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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