14B-10-1011  Stairways.
The provisions of Section 1011 of IBC are adopted by reference with the following modifications:
1.   Revise exception 3 to Section 1011.2 by replacing “Group R-3” with “Group R-3 or R-5.”
2.   Revise Section 1011.3 by replacing “80 inches (2032 mm)” with “7 feet (2134 mm).”
3.   Revise exception 2 to Section 1011.3 to read:
“2.   The required headroom clearance shall be not less than 80 inches (2032 mm), and where the nosings of treads at the side of a flight extend under the edge of a floor opening through which the stair passes, the floor opening shall be allowed to project horizontally into the required headroom not more than 4 3/4 inches (121 mm) in any of the following conditions:
2.1.   In Group R-3 and R-5 occupancies.
2.2.   Within dwelling units in Group R-2 occupancies.
2.3.   In Group U occupancies that are accessory to a Group R-3 occupancy or accessory to individual dwelling units in Group R-2 occupancies.”
4.   Revise Section 1011.4 to read:
1011.4 Walkline.
Where a stair includes winder treads, the walkline shall comply with Section 1011.4.1 or 1011.4.2.
1011.4.1 Other than Group R-5 occupancies and within dwelling units.
The walkline across winder treads in other than R-5 occupancies and within individual dwelling units in Group R-2 occupancies shall be concentric to the direction of travel through the turn and located 12 inches (305 mm) from the side where the winders are narrower. The 12-inch (305 mm) dimension shall be measured from the widest point of the clear stair width at the walking surface of the winder. Where winders are adjacent within the flight, the point of the widest clear stair width of the adjacent winders shall be used.
1011.4.2 Group R-5 occupancies and within dwelling units.
The walkline across winder treads in R-5 occupancies and within individual dwelling units in Group R-2 occupancies shall be concentric to the direction of travel through the turn and located 18 inches (457 mm) from the side where the winders are narrower.”
5.   Revise exception 3 to Section 1011.5.2 to read:
“3.   The maximum riser height shall be 8 inches (203 mm), the minimum tread depth shall be 9 inches (229 mm), the minimum winder tread depth at the walkline shall be 9 inches (229 mm) and a nosing projection not less than 1 inch (25 mm) but not more than 1 1/4 inches (32 mm) shall be provided where the tread depth is less than 10 inches (254 mm) in any of the following conditions:
3.1.   In Group R-3 and R-5 occupancies.
3.2.   Within dwelling units in Group R-2 occupancies.
3.3.   In interior and exterior stairways in Group R-2 occupancies serving only units that are not required to be Accessible units or Type A units.
3.4.   In Group U occupancies that are accessory to a Group R-3 occupancy or accessory to individual dwelling units in Group R-2 occupancies.”
6.   Revise Section 1011.5.3 to read:
1011.5.3 Winder treads.
Winder treads are not permitted in means of egress stairways.
Exceptions:
1.   Curved stairways in accordance with Section 1011.9.
2.   Spiral stairways in accordance with Section 1011.10.
3.   Within or serving a building of Group R-3 or R-5 occupancy.
4.   Within a dwelling unit in a Group R occupancy.”
7.   Revise exception 1 to Section 1011.5.5.3 to read:
“1.   Solid risers are not required for interior stairways that are not required to comply with Section 1009.3, provided that the opening between treads does not permit the passage of a sphere with a diameter of 6 inches (152 mm).”
8.   Revise exception 4 to Section 1011.5.5.3 to read:
“4.   Solid risers are not required for exterior stairways that are not required to comply with Section 1009.3.”
9.   Revise Section 1011.6 to read:
1011.6 Stairway landings.
There shall be a floor or landing at the top and bottom of each stairway. The width of landings, measured perpendicularly to the direction of travel, shall be not less than the width of stairways served. Every landing shall have a minimum depth, measured parallel to the direction of travel, equal to the width of the stairway or 48 inches (1219 mm), whichever is less. Doors opening onto a landing shall not reduce the landing by more than one-quarter the required width. Where wheelchair spaces are required on the stairway landing in accordance with Section 1009.6.3, the wheelchair space shall not be located in the required width of the landing and doors shall not swing over the wheelchair spaces.
Exceptions:
1.   Where stairways connect stepped aisles to cross aisles or concourses, stairway landings are not required at the transition between stairways and stepped aisles constructed in accordance with Section 1029.
2.   Where doors are allowed by Section 1010.1.5.”
9.1.   Revise Section 1011.7 to read:
"1011.7 Stairway construction.
Stairways shall be built of materials consistent with the type of construction of the building.
Exceptions:
1.   Stairways connecting five or more stories shall be built of and supported by noncombustible materials. Shaft enclosures for stairways connecting five or more stories shall be built of noncombustible materials.
2.   Wood handrails shall be permitted for all types of construction."
10.   Revise the exception to Section 1011.7.3 by replacing “Group R-2 or R-3” with “Group R-2, R-3 or R-5.”
11.   Revise Section 1011.8 to read:
1011.8 Vertical rise.
A flight of stairs shall not have a vertical rise greater than 12 feet (3658 mm) between floor levels or landings.
Exceptions:
1.   Spiral stairways used as a means of egress from technical production areas.
2.   In Group R-3 and R-5 occupancies a flight of stairs may have a vertical rise not greater than 151 inches (3835 mm) between floor levels or landings.”
12.   Revise the exception to Section 1011.9 by replacing “Group R-3” with “Group R-3 and R 5.”
13.   Revise the first sentence of Section 1011.10 to read:
Spiral stairways are permitted to be used as a component in the means of egress only within dwelling units, serving a single dwelling unit, from a space not more than 250 square feet (23 m2) in area and serving not more than five occupants or from technical production areas in accordance with Section 410.5.”
14.   Revise Section 1011.11 to read:
1011.11 Handrails.
Flights of stairs shall have handrails on each side and shall comply with Section 1014. Where glass is used to provide or support the handrail, the handrail or support shall comply with Section 2407.
Exceptions:
1.   Flights of stairs within dwelling units and spiral stairways are permitted to have a handrail on one side only.
2.   Decks, patios and walkways accessory to Group R-5 occupancies or individual dwelling units that have a single change in elevation where the landing depth on each side of the change of elevation is greater than what is required for a landing do not require handrails.
3.   Where allowed, a change in elevation consisting of a single riser at an entrance or egress door does not require handrails.
4.   Changes in elevation of three or fewer risers within or accessory to individual dwelling units and sleeping units in Group R-2, R-3 and R-5 do not require handrails.
5.   Flights of stairs that serve as stepped aisles for seating areas shall have handrails either at one or both sides of the aisle or within the aisle width.”
15.   Revise Section 1011.12 to read:
1011.12 Stairway to roof.
In buildings with four or more stories above grade plane, one stairway shall extend to the roof surface unless the roof has a slope greater than or equal to three units vertical in 12 units horizontal (25-percent slope).
Exception: Other than where required by Section 1011.12.1, in buildings without an occupiable rooftop, access to the roof from the top story shall be permitted to be by an alternating tread device, a ship's ladder or a permanent ladder.
16.   Revise Section 1011.12.2 to read:
1011.12.2 Roof access.
Where a stairway is provided to a roof, access to the roof shall be provided through a penthouse complying with Section 1510.2.
Exception: In buildings without an occupiable rooftop, access to the roof shall be permitted to be a roof hatch or trap door not less than 16 square feet (1.5 m2) in area and having a minimum dimension of 2 feet (610 mm).”
17.   Revise Section 1011.14 by adding the following after the last sentence:
“The minimum clear width at and below the handrails shall be 20 inches (508 mm).”
18.   Delete the exception to Section 1011.14.2.
19.   Revise the second sentence of Section 1011.16 to read:
“Permanent ladders shall be constructed in accordance with the Chicago Mechanical Code.”
(Amend Coun. J. 2-19-20, p. 14473, Art. II, § 45; Amend Coun. J. 10-7-20, p. 21791, Art. II, § 23))