Commercial Stair Codes

**Bruce Breedlove** · 02-03-2010, 01:14 AM

I did an inspection today on a small commercial building (a former restaurant) and I am wondering if the same codes for residential stairs (riser height, handrail height, handrail openings, etc.) apply for a commercial building. I will not cite code in the report; I am simply asking if the same - or similar - codes apply.

The riser heights vary. The first two sets are about 5" to 5-1/2". The top set are about 7". I am assuming this nonuniformity does not meet code.

The stairs are covered with snow because the building is vacant and the steps are on the north side. We had a very cold December and January and the little snow we have gotten is hanging around in the shaded areas a lot longer than normal.

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**Bruce Breedlove** · 02-03-2010, 01:17 AM

The top of the pipe rails are 30" to 32" high. The openings between the pipe rails are MUCH greater than 4" (or 4-1/4"). Are these rail heights within the acceptable range?

**Bruce Breedlove** · 02-03-2010, 01:18 AM

Also, handrails are on only one side of the stairs. Should a handrail be added to the other side? If so, at what stair width is the second handrail required?

**Markus Keller** · 02-03-2010, 07:12 AM

Times like this make me wish I could remember who borrowed my IBC. I need to just go buy a new one. Riser height from what I remember is supposed to be no more than 7 1/2". Tread depth 10". Guardrails I think min. 36" +/-. Don't think the spacing rule applies. Handrail on both sides required for 44" or wider around here. I'm sure Jerry will show up soon and provide detailed info.
Are you doing a PCR?

**Fred Weck** · 02-03-2010, 08:13 AM

Commercial stairs have been 4" minimum rise, 7" maximum rise, with 11" minimum run with max 3/8" variation for a long time. Handrail height changed in the 80's, so may have been correct when it was built.
The larger steps if they have a 36" run could have been considered landings, and the riser height could vary more than the 3/8".

Told a commercial builder to tear out a new set of stairs last week that had a 10" run.

**H.G. Watson, Sr.** · 02-03-2010, 11:08 AM

IIRC stairways.org has some free download documents on the visual interpretation of the stair codes, including the IBC. At least I recall their being a document which incorporated the 2003 IBC. You might check them out, if the IBC is the code in question. Assume that is an alternate exit, not required to be ADA accessible as I see no ramp. Other codes may speak to the subject (fire code, etc.) as well, depending on the occupancy, location, etc.

I recall a handrail extension requirement at commercial at least a tread depth in the IBC.

Hard to know vintage of building, if UBC BOCA, etc. different specs for handrail height, extension, min/max riser, run, and depths for landings w/ or w/o door swing.

**Bruce Breedlove** · 02-03-2010, 11:44 AM

Originally Posted by H.G. Watson, Sr.

IIRC stairways.org has some free download documents on the visual interpretation of the stair codes, including the IBC.

Thanks. That's good to know. I'll check it out.

Originally Posted by H.G. Watson, Sr.

Assume that is an alternate exit, not required to be ADA accessible as I see no ramp.

The ADA access is from the other direction.

**Jerry Peck** · 02-03-2010, 06:21 PM

From the 2006 IBC. (underlining and bold are mine)
- 1009.1 Stairway width. The width of stairways shall be determined as specified in Section 1005.1, but such width shall not be less than 44 inches (1118 mm). See Section 1007.3 for accessible means of egress stairways.
- - Exceptions:
- - - 1. Stairways serving an occupant load of less than 50 shall have a width of not less than 36 inches (914 mm).

- - - 2. Spiral stairways as provided for in Section 1009.8.
- - - 3. Aisle stairs complying with Section 1025.
- - - 4. Where an incline platform lift or stairway chairlift is installed on stairways serving occupancies in Group R-3, or within dwelling units in occupancies in Group R-2, a clear passage width not less than 20 inches (508 mm) shall be provided. If the seat and platform can be folded when not in use, the distance shall be measured from the folded position.

Not many restaurants will have an occupancy of less than 50, meaning the minimum width would be 44 inches.

- 1009.3 Stair treads and risers. Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads. The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread’s leading edge. Winder treads shall have a minimum tread depth of 11 inches (279 mm) measured at a right angle to the tread’s leading edge at a point 12 inches (305 mm) from the side where the treads are narrower and a minimum tread depth of 10 inches (254 mm).
- - Exceptions:

- - - 1. Alternating tread devices in accordance with Section 1009.9.
- - - 2. Spiral stairways in accordance with Section 1009.8.
- - - 3

. Aisle stairs in assembly seating areas where the stair pitch or slope is set, for sight line reasons, by the slope of the adjacent seating area in accordance with Section 1025.11.2.
- - - 4. 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 7.75 inches (197 mm); the minimum tread depth shall be 10 inches (254 mm); the minimum winder tread depth at the walk line shall be 10 inches (254 mm); and the minimum winder tread depth shall be 6 inches (152 mm). A nosing not less than 0.75 inch (19.1 mm) but not more than 1.25 inches (32 mm) shall be provided on stairways with solid risers where the tread depth is less than 11 inches (279 mm).
- - - 5. See the Section 3403.4 for the replacement of existing stairways.

The simple basic way to remember this is 4-7-11-3/8 for 4" minimum riser height, 7" maximum riser height, and 11" minimum tread depth. Then, as for residential stairs, the riser heights shall not vary greater than 3/8" lowest to highest, and the tread depths shall not vary greater than 3/8" narrowest to deepest (as shown below).

- 1009.3.2 Dimensional uniformity. Stair treads and risers shall be of uniform size and shape. The tolerance between the largest and smallest riser height or between the largest and smallest tread depth shall not exceed 0.375 inch (9.5 mm) in any flight of stairs. The greatest winder tread depth at the 12-inch (305 mm) walk line within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm) measured at a right angle to the tread’s leading edge.
- - Exceptions:

- - - 1. Nonuniform riser dimensions of aisle stairs complying with Section 1025.11.2.
- - - 2. Consistently shaped winders, complying with Section 1009.3, differing from rectangular treads in the same stairway flight.
- - Where the bottom or top riser adjoins a sloping public way, walkway or driveway having an established grade and serving as a landing, the bottom or top riser is permitted to be reduced along the slope to less than 4 inches (102 mm) in height, with the variation in height of the bottom or top riser not to exceed one unit vertical in 12 units horizontal (8-percent slope) of stairway width. The nosings or leading edges of treads at such nonuniform height risers shall have a distinctive marking stripe, different from any other nosing marking provided on the stair flight. The distinctive marking stripe shall be visible in descent of the stair and shall have a slip-resistant surface. Marking stripes shall have a width of at least 1 inch (25 mm) but not more than 2 inches (51 mm).

Note the "in any flight of stairs" in the above. A stairway may include more than one "flight of stairs", as a "flight of stairs" is from landing to landing whereas a "stairway" includes all "flights of stairs" and all landings.

Then there are the requirements for handrails:
- 1012.2 Height. Handrail height, measured above stair tread nosings, or finish surface of ramp slope shall be uniform, not less than 34 inches (864 mm) and not more than 38 inches (965 mm).
... and don't forget this ...
- 1012.5 Handrail extensions. Handrails shall return to a wall, guard or the walking surface or shall be continuous to the handrail of an adjacent stair flight or ramp run. At stairways where handrails are not continuous between flights, the handrails shall extend horizontally at least 12 inches (305 mm) beyond the top riser and continue to slope for the depth of one tread beyond the bottom riser. At ramps where handrails are not continuous between runs, the handrail shall extend horizontally above the landing 12 inches (305 mm) minimum beyond the top and bottom ramps.
- - Exceptions:

- - - 1. Handrails within a dwelling unit that is not required to be accessible need extend only from the top riser to the bottom riser.
- - - 2. Aisle handrails in Group A occupancies in accordance with Section 1025.13.

Then there are the guards (guardrails):
- 1013.2 Height. Guards shall form a protective barrier not less than 42 inches (1067 mm) high, measured vertically above the leading edge of the tread, adjacent walking surface or adjacent seatboard.
- - Exceptions:

- - - 1. For occupancies in Group R-3, and within individual dwelling units in occupancies in Group R-2, guards whose top rail also serves as a handrail shall have a height not less than 34 inches (864 mm) and not more than 38 inches (965 mm) measured vertically from the leading edge of the stair tread nosing.
- - - 2. The height in assembly seating areas shall be in accordance with Section 1025.14.
-

1013.3 Opening limitations. Open guards shall have balusters or ornamental patterns such that a 4-inch-diameter (102 mm) sphere cannot pass through any opening up to a height of 34 inches (864 mm). From a height of 34 inches (864 mm) to 42 inches (1067 mm) above the adjacent walking surfaces, a sphere 8 inches (203 mm) in diameter shall not pass.
- - Exceptions:

- - - 1. The triangular openings formed by the riser, tread and bottom rail at the open side of a stairway shall be of a maximum size such that a sphere of 6 inches (152 mm) in diameter cannot pass through the opening.
- - - 2. At elevated walking surfaces for access to and use of electrical, mechanical or plumbing systems or equipment, guards shall have balusters or be of solid materials such that a sphere with a diameter of 21 inches (533 mm) cannot pass through any opening.
- - - 3. In areas that are not open to the public within occupancies in Group I-3, F, H or S, balusters, horizontal intermediate rails or other construction shall not permit a sphere with a diameter of 21 inches (533 mm) to pass through any opening.
- - - 4. In assembly seating areas, guards at the end of aisles where they terminate at a fascia of boxes, balconies and galleries shall have balusters or ornamental patterns such that a 4-inch-diameter (102 mm) sphere cannot pass through any opening up to a height of 26 inches (660 mm). From a height of 26 inches (660 mm) to 42 inches (1067 mm) above the adjacent w

alking surfaces, a sphere 8 inches (203 mm) in diameter shall not pass.
- - - 5. Within individual dwelling units and sleeping units in Group R-2 and R-3 occupancies, openings for required guards on the sides of stair treads shall not allow a sphere of 4.375 inches (111 mm) to pass through.