Building Code and Building Construction - Questions and Answers
Or when you want to know how construction is supposed to be done.

|
AskCodeMan.com
|

Custom Search

Building w/one exit - R2 use group

Building w/one exit - R2 use group

New postby Scott555 on Tue Oct 25, 2011 8:56 pm

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
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Wed Oct 26, 2011 12:10 am

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?
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Wed Oct 26, 2011 10:15 am

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

Thanks.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Wed Oct 26, 2011 8:13 pm

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
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Wed Oct 26, 2011 8:18 pm

Scott555 wrote: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.


Before addressing any other part of the above, you would now eliminate the allowances/exceptions which are allowing for the one egress exit stairway you have.

I'm not sure you want to go there as that will affect other things too.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Wed Oct 26, 2011 9:32 pm

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?
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Wed Oct 26, 2011 10:29 pm

Scott555 wrote:Jerry - as far as open stairs, I read it that no more than 2 stories of stairway can be "open".


You referred to the stair as an "exit" stair, and all parts of the "exit" which are inside the structure need to be separated from the structure.

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?


That would not meet the intent of the exception allowing a single exit - that is the first thing I was getting at.

That would mean making sure all the exits (corridors, stairs, etc.) met all the requirements for exits. This would include dead ends, common path of travel (if any), travel distance, egress width for the increased occupant load, etc., unless you were going to have two exits for each group of two, which would mess up your modular stacking plan. That was where I was starting from.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Thu Oct 27, 2011 8:55 am

Scott555 wrote:That would mean making sure all the exits (corridors, stairs, etc.) met all the requirements for exits. This would include dead ends, common path of travel (if any), travel distance, egress width for the increased occupant load, etc., unless you were going to have two exits for each group of two, which would mess up your modular stacking plan. That was where I was starting from.


Perhaps I am not explaining this correctly? I have 4 units per floor with one exit stair in a common area (it is a "pod" concept with all 4 units exiting into a common area and there is the stair in the center of the 4 units leading to grade (now enclosed as you have stated...). Then on the outside wall of the end unit - a fire separation wall. The plan of 4 units is mirrored. Each group of 4 units has it's own fire exit stair - so the building would have 2 stairs - just 4 units serving each stair independently.
There is a 2 module and 3 module plan.

No dead end corridors, travel distances are met, etc.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Thu Oct 27, 2011 9:36 pm

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
You do not have the required permissions to view the files attached to this post.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Thu Oct 27, 2011 11:01 pm

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.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Fri Oct 28, 2011 9:37 am

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?
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Fri Oct 28, 2011 10:57 am

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.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Fri Oct 28, 2011 12:18 pm

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
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Fri Oct 28, 2011 9:00 pm

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
You do not have the required permissions to view the files attached to this post.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Fri Oct 28, 2011 9:37 pm

Yes and Yes. The maximum would be three modules with total area per floor less than 7,000 sf.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Fri Oct 28, 2011 10:09 pm

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
You do not have the required permissions to view the files attached to this post.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Fri Oct 28, 2011 11:00 pm

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.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Sun Oct 30, 2011 12:02 pm

Scott555 wrote: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.


Scott,

Before answering your question I had to first understand what you were describing, and then I thought I did answer your question with this in a post above:
Jerry Peck - Codeman wrote:One condition allowing one exit is 4 or fewer dwelling units PER STORY, and two pods equals 8 dwelling units per story.


To be more concise: No, you cannot do what you are proposing by separating the modules with a fire barrier. To further answer your question (I realize you did ask for a 'yes' or a 'no', but in the codes many things are 'it depends', which does not seem to be satisfactory for you) you 'may' be able do what you are proposing with fire walls as the fire walls are creating two separate, although attached, building.

And with two separate buildings, you 'may' be able to treat each one as an individual as with your modules.

When using fire barriers, you would need to adapt your design to compensate for it, because, again, the answers in the code are frequently 'it depends'.

Start with the definition of "fire barrier":
- Fire Barrier. A fire-resistance-rated wall assembly of material designed to restrict the spread of fire in which continuity is maintained.

Then go to "fire wall":
- 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 the collapse of construction on either side without collapse of the wall.

Fire walls are allowed to be used to separate buildings which are close together or attached - as your modules will be.

Now we need to go to "story":
- Story. That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above (also see "Basement", "Mezzanine" and Section 502.1). It is measured as the vertical distance from the top to top of two successive tiers of beams or finished floor surfaces and, for the topmost story, from the top of the floor finish to the top of the ceiling joists or, where there is not a ceiling, to the top of the roof rafter.

Provided the AHJ accepts a fire wall (not a fire partition) as dividing the modules into separate buildings, then, 'yes', you could stack modules next to each other and still only have 4 dwelling units per story, however, if the AHJ does not accept the fire wall (not a fire partition) as dividing the modules into separate buildings, then, as I pointed out above, 'no', because you would now have 8 dwelling units per story and that would not meet one of the allowances for having only one exit.

You now have your 'yes' and 'no', and the also frequent 'it depends' as you would need to change what you are doing, and you do not seem to be willing to change what you are doing.

Thus, because you will not be changing what you are doing (there is no indication that you are willing to do so), the final and single answer to your question of whether or not you can do what you propose to do with fire barriers is:
- "No."

For code references, start with the reference you gave as 1021 which states that all spaces within each story shall have the minimum number of exits in Table 1021.1 (which is two exits minimum) and then has some exceptions which allow for the use of only one exit, and when referring to Table 1021.2 you will see that there is a maximum of 4 dwelling units per story.

You want a simple answer to a complex question, which is not unusual, it is just that you will not get what you want that way.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Sun Nov 06, 2011 11:03 pm

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: ?
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Mon Nov 07, 2011 6:45 pm

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?
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Tue Nov 15, 2011 11:33 am

Jerry - it's a jpg
When I click on the Img icon all that comes up is syntax
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Scott555 on Tue Nov 15, 2011 11:37 am

typ floor copy.jpg
You do not have the required permissions to view the files attached to this post.
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Tue Nov 15, 2011 11:48 pm

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.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Thu Nov 17, 2011 12:18 pm

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?
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am

Re: Building w/one exit - R2 use group

New postby Jerry Peck - Codeman on Thu Nov 17, 2011 9:31 pm

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.
Jerry Peck - CodeMan
AskCodeMan.com
Construction Litigation Consultant - Retired
Construction and Code Consultant - Semi Retired
User avatar
Jerry Peck - Codeman
Site Admin
 
Posts: 1199
Joined: Fri Dec 12, 2008 12:06 pm

Re: Building w/one exit - R2 use group

New postby Scott555 on Fri Nov 18, 2011 8:07 pm

Thanks Jerry - I think I have enough to go on now...I appreciate all the hard work you have put into this!
Scott555
 
Posts: 26
Joined: Wed Apr 27, 2011 10:37 am


Return to Egress: Means of Egress (other than stairways, see 'Stairways' below)



Who is online

Users browsing this forum: No registered users and 2 guests


cron