Building w/one exit - R2 use group

[Scott555]

2009 IBC - New Jersey Edition
Type VB
Three Stories
R-2 Use w/ S-2 private garages on one side of bldg. at grade
No basement
Fully sprinklered
10 units per building/fire area (2 + 4 + 4)

Ground floor: 2 units one side of bldg, 6 individual private garages on other side. 2 means of egress provided from corridor to exterior.
2nd and 3rd floors: 4 units/floor. Units exit to corridor and to one exit stair as per sections 1021, 1022 and table 1021.2

Questions:
1. Does the exit stair on floors 2,3 need to be an exit enclosure or can the stair be open?
2. If a fire barrier (2 hour) is provided, can modules of 10 units be attached to create a 20 and 30 unit building? Each fire area will have 4 units/story per exit.

Thank you,
Scott

[Jerry Peck - Codeman]

Scott,

My first glance through says:
1. That exterior stair may be able to be an open stair with some separation requirements to make it an exterior stair - I will need to read through again tomorrow and make sure that I have considered the different options and exceptions.
2. What are the areas of: Each floor? The building? The S-2 and the R-2 on the first floor?

[Scott555]

The stair is interior, not exterior...
First floor is S-2 and R-2, the upper floors are R-2.

Thanks.

[Jerry Peck - Codeman]

Okay, the stair is an interior stair, that helps.

First, you have one exit, which is allowed under certain conditions, being fully sprinklered as you said is only one of the conditions, such as:
- maximum travel distance of 50 feet (you might meet that, depending on the layout)
- maximum occupant load of 20 per dwelling unit 'and' the sprinkler system must meet 903.3.1.1 or 903.3.1.2 (I am presuming the sprinkler system meets one of those)
- the third story units must also have emergency escape and rescue openings

With that out of the way, let's get back to:
- 1. Does the exit stair on floors 2,3 need to be an exit enclosure or can the stair be open?
- - Because it is an "exit stair" is an "exit", and the definition of "exit" is:
- - - "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 the level of exit discharge, vertical exit enclosures, exit passageways, exterior exit stairways, exterior exit ramps and horizontal exits."

Thus the answer is: Yes, the exit stair needs to be enclosed.

[Jerry Peck - Codeman]

[Scott555]

Jerry - as far as open stairs, I read it that no more than 2 stories of stairway can be "open".

As far as question #2 of course I want to "go there" as that is why I asked the question. I meet all the tabular area, height requirements with sprinklers so that is not the issue as far as overall building. I have a building broken into three fire areas with fire separation walls. Each fire area has no more than 4 units per floor and has one exit enclosure per fire area (table 1021.2 "stories with one exit").

Does this meet the intent?

[Jerry Peck - Codeman]

[Scott555]

[Jerry Peck - Codeman]

Scott,

Let's start over - you are painting a picture with words and I am trying to assemble that same picture in my mind.

See below for what I have envisioned, either A or B, but there are other configurations which would also fit what you are describing. How close am I with A or B?

4 unit apt.jpg

[Scott555]

Jerry - more like A except the stair is in between unit 1 and 3. There is no corridor between 1/2 and 3/4 as that is a party wall.

[Jerry Peck - Codeman]

Okay, I will redraw it with the stair between 1 and 3, with the stair egress door opening into a common area, and with 2 and 4 meeting at the center of the common area wall.

That means 1 and 3 are slightly smaller than 2 and 4 - correct?

[Scott555]

Yes... (?) but that isn't the crux of the question and I think we are getting hung up on it. All I am looking for is can I repeat the module (assuming all other issues like travel distance, sprinklers, etc are met) and have up to three "pods" put together separated with fire walls (area separation walls) and still qualify as intended for table 1021.2 which is one exit per 4 units per STORY. Each pod will have it's own egress stair. The overall floor area will be under 7,000 sf.

[Jerry Peck - Codeman]

I understand the crux of the question, understanding the layout allows refining the options and the applicable code.

One condition allowing one exit is 4 or fewer dwelling units PER STORY, and two pods equals 8 dwelling units per story.

That is what I need to re-read again.

You can't just choose a way to use an exception and then violate the allowances for the exception.

[Jerry Peck - Codeman]

Scott,

This is what you have as one "module", correct? Or close to this.
4 unit apt01.jpg

This is what you are thinking of doing, correct?
4 unit apt02.jpg

[Scott555]

Yes and Yes. The maximum would be three modules with total area per floor less than 7,000 sf.

[Jerry Peck - Codeman]

You would have 8 units per story that way and would need two exits for each.

This would be a better module:
4 unit apt01b.jpg

Then, when you added another module, you would automatically be adding another exit. All you would need to do is make sure the dead ends were less than 20 feet, and that could be done by adding a wall at the dead end and creating storage there:
4 unit apt02b.jpg

[Scott555]

Jerry, I appreciate all your time & efforts in graphic representations, etc.
I am not looking for design solutions. This is a time sensitive issue for a client who is purchasing an already approved site plan with this concept. I simply need a yes or no on the concept of having one exit per 4 units and if a fire barrier accomplishes that or not. If you feel it does not please state why and cite a section. If it does or if it is a grey area that is not specifically addressed in the IBC, please say so.

If you are not sure, that is fine too - I will pose this question to IBC directly.

[Jerry Peck - Codeman]

[Scott555]

How do I insert an image to show the concept? The Img icon doesn't allow me to select the image from my computer, just gives me: ?

[Jerry Peck - Codeman]

Scott,

Click on 'Upload attachment' to the right of 'Options' below the 'Submit' button, then click the 'Browse' button to select a file on your computer, then click 'Add the file', you can add a comment either before clicking 'Add the file' or afterward at the next step.

The maximum file file size is 256 KB. What file type (extension) are you trying to load?

[Scott555]

Jerry - it's a jpg
When I click on the Img icon all that comes up is syntax

[Scott555]

typ floor copy.jpg

[Jerry Peck - Codeman]

Scott,

That's what I was saying, that wall you are showing as a 2-hour separation wall will need to be a full firewall and may need to be 2-hours or 3-hours, and the intent of that wall would not be to separate the two fire areas, but to separate the two halves into separate "buildings".

Only then can I see that you 'may' be able to get by with 1 egress exit for each "building", and each "building" must be able to stand alone structurally should the "building" on the other side of the firewall collapse.

That would be one of those calls which the AHJ would need to make, and same AHJ may give it to you and others AHJ may not.

The way to solve that problem is to actually separate those halves into separate buildings, i.e., construct two separate "exterior walls' which are fire-rated for the lack of physical separation between them. That way you have two separate buildings with, say, a 3 foot to 5 foot walkway between them. Yes, I know, this does not work with your modular plan, but it is a way to solve the problem.

My guess is that many AHJ will recognize a full firewall as creating two separate and distinct, but attached, "buildings", and that they will also recognize that you are doing that to avoid having to provide two separate egress exits for the one common structure - even though you have provided two separate egress exits, they are not accessible to the other part of the structure.

I believe you will have a harder time selling this to the local Fire Marshals than to the AHJ for the building structures.

I, for one, would have a hard time swallowing that plan as it is a deliberate attempt to get around providing two separate egress exits for the one structure.

And when there is an emergency and someone is injured or dies, you can count on one thing for sure - that they will come looking for you, with your name at the top of the "Defendants" list, because it was you who chose to try to get around the two accessible egress exits.

What I'm saying is that you may be able to get some AHJ, and a few Fire Marshals (but probably not many), to sign off on your plan, but at what cost? Especially when a simple revision would solve the problem.

You would not be able to have any utilities in that common firewall as each "building" would need to be able to stand alone. Think of it as being able to slice down that firewall as though you were cutting a loaf of bread and removing one half - the other half would need to be able to stand alone ... no common fire sprinklers, no common wiring, no common anything.

And, yes, to another question of yours: each stair would likely need to be the exit and would need to be contained within its own firewalls. If there is an exception which would allow this not to be a fully protected exit, I would not want to apply that exception - I would want to make sure that anyone escaping from a unit will be protected and safe within the stair enclosure all the way down to the exit discharge, which, by the way, should be opening outward in the direction of egress (the left one is shown as opening inward while the right one is shown as opening outward).

Just some thoughts off the top of my head.

[Scott555]

Thanks for all your input Jerry.

I am aware of area separation walls having to stand if one side falls. This would be achieved with the US Gyp core wall system (like in town house design). So, I have 50' from most remote point in corner bedroom, building is separated into 2 bldgs. via an area separation wall able to collapse and leave one side standing, does this meet the building with one exit at 4 units per floor criteria? And if corridor walls and doors to units are rated accordingly - I should be able to do this, correct? Also, what does AHJ stand for?

[Jerry Peck - Codeman]

Hi Scott,

AHJ stands for Authority Having Jurisdiction, i.e. the local building department, or more specifically the local Building Official.

According to the sections of the building code we went over, and what I could find, yes, you "should" be able to do what you are describing, but there are many local and/or state variances in the building code, plus the interpretation of the AHJ (Building Official), and the fact that the fire prevention and life safety codes have opening for interpretations too, and the Fire Marshals are the authority to interpret the fire code and life safety codes, that, all added together, may make it so that some areas may well allow what you are proposing and other areas may not allow it.

Will your modules be frame, poured concrete, or masonry? A masonry wall (or a formed and poured concrete) firewall between the two buildings would be my preference to build as there is a greater chance for what you are proposing to be accepted versus constructing that firewall of wood frame and gypsum board.

Can you construct that firewall using wood frame and gypsum board? Sure, but a masonry wall is more substantial, has fewer chances for errors, and is more forgiving, than building a wood frame wall with multiple layers of gypsum board.

Just food for thought in trying to make your project more likely to be accepted given all the variables and interpretations which could be placed on your design such that two egress exits would be required.

What it will come down to is the knowledge and experience of the AHJ and the Fire Marshall and if you can convince them to allow what you are proposing. Code is seldom a cut and dried 'yes' or 'no' answer, much of the time code has a 'it depends' answer.

All things considered, the answer may well be 'it depends' on the local Building Official and Fire Marshall and local amendments to the code which was adopted for that area. I'm not being negative, just realistic on the way things are done and how things work out at times.

The saying is that if there are 10 building officials in the room, there will likely be at least 8 different opinions, and sometimes 12 different opinions as they change their minds on how they are reading it.

[Scott555]

Thanks Jerry - I think I have enough to go on now...I appreciate all the hard work you have put into this!