Interpretation of California Building Code -- CBC section 1010.1.6 and CBC 1011.5.2: Interior vs. Exterior stairs

[B_olantis]

I'm having a disagreement with a city reviewer on building plans. The issue at hand is a residential multi-unit ADU (4 units, one structure, each with their own exit). Two units on top, two units on bottom. The two units on the upper floor each propose having their own exterior stairway going down. Each unit is a 3 bed unit.

The reviewer is insisting that the landing width serving the second story units in the direction of egress (width of stairs) be 44" and that the maximum rise be 7 inches, however they accept that the stairway should be 36" wide minimum.

The section of code they referenced for this is CBC section 1010.1.6: “Landings at Doors..." be 44" in direction of egress, however that section states an “Exception: Landing length in the direction of travel in Groups R-3 and U and within individual units of Group R-2 need not exceed 36” (914mm).” It's a stairway serving an individual unit within group R-2, so I'm thinking it should be 36", the same width as the stairs.

They are saying that it only applies to indoor stairways of group R-2 (I think they're going off the word "within" in the exception comment) -- I'm thinking the intention of the code is for exterior as well. I couldn't find an exact distinction, but did see in https://codes.iccsafe.org/s/IBC2018P6/chapter-10-means-of-egress/IBC2018P6-Ch10-Sec1010.1.6 "Landings shall have a width not less than the width of the stairway or the door, whichever is greater". In this case, neither the door nor stairway have to be more than 36".

I'm having a hard time imagining the landing would have to be wider than the stairs?

On the same token for CBC 1011.5.2, they are saying the stairs have to be 7" max rise....same exception for group R-2, but they're saying it only applies to stairs on interior of R-2 units, and not exterior stairs? Any suggestions for clarification?

 

[arwat23]

The section of code they referenced for this is CBC section 1010.1.6: “Landings at Doors..." be 44" in direction of egress, however that section states an “Exception: Landing length in the direction of travel in Groups R-3 and U and within individual units of Group R-2 need not exceed 36” (914mm).” It's a stairway serving an individual unit within group R-2, so I'm thinking it should be 36", the same width as the stairs.

Like you said, the key word here would be "within". Exterior isn't "within" the unit, so my reading is this exception wouldn't apply. They should be referencing CBC 1010.1.5.

They are saying that it only applies to indoor stairways of group R-2 (I think they're going off the word "within" in the exception comment) -- I'm thinking the intention of the code is for exterior as well. I couldn't find an exact distinction, but did see in https://codes.iccsafe.org/s/IBC2018P6/chapter-10-means-of-egress/IBC2018P6-Ch10-Sec1010.1.6 "Landings shall have a width not less than the width of the stairway or the door, whichever is greater". In this case, neither the door nor stairway have to be more than 36".

This section is not in the 2022 CBC, so it's not applicable (unless this project is using 2019 CBC). It was removed (revised to address a different requirement) in the 2021 IBC / 2022 CBC.

In my opinion, the landing needs to be 44" wide based on the comment you received.

 

[steveray]

Yeah....I think the thinking is exterior stuff is "common" so it is a different standard....

 

[Yikes]

Can you post a plan of the stair and landing in question?
I can't tell whether you are referring to a top or bottom landing, or the position of the door relative to the landing and I don't know why you are using the 2018 IBC.
Have you also looked at 2022 CBC 1011.6 for stair landings?

 

[Paul Sweet]

I think the intent of the code is for stairs serving only a single dwelling unit. Unfortunately the verbiage doesn't match the intent.

 

[B_olantis]

Can you post a plan of the stair and landing in question?
I can't tell whether you are referring to a top or bottom landing, or the position of the door relative to the landing and I don't know why you are using the 2018 IBC.
Have you also looked at 2022 CBC 1011.6 for stair landings?

Here's a picture of what (I think?) they're basically saying -- is it in direction of door opening, or direction of stairs? Either way, I did look at that section [https://codes.iccsafe.org/s/CABC202...hall be a floor,the width of stairways served.], and it seems to back up the point that the stairway landing in the direction of egress shouldn't be longer than 36" since neither the door nor stairs are wider than 36".

The other issue is the 7" rise they are specifying ... I looked up the most recent 2022 code [https://codes.iccsafe.org/s/CABC202...ight and tread depth.,inches (102 mm) minimum.] and the verbiage is: "in Group R-3 occupancies; within dwelling units in Group R-2 occupancies; and in Group U occupancies that are accessory to a Group R-3 occupancy or accessory to individual dwelling units in Group R-2 occupancies; the maximum riser height shall be 73/4 inches (197 mm); the minimum tread depth shall be 10 inches (254 mm);"

Still has the "within dwelling units in Group R-2 occupancies"...but not sure what they mean by "or accessory to individual dwelling units in Group R-2 occupancies", but seems like their intent was for both interior/exterior. Can't see why you'd allow a larger step height just because it's indoors. Has anyone ever emailed "cbsc@dgs.ca.gov" on code clarifications, and if so, how long did their replies take?

 

[Yikes]

Is your door swinging outward onto the landing, or inward?

 

[B_olantis]

Is your door swinging outward onto the landing, or inward?

Inward