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    IBC 2015 R-2 Single Exit with duplex apartments

    IBC 2015 R-2 Single Exit with duplex apartments

    New postby bbehin on Tue Dec 13, 2016 4:20 pm

    Hello Jerry,

    I'm writing about an R-2 project in New Jersey, IBC 2015 NJ Edition.

    It is a three or four story building (more on that below), less than four units per floor (less than 10 occupants per unit), sprinklered,

    I would like to use 1006.3.2 "Single Exits", condition 1 (table 1006.3.2(1)), which allows one exit for R-2 occupancies up to the third floor above grade, as long as the building is sprinklered, there are four or less units per floor, "maximum common path of egress travel distance" is 125 feet, and bedrooms are equipped with emergency escape and rescue openings.

    1) If the third floor units are duplexes, with living space at the fourth floor, bedrooms on the third floor only (having emergency escape and rescue openings on the third floor), an internal unenclosed stair in each unit connecting the third and fourth floor areas of the units, and the front door of the duplex units providing access to a single exit stair on the third floor, am I still allowed to have just one exit if the path of travel is kept below 125 feet? I think I've seen something like this built under a previous version of the code, and am wondering if the 2015 code allows it.

    2) How do you interpret "common path of egress travel distance" when there's just one exit? Is the 125 feet from the furthest point inside the unit to a rated exit corridor or exit stair? Is it possible to avoid a rated stair if the the travel distance from the furthest point within a unit on the top floor to the main building exit door to the public right-of-way at grade is less than 125 feet?

    Thank you
    Behrang
    bbehin
     
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    Re: IBC 2015 R-2 Single Exit with duplex apartments

    New postby Jerry Peck - Codeman on Tue Dec 13, 2016 8:20 pm

    Behrang,

    bbehin wrote:I'm writing about an R-2 project in New Jersey, IBC 2015 NJ Edition.

    It is a three or four story building (more on that below), less than four units per floor (less than 10 occupants per unit), sprinklered,

    I would like to use 1006.3.2 "Single Exits", condition 1 (table 1006.3.2(1)), which allows one exit for R-2 occupancies up to the third floor above grade, as long as the building is sprinklered, there are four or less units per floor, "maximum common path of egress travel distance" is 125 feet, and bedrooms are equipped with emergency escape and rescue openings.


    Reading the above, and hearing the hounds baying as they went away, I jumped on the closest hunt horse and began the chase ... looking up the code and reviewing it.

    Just as I came upon the hounds, a staff member yelled "Tally Ho" ... and that is when I noticed that the fox had run the hounds in a circle and back into their kennels:

    1) If the third floor units are duplexes, with living space at the fourth floor, bedrooms on the third floor only (having emergency escape and rescue openings on the third floor), an internal unenclosed stair in each unit connecting the third and fourth floor areas of the units, and the front door of the duplex units providing access to a single exit stair on the third floor, am I still allowed to have just one exit if the path of travel is kept below 125 feet? I think I've seen something like this built under a previous version of the code, and am wondering if the 2015 code allows it.


    I was trying to figure out what you meant with the term "duplex apartments" and "duplexes" because "duplexes" is typically used to describe two dwelling units attached, i.e., "a duplex" which contains two dwellings.

    When I read 1), I realized you were using the term to mean "two-story" apartments - apartments which consisted of two stories, one floor above the other floor.

    That is when I saw that the fox had the hounds back in their kennels - you are referring to a four-story building.

    It does not matter if the four-story building contains one-story apartment units on each floor; whether it contains four-story apartment units; whether there are two levels of two-story apartment units; or any mix of one- two- three- or four-story apartment units ... the building is still a four-story building.

    From the definitions in the 2015 New Jersey Building Code, that is a four-story building, with all four stories being above grade (see the following definitions):
    2015 NJ BC story definition.jpg


    Thus we will go back to the code sections you referenced - 1006.3.2 and Table 1006.3.2(1):
    - Table 1006.3.2(1) and Table 1006.3.2(2) allow for a single exit under the stated conditions for the each table.
    - - Table 1006.3.2(1):
    - - - allows one exit for: "basement, first, second or third story above grade plane" and "with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 and provided with emergency escape and rescue openings in accordance with Section 1030"
    - - - does not allow one exit for: "Fourth story above grade plane or higher".
    - - - it also says "This table is used for R-2 occupancies consisting of dwelling units. For R-2 occupancies consisting of sleeping units, use Table 1006..3.2(2)

    As the building you are describing contains apartments (dwelling units), we are limited to Table 1006.3.2(1), thus there is no need to go to Table 1006.3.2(2).

    I see what you are trying to do:
    - a) use the fact that dwelling units only require one egress and emergency escape and rescue openings
    - b) thus the "fourth story" is thus exempt from having a second exit

    However, 1006.3.2 and Table 1006.3.2(1) does not include the exemption from a second exit that you are wanting to apply.

    Table 1006.3.2(1) (which is titled: "Stories with one exit or access to one exit for R-2 Occupancies") specifically states: (in column one under "Story") "Fourth story above grade plane or higher", (and in column two under "Occupancy") "NP"; the notes to the table state that "NP = Not Permitted"

    Let's start with the title to the table: "Stories with one exit or access to one exit for R-2 Occupancies". A key word in there is "or", thus that table applies to: "Stories with one exit" ... "or" ... "access to one exit" ... "for R-2 Occupancies". In the case of the building you are describing, the "or access to one exit" may be the best described limiting factor as the third floor two-story units only have "access" to one exit.

    From there we go down to "Fourth story above grade plane or higher" under "story" in column one as that is the story in question, we then proceed to the right to column two, up to the heading which states "Occupancy", then back down to see what is allowed in that fourth story above grade plane, and the table says "NP", which means "Not Permitted". That means the fourth floor in the building you describe is thus "not permitted" to have the fourth story occupied as there is only one "access" to an exit (and that is on the third story) - as described, your building does not have "even one" "access" to an exit for the fourth story, your building has *no* "access" to any exits - all you are proposing to have as "exits" are the emergency escape and rescue openings.

    Which means there is no reason to even go here at this time:
    2) How do you interpret "common path of egress travel distance" when there's just one exit? Is the 125 feet from the furthest point inside the unit to a rated exit corridor or exit stair? Is it possible to avoid a rated stair if the the travel distance from the furthest point within a unit on the top floor to the main building exit door to the public right-of-way at grade is less than 125 feet?
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    Re: IBC 2015 R-2 Single Exit with duplex apartments

    New postby bbehin on Tue Dec 13, 2016 10:08 pm

    Jerry,

    Thank you for the prompt, thorough (and poetic!) response. Sorry for the confusion. Yes,by 'duplex', I meant a two-story dwelling unit. I was hoping that based on 1006.3, which states that "the path of egress travel to an exit shall not pass through more than one adjacent story", we could rely on access to the floor 3 exit from the fourth floor through the third floor, but I understand based on your reading that Table 1006.3.2(1) explicitly forbids occupancy on the fourth floor with access to a single exit when employing condition (1) of 1006.3.2.

    We may end up keeping the project only 3 stories tall in order to achieve the single exit, since the building footprint is small enough that adding another exit stair and a corridor means you don't get much bang for the buck with the fourth floor.

    Your response is much appreciated - it is very helpful. If you don't mind, please let me know what you think about a related issue on a different project:

    I am starting another project with a related issue, where I'm hoping to employ 1006.3.2 condition 5, which allows multistory dwelling units to have access to a single exit from the dwelling unit if that exit access leads to two independent exits outside of the dwelling unit's entrance.

    It is a four story R-2 building. Floor 1 is parking. Two exit stairs lead from grade/public right of way to a corridor on floor 2. The building has six three-story apartments, all starting at floor 2 and going up to floor 4. All the three-story apartments have access to two exits via the floor 2 corridor. So, for example, the exit access path for the top level of an apartment (at floor 4) is through an internal unenclosed stair in the apartment connecting floors 4,3, and 2. At floor 2, one can leave the apartment through its entrance door and gain access to two independent exits from the floor 2 corridor. Each apartment has less than 10 occupancy load and 125 feet travel distance (counting the internal stairs) to its entrance, at which the common path of egress travel ends since two exits are available at the two ends of the corridor.

    My reading of 1006.3.2.5 is that this is allowed. However, given that 1006.3 states "the path of egress travel to an exit shall not pass through more than one adjacent story", can 1006.3.2.5 be employed for a three-story dwelling unit or does 1006.3 limit the number of stories of a multi-story dwelling unit under 1006.3.2.5?

    Also, I assume table 1006.3.2(1) doesn't apply here since it only applies if using condition 1006.3.2.1

    Thank you again!
    Behrang
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    Re: IBC 2015 R-2 Single Exit with duplex apartments

    New postby bbehin on Tue Dec 13, 2016 11:18 pm

    Jerry,

    In case the description of the second project in my previous note wasn't clear, here is a simplified diagram illustrating the basic arrangement.

    Thank you!
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    Re: IBC 2015 R-2 Single Exit with duplex apartments

    New postby Jerry Peck - Codeman on Tue Dec 13, 2016 11:26 pm

    If you don't mind, please let me know what you think about a related issue on a different project:

    I am starting another project with a related issue, where I'm hoping to employ 1006.3.2 condition 5, which allows multistory dwelling units to have access to a single exit from the dwelling unit if that exit access leads to two independent exits outside of the dwelling unit's entrance.

    It is a four story R-2 building. Floor 1 is parking. Two exit stairs lead from grade/public right of way to a corridor on floor 2. The building has six three-story apartments, all starting at floor 2 and going up to floor 4. All the three-story apartments have access to two exits via the floor 2 corridor. So, for example, the exit access path for the top level of an apartment (at floor 4) is through an internal unenclosed stair in the apartment connecting floors 4,3, and 2. At floor 2, one can leave the apartment through its entrance door and gain access to two independent exits from the floor 2 corridor. Each apartment has less than 10 occupancy load and 125 feet travel distance (counting the internal stairs) to its entrance, at which the common path of egress travel ends since two exits are available at the two ends of the corridor.[/quote]

    I presume that you are measuring in rectilinear paths with 90 degree angles, not diagonals, from farthest point to doorways, stairs, etc.

    My reading of 1006.3.2.5 is that this is allowed. However, given that 1006.3 states "the path of egress travel to an exit shall not pass through more than one adjacent story",


    That section and its wording, like many sections of the code, taken in and of itself, can state one thing, but what it states is modified by its subsection, in this case, 1006.3 is modified by 1006.3.1 where 1006.3.1 says "A single exit or access to a single exist shall be permitted in accordance with Section 1006.3.2." - that now offers 1006.3.2 as an option. And 1006.3.2 Single exits, offers five options, with option 5. including "multistory dwelling units" and states that those multistory dwellings "shall be permitted to have a single exit or access to a single exit from the dwelling unit provided that both of the following criteria are met:" ... and that is what you are meeting: 5.1 sprinklered and 5.2 access to two exits.

    Convoluted wording to be sure as it starts off about "single exits" and ends up with "not less than two approved independent exits" - which is a contradiction for a "single exit".

    can 1006.3.2.5 be employed for a three-story dwelling unit or does 1006.3 limit the number of stories of a multi-story dwelling unit under 1006.3.2.5?


    My reading it that 1006.3 includes its subsection 1006.3.1, and 1006.3.1 references 1006.3.2 which allows a single exit from a multistory dwelling as long as ... (blah, blah, blah) ... is met.

    Also, I assume table 1006.3.2(1) doesn't apply here since it only applies if using condition 1006.3.2.1.


    Correct. 1006.3.2, option 1 references Table 1006.3.2(1), while option 5 does not, option 5 has its own specific two requirements which need to be met.

    Sometimes the code is written quite clear, as in 'you shall do this' or 'you are permitted to do this', while other sections of the code actually seem to contradict each other at times - but I didn't write the code (the code may have ended up worse if I had ... yikes!).

    End result, yes, the code says you can have a multistory dwelling unit with one access to two exits. That common corridor is going to be sprinklered too, I presume, and rated, along with the stairs, to serve as an exit access as may be required.
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    Re: IBC 2015 R-2 Single Exit with duplex apartments

    New postby bbehin on Wed Dec 14, 2016 9:56 pm

    Jerry,

    Thank you for the explanation. Yes, the path will be measured at right angles, and the corridor will be sprinklered, and corridor and stairs will be rated.

    Many thanks for your help

    Best Regards
    Behrang
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