a pretty small doctor's office suddenly needs rated corridors.  It's kinda ridiculous.


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## cda (Dec 15, 2016)

30 ol equals 3000 sq ft

Is that when two exits might be required


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