New stairs commercial and residential . . .

[LindaDeavers]

I asked a question earlier this week and I haven't heard from you yet. Hopefully it will be soon.

Here's another question. My boss just called and asked me to check the nationwide BOCA for riser height and tread width. I would like to know what it is or how to find it.

Thank you.

[Jerry Peck - Codeman]

Hi Linda,

I asked a question earlier this week and I haven't heard from you yet. Hopefully it will be soon.

The answer was posted here ( viewtopic.php?f=13&t=230 ) the same day you asked your question.

My boss just called and asked me to check the nationwide BOCA for riser height and tread width. I would like to know what it is or how to find it.

By "nationwide BOCA" code I suspect he is referring to the ICC IRC, which was based on the old BOCA One- and Two Family Building Code.

Keep in mind what my other answer to your other question pointed out - that the old BOCA code and the IRC are not applicable to commercial buildings, only one- and two family dwellings and townhouses. (underlining and bold are mine)
- The 2006 IRC states:
- - R311.5 Stairways.
- - - R311.5.1Width. Stairways shall not be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. Handrails shall not project more than 4.5 inches (114 mm) on either side of the stairway and the minimum clear width of the stairway at and below the handrail height, including treads and landings, shall not be less than 31.5 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are provided on both sides.
- - - - Exception: The width of spiral stairways shall be in accordance with Section R311.5.8.
- - - R311.5.2 Headroom. The minimum headroom in all parts of the stairway shall not be less than 6 feet 8 inches (2036 mm) measured vertically from the sloped plane adjoining the tread nosing or from the floor surface of the landing or platform.
- - - R311.5.3 Stair treads and risers.
- - - - R311.5.3.1 Riser height. The maximum riser height shall be 7-3/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).
- - - - R311.5.3.2 Tread depth. The minimum tread depth shall be 10 inches (254 mm). 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. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Winder treads shall have a minimum tread depth of 10 inches (254 mm) measured as above at a point 12 inches (305 mm) from the side where the treads are narrower. Winder treads shall have a minimum tread depth of 6 inches (152 mm) at any point. Within any flight of stairs, the largest winder tread depth at the 12 inch (305 mm) walk line shall not exceed the smallest by more than 3/8 inch (9.5 mm).
- - - - R311.5.3.3 Profile. The radius of curvature at the leading edge of the tread shall be no greater than 9/16 inch (14 mm). A nosing not less than 3/4 inch (19 mm) but not more than 11/4 inch (32 mm) shall be provided on stairways with solid risers. The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings. Beveling of nosing shall not exceed 1/2 inch (12.7 mm). Risers shall be vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted, provided that the opening between treads does not permit the passage of a 4-inch diameter (102 mm) sphere.
- - - - - Exceptions:
- - - - - - 1. A nosing is not required where the tread depth is a minimum of 11 inches (279 mm).
- - - - - - 2. The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less.