2021 IBC Chapter 10
Lesson 9 sized the system. This lesson covers the parts a person actually touches on the way out: doors, stairs, ramps, handrails, and guards, plus the lights and signs that keep the path findable in smoke or a power failure. Most punch-list findings on community buildings, multifamily rehab, and small commercial walk-throughs come from here. Section numbers are 2021 IBC; several moved from 2018.
Section 1010.1.1 requires a clear opening at least 32 inches wide, measured between the face of the door and the stop with the door open 90 degrees, and at least 80 inches high. On a pair of doors with no mullion, one leaf must provide the 32 inches. Older handouts teach a 48-inch maximum leaf width; the 2021 text has none, so do not cite one. A level floor or landing at the same elevation is required on each side of a door (1010.1.4); exterior landings may slope up to 2 percent. Thresholds may rise no more than 1/2 inch (3/4 inch for sliding doors serving dwelling units), and any change over 1/4 inch is beveled (1010.1.6). A landing at a door (1010.1.5) is at least as wide as the door or stair, whichever is greater, and 44 inches long in the direction of travel; an open door may not cut into it by more than 7 inches.
Handles, pulls, latches, and locks sit between 34 and 48 inches above the floor (1010.2.3). Releasing all latches takes one motion (1010.2.1), and hardware on accessible doors may not require tight grasping, pinching, or twisting of the wrist (1010.2.2). Under 1010.1.3, push or pull hardware unlatches with 15 pounds and rotating hardware with 28 inch-pounds. An interior swinging door that is not fire-rated opens with 5 pounds; other swinging, sliding, and folding doors and all fire-rated doors take 30 pounds to set in motion and 15 to reach full open. Forces are measured at the latch side.
Doors swing in the direction of egress where they serve a room with an occupant load of 50 or more or any Group H space (1010.1.2.1). Under 1010.2.9, a swinging door serving Group H, or a room of 50 or more in Group A or E, may have no latch or lock other than panic hardware or fire exit hardware. Key locks on the egress side are the narrow exception: 1010.2.4 allows them on main doors in Group A with a load of 300 or less and in B, F, M, S, and places of worship, if the lock is readily distinguishable as locked, a durable sign with 1-inch letters says the door stays unlocked when occupied, and the official may revoke the allowance.
Stairs are at least 44 inches wide, or 36 inches where they serve an occupant load under 50 (1011.2), with 80 inches of headroom measured vertically from a line through the nosings (1011.3). Risers are 7 inches maximum and 4 inches minimum. Rectangular treads are at least 11 inches deep. Winders need 11 inches at the walkline and 10 inches within the clear width. Group R-3, dwelling units in R-2, and accessory Group U may use 7-3/4-inch risers and 10-inch treads; that allowance does not carry over to a Group A or B stair (1011.5.2). Within a flight, the largest and smallest riser, or tread, may differ by no more than 3/8 inch (1011.5.4). Nosings may project no more than 1-1/4 inches (1011.5.5.1). One flight may rise no more than 12 feet between floors or landings (1011.8). Landings at the top and bottom are as wide as the stair and as deep as the stair width or 48 inches, whichever is less (1011.6).
Worked example: floor to floor in a Group B community office is 11 feet 4 inches, or 136 inches. At a 7-inch maximum riser, 136 divided by 7 is 19.4, so the stair needs 20 risers of 136 divided by 20, or 6.8 inches each. Twenty risers mean 19 treads, and at 11 inches each the run is 209 inches, about 17 feet 5 inches. The 136-inch rise is under the 144-inch (12 foot) flight limit, so no intermediate landing is needed; at 13 feet floor to floor (156 inches) one would be.
An egress ramp runs no steeper than 1:12, about 8.3 percent, with a cross slope no steeper than 1:48 (1012.2, 1012.3). Other pedestrian ramps may reach 1:8. A single run rises no more than 30 inches (1012.4), which at 1:12 is 30 feet of run, so a taller change needs a landing between runs. Width is at least the corridor width in Table 1020.3, with 36 inches clear between handrails (1012.5.1). Landings at the top, bottom, turns, and doors are level to 1:48, as wide as the widest run, and at least 60 inches long (1012.6). Handrails on both sides are required where the rise is over 6 inches (1012.8), and edge protection is required at each side of runs and landings (1012.10).
Stair flights need a handrail on each side (1011.11); flights inside a dwelling unit and spiral stairs may have one. Handrail height is uniform and measured 34 to 38 inches above the stair nosings or ramp surface (1014.2). A round Type I rail is 1-1/4 to 2 inches in diameter; a non-round rail has a perimeter of 4 to 6-1/4 inches (1014.3.1). Clear space between the rail and the wall is at least 1-1/2 inches (1014.7), and the grip must be continuous, not interrupted by newel posts (1014.4). Where the rail is not continuous between flights, it extends 12 inches horizontally past the top riser and slopes for one tread depth past the bottom riser (1014.6). On a wide stair, every part of the width must be within 30 inches of a handrail, which is what intermediate rails are for (1014.9).
A guard is required along an open-sided walking surface, including mezzanines, platforms, aisles, stairs, ramps, and landings, that is more than 30 inches above the floor or grade below at any point within 36 inches of the edge (1015.2). Guards are at least 42 inches high, but only 36 inches in Group R-3 up to three stories and within R-2 dwelling units up to three stories (1015.3). Openings must stop a 4-inch sphere from the walking surface up to the required height. The exceptions are a 4-3/8-inch sphere between 36 and 42 inches, a 6-inch sphere in the triangle at the stair riser, tread, and bottom rail, and a 21-inch sphere at equipment access surfaces and in non-public areas of I-3, F, H, and S (1015.4).
Normal-power illumination is at least 1 foot-candle at the walking surface and at least 10 foot-candles on stairways and landings while the stair is in use (1008.2.1). Emergency power must last at least 90 minutes and average at least 1 foot-candle at the start, with no point below 0.1 foot-candle, and the light may fade to 0.6 average and 0.06 minimum by the end (1008.3.4, 1008.3.5). Exit signs must be visible from any direction, with every point in a corridor within 100 feet of a sign or the listed viewing distance, whichever is less (1013.1), and doors to exit stairs and discharge get raised-character and braille signs (1013.4). Exits discharge directly outside or by a direct path to grade, and no more than 50 percent of the number and width of interior exit stairs may discharge through the level of discharge (1028.2).
For assembly spaces, a main exit serving a load over 300 must carry at least half the occupant load (1030.2). Aisle widths are in 1030.9.1, and Group B and M aisles are never narrower than the corridor width in Table 1020.3 (1018.3).
In the field
A church wants to use its second-floor fellowship hall for after-school programs. The inspector finds a 40-inch stair with a 7-1/4-inch top riser over 6-3/4-inch risers below, a handrail on one side only, and a guard at the landing with 5-inch gaps. That is four findings on one stair: width against the load served, riser height and uniformity, the missing second rail, and the 4-inch sphere. Bring a tape and a 4-inch gauge, measure every riser in the flight, and check both handrail ends for extensions.
1. A single side-hinged door on the egress path of a Group B office is opened 90 degrees. What is the minimum clear opening width under 2021 IBC Section 1010.1.1?
2. An inspector measures a threshold 3/4 inch high at a side-hinged exterior door serving a Group M store. What is the most a threshold may rise under 1010.1.6 for this door?
3. An inspector hangs a spring scale on the latch side of an interior swinging door in a Group B corridor. The door is manually operated and not fire-rated. What is the most force allowed to push or pull it open?
4. A Group A-2 nightclub has an occupant load of 400, and the swinging door from its main room to the outside has a keyed deadbolt in addition to the latch. What does 1010.2.9 require on this door?
5. A stair in a Group B building serves an occupant load of 40 people. What is the minimum stair width under 1011.2?
6. An inspector finds 7-1/4-inch risers and 11-inch treads on an interior stair in a Group A-3 community hall. What is the problem?
7. Within one flight of a Group E stair, the smallest riser measures 6-1/2 inches and the largest measures 7 inches. What does 1011.5.4 say about this flight?
8. A Group B stair must connect floors 106 inches apart. With a 7-inch maximum riser, what is the fewest risers that can be used?
9. What is the maximum vertical rise of a single stair flight between floors or landings under 1011.8?
10. An inspector measures the height of a stair handrail in a Group R-2 common stair at 33 inches above the nosings. Under 1014.2, what is the finding?
11. A handrail in a Group A-3 building is not continuous between two flights. How far must it extend horizontally past the top riser of a flight, under 1014.6?
12. A mezzanine walkway in a Group S-1 warehouse is 8 feet above the floor and has an open side. What is the minimum guard height under 1015.3?
13. A Group B egress ramp must rise 24 inches. At the steepest running slope allowed for an egress ramp, what is the shortest run?
14. What is the minimum illumination on a Group B exit stairway and its landings while the stairway is in use, under 1008.2.1?