Can an exit serve two buildings and be a separate building in and of itself?

[imhotep]

A developer and his engineer and architect are seeking to build an 18-plex apartment building: 3 stories, 6 units per floor. The original design has one exit per floor, which I say can't happen. IBC Section 1021 requires two exits from stories with more than four dwelling units. Six is greater than four, therefore two exits are required. The engineer comes back with a new proposal: what if we make it two buildings [with the required two-hour fire wall on the zero lot line] and make the exit a separate building between the two apartment buildings [now requiring only one exit per building] and enclose the exit within two-hour constructed walls? He is thinking that going from the balcony into the fire-rated exit "building" should be allowed, since the code doesn't dis-allow it. Has anyone dealt with someone wanting to construct an exit enclosure as a separate building and allow it to be used by two separate buildings on the same lot? The building footprint is at the maximum allowed by zoning to meet setbacks and height. Can you say 'frustration?' Any and all comments are appreciated. R-2 Occupancy, Type V-A construction with sprinklers.

Thanks, in advance. Carol

Interesting scenario. Appears possible. Providing two exits seems more practical.

IBC 2009 -

2 hour fire wall complying with 706.

Common path of egress travel complying with 1014.

Travel distance complying with 1016.

Egress balcony complying with 1019.

1 hour exit enclosure complying with 1022.

Accessibility?

 

[brudgers]

Here's why you tell them it won't work: if they are dividing it into two buildings, then you have an assumed lot line.

That is incorrect.

 

[mtlogcabin]

I hate to keep :beatdhrsbut common path of travel is not a part of the equation as described by the OP. There is no charging lanquage from Table 1021.2 or Section 1021.2 that will get you to 1014.3

As I said before the Maximum total travel distance permitted from the most remote space on the floor to an exit is 50 feet

2009 IBC

 

[texasbo]

That is incorrect.

Deleted

Edit: you're right - inaccurate language for this case. The OP said: " The engineer comes back with a new proposal: what if we make it two buildings [with the required two-hour fire wall on the zero lot line] and make the exit a separate building between the two apartment buildings ".

If the fire wall is built on the lot line between two buildings, per the OP, then the fire wall cannot have openings.

 

[Papio Bldg Dept]

Here's why you tell them it won't work: if they are dividing it into two buildings, then you have an assumed lot line. A fire wall at a lot line can have no openings.

deleted

edit:

Horizontal Exiting would not be possible if a lot line was established at every fire wall, and no openings were permitted.

 

[texasbo]

deletededit:

Horizontal Exiting would not be possible if a lot line was established at every fire wall, and no openings were permitted.

See my edit. However, the concept of horizontal exit keeps getting bandied about, and from what I can tell, that isn't even in play here, based on the OP. Ewenme hasn't clarified, but I THINK she is saying the latest proposal is a fire wall on a lot line between two buildings, and that would allow no openings.

 

[cda]

Does the two hour have to be on a lot line for the concept to work???

Or can't they just chop the building in two with the wall on the same lot???? And do the same concept

 

[texasbo]

Does the two hour have to be on a lot line for the concept to work???Or can't they just chop the building in two with the wall on the same lot???? And do the same concept

In this particular case, I don't think it matters. If they were trying to make it a horizontal exit (and there was no lot line), as has already been noted, it couldn't serve as the only exit.

 

[imhotep]

In this particular case, I don't think it matters. If they were trying to make it a horizontal exit (and there was no lot line), as has already been noted, it couldn't serve as the only exit.

Is it not the case that on a property line or off the entire structure would have to remain in a single ownership? If a lot line was established at the 2 hr fire wall for purposes of separating ownership then it would be a party wall and no openings are allowed.

 

[Examiner]

Is the FIRE WALL able to stand on its own upon collapse of the building on either side? Is the 2-hour FIRE WALL a true fire wall? If it is not then the EXIT Travel does not start over again. It has to be a true FIRE WALL to start exit travel over again. I do not recall anyone asking about the structural integrity of the FIRE WALL.

 

[texasbo]

Is it not the case that on a property line or off the entire structure would have to remain in a single ownership? If a lot line was established at the 2 hr fire wall for purposes of separating ownership then it would be a party wall and no openings are allowed.

Strictly by code, if there is a lot line, then no openings permitted. Some (including myself) have allowed legal documents to tie properties together under certain conditions.

 

[cda]

In this particular case, I don't think it matters. If they were trying to make it a horizontal exit (and there was no lot line), as has already been noted, it couldn't serve as the only exit.

Agree horizontal exit is not in play

 

[cda]

Is the FIRE WALL able to stand on its own upon collapse of the building on either side? Is the 2-hour FIRE WALL a true fire wall? If it is not then the EXIT Travel does not start over again. It has to be a true FIRE WALL to start exit travel over again. I do not recall anyone asking about the structural integrity of the FIRE WALL.

Has been asked a couple of times in different ways

Will it be cheaper to add another exit than to try to do the wall???

Maybe there is some site size limitation driving this???

 

[imhotep]

Agree horizontal exit is not in play

The OP implied the exit access was via a balcony. If this is the case then how is 1019 applied? 1/2 hr fire partition separating dwellings from balcony with rated doors & fire window assemblies.

 

[Papio Bldg Dept]

See my edit. However, the concept of horizontal exit keeps getting bandied about, and from what I can tell, that isn't even in play here, based on the OP. Ewenme hasn't clarified, but I THINK she is saying the latest proposal is a fire wall on a lot line between two buildings, and that would allow no openings.

The part I deleted addressed the difference between a horizontal exit fire wall and a party wall. In this case, if it is indeed on a lot line, then it shall be considered a party wall fire wall, and exiting through that wall is prohibited as a result of not allowing openings within a 0-3ft distance of the lot line. If a lot consolidation is performed to remove the lot line, then perhaps the horizontal exiting option would come into play, however, that could only account for 50% of the exiting.

I guess I remain confused on how many exits are being provided/utilized, and where an egress balcony comes into play here. Need more information perhaps.

I am also confused on why we continue to talk about the 50' travel distance for one means of egress. It seems apparent at this point that without some sort of alternative design or fire wall/horizontal exit at the unit to corridor connection, the 50' travel distance is no longer an option, and egress balconies do not factor as an increase until two means of egress are required.

Did I miss something?

 

[mtlogcabin]

Can an exit serve two buildings and be a separate building in and of itself?

Separate for what purpose?

1. To get around the maximum 4 units per story requirement for a single exit.

2. 503.1 General. allows a fire wall to create a separate building

3. FIRE WALL. A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall. A fire wall does not require a lot line be established

4. TABLE 706.4 footnote a only requires a 2 hour wall with Type V construction

5. TABLE 715.4 requires 1.5 hour opening protection for the door

6. 1022.6 Exit enclosure exterior walls.

Exterior walls of an exit enclosure shall comply with the requirements of Section 705 for exterior walls

7. 705.3 Exception: Two or more buildings on the same lot shall either be regulated as separate buildings or shall be considered as portions of one building if the aggregate area of such buildings is within the limits specified in Chapter 5 for a single building. Where the buildings contain different occupancy groups or are of different types of construction, the area shall be that allowed for the most restrictive occupancy or construction. This would allow the openings in the fire wall if the aggregate area of all buildings does not exceed the limitations in Chapter 5

8. A verticle exit enclosure is only required a one-hour rating when serving 3 floors

This is my understanding

All he is proposing is a 2 hour vertical exit enclosure installed between and serving 2 apartment buildings. He wants to call then separate buildings to get around the maximum 4 dwelling units per floor restriction.

I think code will permit the concept

With a single exit (the verticle exit enclosure) the problems are the travel distance limits and possible dead end corridor issue on the exterior balcony.

 

[ewenme]

Picture this: one story has six apartments, three on the left of the center "exit buidling" and three on the right. Now stack two more pancakes of the same flavor on top. You have three stories with six units each, however, the proposal is to make three buildings: nine units [3 per story] in one building, separated by a two-hour wall from the vertical exit enclosure, which we'll call building three, and a third building, which we'll call building two with 9 units [3 per story]. These buildings are all under one roof, and all on one lot. The footprint of the building is the maximum allowed by Zoning. The worst case scenario for exiting is from the end unit on the third story, 25 feet to exit the dwelling, onto the balcony that provides the access to the vertical exit; another 50-55 feet to the vertical exit, and then two flights of stairs to the exit discharge at grade. The basic questions are: can two separate buildings use the same exit? can the exit be considered a separate building?

MT: since the balcony is not enclosed with walls, it cannot be considered a corridor, so the dead-end corridor is not an issue. IMHO.

The whole structure will be sprinklered, as required by the IFC...even the balconies, as they have roof over and balcony over balcony.

THanks for additionl light you can shed.

Carol

 

[TJacobs]

Since it is on a single lot the firewall concept could create a horizontal exit since no party wall means openings OK. Question: once out on the egress balcony are you outside the whole time, on outside stairs, or do you reenter another building to access the stairs?

 

[mtlogcabin]

MT: since the balcony is not enclosed with walls, it cannot be considered a corridor, so the dead-end corridor is not an issue. IMHO.

1019.1 General.

Balconies used for egress purposes shall conform to the same requirements as corridors for width, headroom, dead ends and projections.

25 feet to exit the dwelling, onto the balcony that provides the access to the vertical exit; another 50-55 feet to the vertical exit

That is 75 to 80 feet of travel distance which exceeds

TABLE 1021.2

STORIES WITH ONE EXIT

MAXIMUM OCCUPANTS (OR DWELLING UNITS)

PER FLOOR AND TRAVEL DISTANCE

Third story

R-2c

4 dwelling units and 50 feet travel distance

It has to meet both requirements. It doesn't so require a second exit.

 

[gbhammer]

View attachment 1079something like this maybr with only one stair insted of two

View attachment 480

View attachment 480

/monthly_2011_09/build.jpg.0f9ddbbe36fbc6e2061f479fe4e42d03.jpg

 

[cda]

Mt

"""Can an exit serve two buildings and be a separate building in and of itself?""""

Been sick this week and no thinking straight, at least that is my story and sticking to it

Thought about after the post and know maybe in this situation it can work

 

[mtlogcabin]

Mt"""Can an exit serve two buildings and be a separate building in and of itself?""""

Thought about after the post and know maybe in this situation it can work

A verticle exit enclosure is normally constructed as a fire barrier under 707 if a designer wants to use 706 they can and if the AHJ wants to accept the design as separete buildings to meet exiting requirements I believe they can. If you wrap the apartments around the stair enclosure which will reduce the travel distance it will work it just doesn't work as described.

 

[brudgers]

Picture this: one story has six apartments, three on the left of the center "exit buidling" and three on the right. Now stack two more pancakes of the same flavor on top. You have three stories with six units each, however, the proposal is to make three buildings: nine units [3 per story] in one building, separated by a two-hour wall from the vertical exit enclosure, which we'll call building three, and a third building, which we'll call building two with 9 units [3 per story]. These buildings are all under one roof, and all on one lot. The footprint of the building is the maximum allowed by Zoning. The worst case scenario for exiting is from the end unit on the third story, 25 feet to exit the dwelling, onto the balcony that provides the access to the vertical exit; another 50-55 feet to the vertical exit, and then two flights of stairs to the exit discharge at grade. The basic questions are: can two separate buildings use the same exit? can the exit be considered a separate building? MT: since the balcony is not enclosed with walls, it cannot be considered a corridor, so the dead-end corridor is not an issue. IMHO. The whole structure will be sprinklered, as required by the IFC...even the balconies, as they have roof over and balcony over balcony. THanks for additionl light you can shed. Carol

For illumination: this is the sort of clusterflop you get when an engineer tries to play architect...or when a jurisdiction looks the other way on plan stamping.

 

[texasbo]

A verticle exit enclosure is normally constructed as a fire barrier under 707 if a designer wants to use 706 they can and if the AHJ wants to accept the design as separete buildings to meet exiting requirements I believe they can. If you wrap the apartments around the stair enclosure which will reduce the travel distance it will work it just doesn't work as described.

Ya, I'm buying into this in principle, now. No lot line, no horizontal exit. Just a complying fire wall (and all that that encompasses), dividing the spaces into separate buildings, and a properly constructed vertical exit enclosure, as long as travel distances are ok.