View Full Version : unlimited area buildings - mixed occupancy bldg w/ use group A-2

June 1st, 2011, 22:35
1 story type IIB 130,000+sf sprinklered bldg with mostly retail (M) proposes to change 4800sf to two restaurants (A2).
IBC 2009 jurisdiction.

507.3.1 Mixed occupancy buildings with Groups A-1 and A-2 allows this provided:

1. the new A2 spaces are separated by 2 hour fire partitions even with sprinkler system.
2. each A2 space can NOT exceed 9500 sf.
3. all required exits from each space must exit directly to the exterior; aka the 2nd exit can NOT be to an existing rear hallway (corridor) that leads to the outside(?).

correct??? comments???

could the rear exit hallway apply if it was considered a horizontal exit or a corridor?? if a corridor can it be shared between multiple spaces??

June 2nd, 2011, 07:31
If the aggregate area of the A occupancies were less than 10% of the building area, I wonder if it would be possible to allow the area and height to be based on the main occupancy per 508.3.1.2 (2006 IBC)? I'd like to know what you and other members think about this.

To answer your question directly, note the code says exits shall discharge directly to the exterior. Maybe if the corridor was built as an exit passageway?

Coug Dad
June 2nd, 2011, 09:15
10% and less than the tabular value of Table 503. No increases for sprinklers or separation.

June 2nd, 2011, 10:10
Ah, Mixed Occupancies.

Do not have the 2009 in our area. No AHJ is using it around here.

2006 IBC Section 508.3; has three ways to deal with mixed occupancy separations. You have to choose which one in most beneficial to your project.
1. Accessory occupancies: Section 508.3.1; is the 10% rule
2. Nonseparated occupancies: Section 508.3.2; is where you get the mixed occupancies to have all the whistles and bells for the entire building in trying to avoid rated separations.
3. Separated occupancies: Section 508.3.3; this is when you have to use rated separations.

The catch with your project is that the building is using the Unlimited Area Section for all the occupancies uses. The Assembly as you pointed out has to comply with the Exceptions for A-1 and A-2. Per the Exception the Assembly separation must follow Section 508.3.3.4 and area limit in Section 503.1.

Section 508.3.3.4 sends you to Table 508.3.3; I see a 1-hour separation between A, B & M for a sprinklered building.

As for Section 503.1 it is the section where the Table of the allowable area is listed. You are not allowed any area increases for the accessory occupancy.

The Assembly Exits must be to the exterior or discharge into an EXIT or EXIT Passageway that leads to the exterior.

Hope this is of some help.

Coug Dad
June 2nd, 2011, 10:36
Two approaches allowed. If the assembly space is small (<9,500 sf and <10%), you can follow the accessory use provisions and no fire resistive rated separation is required and the exits do not have to be directly to the outside. If the assembly space is larger, then the separation is required and the exits must discharge directly to the outside.

Builder Bob
June 2nd, 2011, 12:22
Be careful with accessory uses - Means of egress issues must be designed in accordance with chapter 10 for the intended uses - section 1024? Assembly may have requirements for exits that lead directly to the exterior based on projected occupant loads base dupon the use of the floor space.

June 2nd, 2011, 13:48

June 2nd, 2011, 15:08
thx u all.

just got back from the site survey.

texasbo - the rear exit spills into a exit passageway....only 1 other tenant (other door; other restaurant user) uses the corridor.

the exit passageway goes right to the outside.

the other good thing discovered is there is a "fire wall" on the one side that basically reduces the overall SF down to approx. 34700 sf. with 4800 sf total split for the 2 restaurants and the rest is 1 mercantile tenant and the exit passageway.

of course some frontage area credit is lost....but looks good to me between the sprinkler system and the exit passageway. the other restaurant is already in & operating too...they may have another door around the side to the outside in addition to the passageway door...

full sprinkler system.

thanks again for the attention.

June 2nd, 2011, 15:38
Are you sure it is a real firewall or a fire barrier? Firewalls have to remain in place upon the collapse of the building on either side.

I ask this because you mentioned unlimited building. If there are firewalls then some of the rules and comments may change.

FM William Burns
June 2nd, 2011, 15:44
Nice catch Examiner......that use to really tick me off when I was reviewing and dealing with proposals for Chapter 8 of the NFPA Life Safety Code.................terms...............sorry.... ..........carry on :)

June 2nd, 2011, 16:55

the link above shows photos of the wall from survey.

the architect's drawings for the previous up fit labelled the wall as a fire wall on his drawings.

I will ask the landlord to provide a section drawing thru the wall to further verify if indeed it is a fire wall.

thx u very much.

June 2nd, 2011, 17:20
As a Architect I can tell you that not all Architects know the difference between a fire wall and other fire rated walls (fire barrier & fire partition).

It looks to me like an area separation wall that is no longer allowed. Area separation wall was in the UBC as I recall but never in the SBC.

However, you do need to find out if it will structurally stand in place upon collapse of the building on either side. I think the roof will take the wall down.

June 2nd, 2011, 21:50
this condition could be a laterally supported loadbearing fire wall....

page 3 of pdf link


yes trying to get more info on the condition....

thx u.

June 3rd, 2011, 09:59
Is this a strip center, outdoor mall or covered mall building?

The photos down the corridor appear as if it is one of the above mentioned types of mercantile buildings.

Read the Section on Fire Walls carefully. Check to see if the vertical and horizontal abutments of the wall to the roof and exterior walls comply with the many allowed exceptions. Doing that may also determine if the fire wall complies with end terminations. Also notice the allowable max penetrations in the Code and what is actually there. One photo seems to reveal a walled up infield where a door or other opening was. It just does not look like it was to be a FIRE WALL. More like an area separation wall or maybe an occupancy separation wall (fire barrier).

Fire walls are generally straight through the building from exterior wall to exterior wall and depending on the end termination may not be required to extend beyond the exterior wall or roof line.

June 4th, 2011, 15:21

it is a strip center.


the photo down corridor separates a large supermarket (acme brand in the NE) from a TJ Maxx clothing and now the 5 guys burgers and soon to be saladworks....

yes will review the fire walls section. yes there is an area of the wall where it does appear to be CMU infilled under a lintel.

thx u for ur attention.

June 4th, 2011, 17:31
Accessory Uses are within an occupants space when you jump to Mixed and especially mixed within an unlimited by 507 not by 503 thing change

have to stay within the 507 rules

If for example Target was a seperate occupancy withing this overall the A-2 coffey or pizza shop they ususally have would be assessed as 10% of their space
to determine accessory not 10% of overall total mixed building area

June 5th, 2011, 14:54
The accessory spaces are for the main occupancy of the building; in this case M. The 10% limitation applies to the entire building area for the story in which they're located, not the individual spaces/tenants with which they're associated.

However, Architect1281 is correct, you really can't jump between Sections 507 and 508. If unlimited by 507, then the occupancies are restricted by that section and Section 507.3.1 would be applicable. With Section 508, you're restricted to Table 503 and the allowable increases; but I don't see how you can get a 130,000 sf Group M with Type IIB construction, anyway.

The situation has to be either an unlimited building per Section 507 or they used a fire wall to break the building up into smaller buildings, which, as many have pointed out, needs to be verified if it truly is a fire wall.

If Section 507 is applicable, then we are back to syarn's question regarding exits from the Group A-2s. Subparagraph 3 of Section 507.3.1 states "exit doors from Group A-1 and A-2 occupancies shall discharge directly to the exterior of the building." Note that it states "exit doors" and not just "exits." If it stated just "exits," then I would agree that an exit passageway would suffice. However, the use of "exit doors" leads me to interpret the requirement that the door that leads from the A-1/A-2 space (exit door) must go directly to an exit discharge--no exit passageway, no horizontal exit, nothing.

But, playing devil's advocate (i.e. the clever architect), one could state that a door to a corridor leading from the Group A-2 occupancies (no Group M occupancies using the corridor) is an "exit access door" and not an "exit door"; thus, when the end of the corridor is reached, the "exit door" does discharge directly to the exterior. This is a bit of a stretch, but plausible by using of the code's own terminology against itself. Therefore, if I were in a position of reviewing a project in this situation for an AHJ, I would likely allow the use of an exit passageway, since it is much more protective than a corridor.

June 6th, 2011, 10:38
EXIT. That portion of a means of egress system which is separated from other interior spaces of a building or structure by fire-resistance-rated construction and opening protectives as required to provide a protected path of egress travel between the exit access and the exit discharge. Exits include exterior exit doors at ground level, exit enclosures, exit passageways, exterior exit stairs, exterior exit ramps and horizontal exits.

COMMENTARY: Exits are the critical element of the means of egress system that the building occupants travel through to reach the exterior grade level. Exit stairways from upper and lower stories, as well as horizontal exits, must be separated from adjacent areas with fire-resistance-rated construction. The fire-resistance-rated construction serves as a barrier between the fire and the means of egress and protects the occupants while they travel through the exit. Separation by fire-resistance-rated construction is not required; however, where the exit leads directly to the exterior at the level of exit discharge (e.g., exterior door at grade). Figure 1002.1(2) illustrates three different types of exits: interior exit stairway, exterior exit stairway and exterior exit door.

My opinion: Doors that you pass through to get to the door leading into but not entering an EXIT, EXIT STAIR or EXIT PASSAGEWAY would be Exit Access Doors but the doors into the three types of possible EXITS are EXIT DOORS as well as the doors leaving the aforementioned types of EXITS to the Publicway. In the case of the Assembly addressed in this post, “to have Exit Doors that discharge directly to the outside”; I do not see an issue with using the EXIT PASSAGEWAY which is an EXIT to have their exterior exit doors discharge to the outside. Once you are in one of the types of EXITS you are protected to the exterior exit door where you discharge to the Publicway. Thus they are discharging from the EXIT as required to the outside.

June 6th, 2011, 11:35
thx u.

ron what if I call the existing wall a fire barrier that creates a "fire area" of approx. 36000 sf with 5240sf of A2 and 29450sf of mercantile?

June 6th, 2011, 12:34

I don't think the wall being a fire barrier would have any bearing on the stated requirements unless it was a fire wall. As a fire barrier it helps by compartmentalizing the construction. But you still have the requirement in Section 507.3.1, subparagraph 1, that requires the 1-hour fire barrier for occupancy separation for the A-2 occupancies, and the A-2 fire areas created by the existing wall creates fire areas that exceed the allowable areas of Table 503 per Section 507.3.1, subparagraph 2.


I see your point and agree, but you know and I know that there are BOs and plans examiners out there that will enforce the requirement as meaning "exterior exit doors at ground level" per your highlight.

June 6th, 2011, 12:53
I looked up the site using Google Earth. According to the link you provided the site plan does not show the entire site as it appears on Google Earth. It appears that building number 5 is connected to another structure. If the property line is at building 5 then the building cannot be unlimited.

The building beyond #5 as seen on Google Earth does not have the required 60-feet of clearance from another structure. The extreme northwest building’s southwest corner is too close to another structure (Lat 40° 8'53.04"N & Long 75° 0'7.43"W). Even if #5 is connected to and part of the entire building, the less than 60-ft would be an issue with unlimited area. IBC (2206) Section 507.5 does allow reduction to the 60-feet of clearance but there are some other requirements.

I assume you are the AHJ. I would have the Design Professional produce the documentation and calculations for your review. It sounds as if you are doing his job. He should do a Code Sheet quoting chapter and verse of the issues and / or solutions that your can check.

Hope we have been of some help.

June 6th, 2011, 13:06

crap ur right....I missed the building next to the extreme NW corner arrgh!!! vg thx u.

will check to see if the reductions allow it to still be unlimited...

I am working on the code analysis as the architect for the saladworks to submit to the AHJ (lower southampton twp PA).

yes the forum has been tremendously helpful....thank you very much.

any continued feedback is greatly appreciated as this project has stretched my mastery of the code - mostly small footprints vs. this large one...

at this point I was exploring "fire areas" for separating the occupancies as opposed to fire walls....but now better double back on the total overall size...this might trigger the need to get better intel on the use of fire walls to break this complex up into smaller buildings....

June 6th, 2011, 13:28
I totally agree with Architect1281 - if it's an unlimited area building, GOODBYE to the 10% accessory that many others on this post are claiming. Separate the A-2 spaces from the M use and the A-2's must be located adjacent to the perimeter of the building

June 6th, 2011, 15:50
You will have to review the proximity of the exiting building’s location and its type of construction to determine an assumed property line that will not affect the existing adjacent building. Of course we are assuming that the existing adjacent building has proper set backs from the property line. If not then maybe an assumed property line can be use between the two structures. You are dealing with an existing building and if there is already code issues due to allowable areas you may have to have a sit down with the AHJ.

I have designed projects, especially churches and schools, which have been added on by others and found that the additions have violated the allowable area even before Code changes occurred on the building areas. Some Architects and Building Owners just do not what to check allowable building areas and / or put in a firewall. They just want the put the addition on a forget the code.