Reprising this post because folks keep asking me about it via email, etc.
These thresholds fit a three story apartment building or mixed use building into the fire/life safety requirements of the International Building Code (IBC) and the accessibility requirements of the Fair Housing Act.
1. All ground floor units are accessible/adaptable (minimum one unit).
2. TYPE V wood frame construction with fire sprinklers.
3. When built with a single stair, upper stories are limited to four units each. (more than 4 units on a floor and two stair will be required separated by a rated corridor at least 1/2 the diagonal of the building floor plate in length –1/3 for buildings with fire sprinklers.)
4. 2nd floor units are limited in size to 125′ max. exiting distance from the furthest point inside the unit to the entry door.
5. 3rd floor units are limited in size to 125′ max. exiting distance from the furthest point inside the unit to the entry door. (3rd floor units can be two story units with internal stairs as long as the max. exiting distance of 125′ is observed).
Code research and design by David Kim
A comment from Will Dowdy:
This is a good summary. It’s probably worth being explicit about that ground floor unit. If you don’t have a unit on the ground floor, the requirement for accessibility is shifted to the second floor of the building, which means that you’re stuck with an elevator. BIG problem. This design is an elegant solution.
rjohnthebad 
This is a good summary. It’s probably worth being explicit about that ground floor unit. If you don’t have a unit on the ground floor, the requirement for accessibility is shifted to the second floor of the building, which means that you’re stuck with an elevator. BIG problem. This design is an elegant solution.
John,
ola from Minnesota – so is the Fair Housing Act limit you to 4 units above for 1 unit on the ground floor? is that a ratio or could you design for more units above? M. Lamb
Mike Lamb, The Fair Housing Act requires all ground floor units to be accessible/adaptable in a building with 4 or more units. It is the International Building Code (IBC) that limits a building with a single means of egress (one stair) to 4 units on a floor. The IBC also limits the number of floors to 3 for a single stair walk-up. A single stair walk-up can have 8 units on the upper 2 floors, 4 units per floor under the IBC. Under the Fair Housing Act, a building with no elevator and 4 or more units in the building, must have at least one unit on the ground floor and all the ground floor units must be accessible/adaptable. The Fair Housing Act applies to buildings built after 1991.
ok, I get the IBC but I a s s u m e that doesn’t get a lot of attention with our first and second ring communities around here; so with your example if I wanted more units then I build another building….right?
Yes. Add more than 4 units per floor and you need to add a second stair and a ratted hallway separating them by at least 1/3 the diagonal of the floor plate. The size of the four units can be quite large, up to 4,000 SF in a sprinklered building. When you say the IBC does not get much attention in the first and second ring suburbs, what do they use as the model building code in Minnesota?
Real late to this discussion, but do you feel the accessible/adaptable requirement is either difficult or expensive that merits converting residential space to commercial? Over my 60+ years I seem to recall a lot of For Rent signs in ground floor commercial with residential above?
Is there absolutely no way to push a walkup to 4 floors with just a single stair? Type I construction perhaps? Fewer Units? For example, is a 4 or 5 story walkup with 1 unit per floor totally illegal under the IBC? Are (2) two story units spanning L3&L4 with internal stairs the only way to get another story?
You could have two story units on the third floor if you keep the travel distance for exiting the unit into the rated stair under 125 feet. Dig into the code section cited.
Looks like you are indeed correct. Table 1006.3.2(1) caps it at 3 floors, but interestingly it seems like the basement can have 4 dwelling units as well – affordable garden flats anyone?
I’ve been thinking about this problem a lot, and another solution I like is to use a scissor stair to get two means of egress while only paying for one rated stairwell.
I have a very similar Code issue (but it is under the 2013 CBC) with a 4 story building, 3 units; two, 2-story units at the top two floors each with access to a main enclosed stair to the street. And one flat below those (on the 2nd floor) all over a parking level. However, the 2-story units are entered at the 4th floor and farthest travel is right at the 125 foot limit. Plan checker is saying no, two exits required. And he is referencing a Code commentary to either 1021.1 or 1015.1 that says this layout is limited to three floors. Can’t find the commentary on that, Do you have a references that says this is OK?
Hi John:
Your page has disappeared from the web. Have you moved or deleted it?
Thanks,
Wynn Miller (719) 328-9220
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Hi John,
Are you ok with other developers borrowing/reusing these plans? I’d love to include a slightly modified version of this in a proposal I am putting together. Feel free to reach out to me directly (I assume you’re able to see my email address based on my login).
All the best – Matthew Denker
Matthew, Please use them and modify them as you need to. We have been very deliberately distributing these plans as Open Source, encouraging people to modify them as they need to. We offer the sharpened stick and encourage everyone to pick it up and go poke something. Occasionally this approach turns into some architectural work in a state where David Kim or Bruce Tolar is registered and we can help on the architecture side, but that is not the principal aim of the effort. The main thing is to get small scale, incremental buildings to happen. Keep us in the loop as to what happens with your proposal. Best, John
This design is great! I live in Baltimore and want to get involved in development, and designs like this would fit right in in the neighborhoods around downtown.
What’s the design program you used for the renderings?
David Kim did the rendered elevations using regular ol’ Photoshop on top of PDF line work from AutoCAD LT for Mac. I think his designs are elegant and straightforward. He is a genuine pleasure to work with.
John, I would actually question two parts of your code research. The ground floor unit appears to be designed as a Type B unit. FHA requires all ground floor units to be designed as Type B, but IBC Ch. 11 requires 2% of your units to be the more accessible Type A version. It’s my understanding that single ground floor unit would need to be designed as Type A. Second, I believe that the stair needs to be enclosed as a 1-hr exit enclosure, per 1022.2. Thoughts?
Stephanie, My able partner, David Kim will post a response in the next day or so on how the rating of the hallway and the configuration of the ground floor units works under the IBC.
Stephanie, the type A requirement only applies to buildings with over 20 units.
IBC 2009, 1107.6.2.1.1 Type A units. In Group R-2 occupancies containing more than 20 dwelling units or sleeping units, at least 2 percent but not less than one oftheunits shall be a Type A unit. All R-2 units on a siteshallbe considered to determine the total number of unitsand the required number of Type A units. Type A unitsshall be dispersed among the various classes ofunits.
ah HA! I usually gloss right over that since my typical project is 100+ units. Thanks for pointing that out!
Would it be possible to convert the den in the larger upper floor unit to a small bedroom? In my opinion this would make it more attractive. I heard somewhere that in order for a real estate listing to call a room a bedroom, it would need to have a closet.
The study is 10 x 12. Big enough for a full sized bed and an armoire. You could steal son space from the public rooms for a closet.
Well done!
If the building were three story on one side, and due to grades, two stories on the opposite side, could the ground floor accessible unit be on the second floor level, exiting to grade? Commercial floor would be below and residential above.
The first level that housing appears on is the “ground floor” under the fair housing act and all the units on that floor need to be accessible/adaptable.
And the stair is not considered a communicating stair because it is open to the exterior?
John,
This is a great resource. I see you have a boot camp coming up in Providence RI. Do you dive into all of these code interdependencies at your boot camp?
Ed
Yes. We have a session that my partner David Kim usually teaches called “Straightforward Design”. David is really good at navigating the codes to adapt the kind of basic buildings a small developer needs in their tool box and McGyvering the building Code, Fair Housing Act,ADA and the local zoning codes. Rather than just hand people canned solutions that we have worked out we try to use those as examples of how you can assemble the code hack that your project needs. More of a way of cooking with left overs and basic ingredients than high cuisine. Incremental development is like a really good omelet made from left overs with just the right spices, not a 4 course fancy dinner. Lately we have been looking at the Triple Decker building type as a building that can deliver a mixed use program and still qualify for a 30 year conventional mortgage.
John, David. This is such a good clarification of the code. Could you do this as a four story building for a total of 13 units? What is the elevator code max # of stories? I believe with wood sprinklers you can go 4 stories.
Wood frame with sprinklers can be four stories, but three stories is the maximum for a single stair with sprinklers. An elevator does not get you any more stories without a second stair , as the exiting in the event of a fire is assumed to be in the rated stair. Add another story or use more than four units per flor and you need a second means of egress, a second stair which needs to be separated with a rated corridor at least 1/3rd the diagonal distance of the floor plate. More stairs, more corridor to build and maintain. You coul build some or all of the third floor units as double height units with a mezzanine or interior second level, but the travel distance from the farthest point in the upper level to the rated stair enclosure cannot exceed 125 feet.
Looking for clarity on the two-story unit on the 3rd level. Does that mean the building is actually 4 stories? The 125′ is distance is measured to the “entry door” of the building, or the unit? (Assuming building.)
The central stair serves 3 floors. A dwelling unit on the third floor can have an internal stair and the exit distance is measured from the farthest point in the 3rd floor unit to the units entry door at the rated exit stair. That 125′ metric is measured inside the third floor (two story unit)
Hi John
Quick question. I am designing a 6 apartment building, 2 per floor with a single stair. I’m designing both the first floor apartments to be accessible units.
The owner would like to look at the option of a loft in each of the first floor apartments or as a second option on the third floor.
For the first floor option I planned on designing a mezzanine over a bedroom so that the first floor is still a single story. The loft would be open to the living below. Is there a maximum height for a story?
For the second option it looks like I may do more than a loft and can do a whole floor as long as I meet the travel distance to the exit. Correct?
Monica
The top floor can have two story units with internal stairs or a mezzanine with internal stairs within the unit. You just need to keep the max travel distance to the central exit stair to less than 125′. I apologize for the delay in responding to you.
No problem and thank you for responding. Have you come across a code section that specifies a maximum height for a story by any chance?
Thanks, John. Appreciate the quick response! I’m sorry if I’m being dense, but I still just want to be sure I’ve understood about the 4th floor potnetial: The third floor, two-story unit occupies a portion of the third floor and also a portion of a 4th floor. The 4th floor is access through a stair that is internal to the unit. The distance from the farther point of travel from inside the unit to that unit’s front door is 125′ (which seem plenty generous.)
There is no fourth floor. The central stairs only go to the third floor and provide access to the units. Those units can have mezzanines and internal stairs, (or they could be full two story units) as long as the total travel distance from the farthest point in the unit to the central exit stair is less than 125′. Fours story buildings can be built with TYPE V wood framing and fire sprinklers, but you will need a second stair and the two stairs need to be separated with a rated corridor that is at least 1/3rd the diagonal dimension of the building floor plate. At four stories with two stairs and a rated corridor you are no longer limited to four units per floor. The four units per floor is for a three story, single stair sprinklered TYPE V wood frame building.
This is great! Do you know what the estimated lot size is for this plan?
That will depend upon what your local zoning code requires for the minimum amount of off-street parking. If the site has an alley in the rear the site can be a small as 100′ wide and 70′ deep. That would provide 9 off-street parking spaces with one accessible space and room for a trash enclosure and a surface mounted transformer in the rear of the site.
I am currently working on a similar layout. The code official has indicated that the 125 foot travel distance is from the most remote point on the third floor inside a unit to the exit discharge. (IBC 2009 1014.3 exception 4 refers to “common path of egress travel”)
Your analysis indicates I have 125′ to the door of the unit but this is not the exit discharge, rather it is the entry to the stair. Is your analysis based on the stair being a vertical exit enclosure with one hour rating?
Thank you.
Yes. The stairway needs to be rated exit enclosure. It could also be detailed as a rated but unconditioned breezeway open to the rear of the building.
Suppose you’re rehabilitating an old 2-story building (1920’s) into an apartment and want to start with the second floor. Does there have to be an elevator? Would they have to put at least one accessible ground floor unit in to avoid installing an elevator?
Thanks, John. I just watched your excellent CNU video of the same. Would you care to explain what 1/3 the diagonal of the floor plate means? The reason I’m asking is to find out what would be required to build a 3-story 130-ft by 80-ft plan with two staircases serving eight units per floor.
Measure diagonally from one corner of 130 x 80 rectangle to the opposite corner. The entry doors for each of your exit stairs have to be separated by at least 1/3rd that distance in a building built with fire sprinklers. You could avoid creating all that corridor/common area by building two buildings each with a single stair. 40 x 80 with a 20 El and a 2 hour rated wall separating the two structures. This would produce a U shaped footprint and provide an entry court.
Thank you very much. As to why one building rather than two: Aren’t four walls are cheaper than six, and energy easier to conserve within one envelope?
Sure, but 80×130 corridor building is going to have more common area and that is not just a first cost, but it will have an impact on your ongoing operating expenses. Also a corridor building creates lots of units with windows on only one side of the unit. Also, it’s not just what it costs. It’s what it cost _and_ what it makes. A courtyard building is way better for the reside
Is there anywhere in the IBC code we can confirm that a 4 storey high residential building requires elevator?
The IBC doesn’t require an elevator for a fourth story. It does require a second means of egress and a rated corridor at least 1/3rd the diagonal measurement of the floor plate in length separating the access to the two exit stairs in TYPE V. construction with fire sprinklers.
This is a great analysis! However, I’m wondering if you’ve contemplated a modification to this design to introduce an optional elevator. We are currently working with a very similar 3-storey design where the Owner is requesting that an elevator be installed for convenience. However, I’m running into a stumbling block as it pertains to 2012 IBC Section 1022.4 where it indicates “Elevators shall not open into interior exit stairways and ramps.”
You would need to create an alcove off of the exit circulation path for the elevator. The first cost and maintenance cost of an elevator are significant. Installing an elevator will also move you into a higher tier of construction labor. I don’t think convenience will generate the additional revenue to support the higher costs, but people can do what they want with their buildings. I just don’t like the math.
Adding an elevator would also require every unit to meet accessibility correct?
All units in an elevator building are considered “covered units” and must be accessible/adaptable.
john what are the lot sizes for this model? I assume more contemporary styling is option for the buildings?
The building shown is 74’ x 40’. We
designed a 97’ x 30’ three story Walk-up for Matthew Petty in Fayetteville to fit on a site that was very shallow with shred parking on the adjacent lot. The design is intended to illustrate the solutions to the thresholds of the International Building Code for Single stair egress in a three story sprinklers building along with the Fair Housing Act requirement for all ground floor units in a non-elevator building of 4 units or more to be Accessible/Adaptable. The architectural style or massing could be anything you think would be marketabl(subject to any local design review requirements).
Hi! If the site is sloped, and the retail is on street level, with parking on the back, one level up, and three stories residential above (4 units per floor x 3 floors off a center lobby) then, does code allow three stories above and can we skip the elevator?
Retail is on Floor 1 accessed from the street. With four units of residential on FL2 accessed from the parking level, you can have a third floor with another four units. Three stories total, measured from the lowest level. If there are no residential units on the 1st floor, then the Fair Housing Act considers level 2 to be the “Ground Floor” of a non-elevator building and all four of those units must be Accessible/Adaptable. You only get threes stories in a non-elevator building and the IBC would not consider the retail level a “basement”.