In Chicago, stairs have to meet the Chicago Building Code (Title 14B). It’s based on IBC 2018 with city amendments. The main stair rules are: risers 4″–7″, treads at least 11″, headroom at least 7′-0″, stairs at least 44″ wide (36″ under 50 occupants), handrails on both sides at 34″–38″, and guards at least 42″ high. Below are the sections I check before a stair goes to inspection, and where Chicago is different from the plain IBC.
Code note: I took these from the public text of the Chicago Building Code 2019 (Chapter 14B-10) on UpCodes, which shows the city amendments. Codes get amended, so check the current text on the City of Chicago building code page or the ICC copy of Chapter 10, and have the stair checked by the architect and the engineer of record. For accessible stairs, the 2010 ADA Standards apply too.
Which code covers stairs in Chicago?
The Chicago Building Code, Title 14B of the Municipal Code. It adopts IBC 2018 with amendments. Stairs, handrails and guards are in Chapter 10, Means of Egress: Sections 1011 (stairs), 1014 (handrails) and 1015 (guards). You can read it on the city’s site or buy the code book or just the amendments.
What are the riser and tread rules?
| Rule | Chicago Building Code | Section |
|---|---|---|
| Riser height | 4″ min, 7″ max, measured nosing to nosing | 1011.5.2 |
| Tread depth | 11″ min, measured nosing to nosing | 1011.5.2 |
| Residential exception | 8″ riser max, 9″ tread min (R-3, R-5, inside R-2 units, some R-2 stairs). A 1″–1¼” nosing is needed where the tread is under 10″ | 1011.5.2 Exc. 3 |
| Uniformity | 3/8″ max difference in a flight | 1011.5.4 |
| Winders | Not allowed in means of egress stairs (except curved, spiral and residential) | 1011.5.3 |
| Nosing curve or bevel | 1/16″ to 9/16″ | 1011.5.5 |
| Nosing projection | 1¼” max, uniform | 1011.5.5.1, 1011.5.5.2 |
Chicago’s residential exception is looser than the IBC 2021 one (7¾” riser, 10″ tread). Check which one your job falls under.
Do Chicago stairs need solid risers?
Yes, by default. Section 1011.5.5.3 requires solid risers, vertical or sloped under the tread up to 30° from vertical. Open risers are allowed on:
- interior stairs that don’t have to meet 1009.3 (accessible means of egress), if a 6″ sphere can’t pass between the treads,
- I-3, and F, H and S occupancies outside public areas,
- spiral stairs,
- exterior stairs that don’t have to meet 1009.3.
The 6″ sphere is a Chicago value; IBC 2021 uses 4″. More on open risers in my open riser steel stairs post.
How wide do stairs have to be in Chicago?
- 44″ min (1011.2).
- 36″ min for a stair that serves a story with an occupant load under 50 and isn’t part of an interlocking stair group.
- 48″ clear between handrails if the stair is part of an accessible means of egress, unless the building is fully sprinklered (1009.3.2).
- The width must not get narrower in the direction of travel.
What headroom and rise are allowed?
- Headroom: 7′-0″ (84″) min, measured up from the line of the nosings (1011.3). Spiral stairs: 78″. Residential (R-3, R-5, inside R-2 units): 80″.
- Rise of one flight: 12′-0″ max between floors or landings (1011.8). R-3 and R-5: 151″.
What are the landing rules?
Section 1011.6:
- A landing (or floor) at the top and bottom of every stair.
- At least as wide as the stair.
- At least as deep as the stair width, but it doesn’t have to be more than 48″.
- A door opening onto the landing can’t reduce it by more than one-quarter of the required width. That’s a Chicago change; IBC 2021 allows one-half.
- Wheelchair spaces, where required (1009.6.3), can’t be in the required landing width.
What about the walking surface?
- Slope: 1:48 (2%) max in any direction (1011.7.1).
- Solid surface. Openings (grating, for example) must not pass a ½” sphere, with the long side across the direction of travel. In F, H and S occupancies, 1⅛” (1011.7.1 exceptions).
- Outdoor stairs have to be designed so water won’t pool on the walking surfaces (1011.7.2).
What are the handrail rules in Chicago?
| Rule | Chicago Building Code | Section |
|---|---|---|
| Where | Both sides of every flight. One side allowed in dwelling units and on spiral stairs | 1011.11 |
| Height | 34″–38″ above the nosings, uniform | 1014.2 |
| Round rail | 1¼”–2″ OD | 1014.3.1 |
| Non-round rail | 4″–6¼” perimeter, 1″–2¼” cross section, 0.01″ min edge radius | 1014.3.1 |
| Continuity | Continuous, not interrupted by posts | 1014.4 |
| Extensions | 12″ level past the top riser; slope one tread depth past the bottom riser. Return to a wall, guard or the floor, or continue to the next flight | 1014.6 |
| Wall clearance | 1½” min | 1014.7 |
| Projection into width | 4½” max each side | 1014.8 |
| Intermediate rails | Every part of the required width within 30″ of a handrail | 1014.9 |
So a wide stair needs a middle rail much sooner than many people think. With 30″ max to a rail, anything over about 60″ wide needs one.
For modeling the rails, see handrails in Advance Steel.
What are the guard rules in Chicago?
| Rule | Chicago Building Code | Section |
|---|---|---|
| Where | Open sides more than 30″ above the floor or grade below | 1015.2 |
| Height | 42″ min, measured from the nosing line on stairs | 1015.3 |
| Openings | No 4″ sphere up to 36″; no 6″ sphere from 36″ to 42″ | 1015.4 |
| Stair triangle | No 6″ sphere through the riser/tread/bottom rail triangle | 1015.4 |
| Industrial | 21″ sphere in non-public areas of I-3, F, H, M and S, and at equipment platforms | 1015.4 |
The 6″ sphere between 36″ and 42″ is a Chicago value. IBC 2021 uses 4⅜”.
Do I need a stair to the roof?
In buildings with four or more stories, one stair has to go to the roof, unless the roof slope is 3:12 (25%) or steeper (1011.12). If there’s no occupiable roof, a ship’s ladder, alternating tread device or permanent ladder can be used instead, except where elevator equipment on the roof needs maintenance. Then it has to be a stair (1011.12.1).
What gets stairs failed most often?
These are the easy ones to miss:
- Uneven risers. 3/8″ max difference, including at the top and bottom where the floor finish changes the height.
- Treads measured from the riser instead of nosing to nosing.
- Handrails on only one side.
- Handrail extensions left off at the top or bottom.
- Guard openings checked against the IBC 4⅜” instead of Chicago’s numbers, or the other way around on a job outside the city.
Where’s the ADA stair template?
If the stair has to be ADA compliant, I have an Advance Steel template in my ADA compliant stairs post.
If you’re looking at hardware or software upgrades, my toolbox page lists the tools I use and any discounts I know of.
