OSHA introduced it's own minimums for tread depth and riser height in the 2017 update to walking-working surfaces. Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Stair risers must be between 4 and 7 inches high, and the depth of each step cannot be less than 11 inches. Figure D-7 -- Door or Gate Opening on Stairway. 7. Step riser specifications riser height (<= 7.75" or in some codes <= 7.0" or in Canada <=8.25") maximum and 4 inches (102 mm) minimum. and minimum tread depths of 10 in. Spiral stairs must meet the vertical clearance requirements in paragraph (d) (3) of this section. OSHA introduced minimum tread depths in its 2017 update to walking-working surface standards. A single step with a maximum riser height of 7 inches (178 mm) is permitted for buildings with occupancies in Groups F, H, R-2, R-3, S and U at exterior doors not required to be accessible by Chapter 11. 8. R311.7.5.1 Risers. IBC 1011.5.2 requires that stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. The IRC (International Residential Code) calls for a maximum rise (“ r ”) of 7 ¾â€ and a minimum run (“ R ”) of at least 10”. 504.3 Open Risers. Risers shall be 4 inches (100 mm) high minimum and 7 inches (180 mm) high maximum. Spiral, ship, or alternating tread-type stairs are used only when the employer can demonstrate that it is not feasible to provide standard stairs. OSHA will deem those stairs in compliance if they meet the dimension requirements specified in Table D-1 of this section or they use a combination that achieves the angle requirements of paragraph (c)(1) of this section. Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads. There is not a maximum stair tread depth under either the 2018 IBC stairway design criteria or the OSHA stairway design criteria. Commercial Stair Riser Height The code specifies that risers should not be more than 7 inches in height and not less than 4 inches when measured vertically between the nosing of the adjacent tread. All steps on a flight of stairs shall have uniform riser heights and uniform tread depths. OSHA and IBC also have different maximum stair riser height requirements depending on the type of stairway. Figure D-10 -- Angles for Stairs, Ramps, and Ladders. Vertical clearance above any stair tread to any overhead obstruction is at least 6 feet, 8 inches (203 cm), as measured from the leading edge of the tread. The stair riser height code is also defined in OSHA sections 1910.21 and 1910.25 and in IBC chapter 10 means of egress. (d) Winders shall not be permitted in stairs required as … Stairs shall comply with 504. OSHA 1910.25(d)(2) requires spiral stairs to have have a maximum riser height of 9.5 inches (24 cm). Have a maximum riser height of 9.5 inches (24 cm); 1910.25(d)(3) Have a minimum headroom above spiral stair treads of at least 6 feet, 6 inches (2 m), measured from the leading edge of the tread; IBC has required minimum tread depth for many years. OSHA 1910.21 defines a stair riser as the upright (vertical) or inclined member of a stair that is located at the back of a stair tread or platform and connects close to the front edge of the next higher tread, platform, or landing. A riser is the vertical part of the stair that joins one step or tread to another. Under OSHA, a standard stair means a fixed or permanently installed stairway that is not an alternating tread stair, ship stair, or spiral stair. You can see from the chart that the minimum tread depth and maximum riser heights vary greatly between different stair types. The Codes (2009 IRC): 311.7.1 – Stairways shall be a minimum of 36” wide; 311.7.4.1 – Maximum Riser Height is 7 ¾â€ (max. Notes to Table 9.8.4.1.: (1) service stairs are stairs that serve areas used only as service rooms or service spaces and stairs that serve mezzanines not exceeding 20 m 2 within live/work units. The codes only state a maximum riser height of 7-3/4”. [39 FR 23502, June 27, 1974, as amended at 43 FR 49744, Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984; 81 FR 82987-82990, Nov. 18, 2016; 84 FR 68795, Dec. 17, 2019], Occupational Safety & Health Administration. For the purpose of this section, all dimensions are exclusive of carpets, rugs or runners. The standard riser is the. OSHA 1910.25(f)(3) requires alternating tread stairs to h. (ship ladder) as a stairway that is equipped with treads, stair rails, and open risers, and has a slope that is between 50 and 70 degrees from the horizontal. The standard riser is the vertical member of a stair that is located at the back of a stair tread and connects close to the front edge of the next higher tread. The risers shall be sufficient to provide a headroom clearance of 78 inches (1981mm) minimum. 1. FIGURE D-8 — Dimensions of Standard Stairs. 1011.5 Stair treads and risers. The greatest riser height within any flight of stairs must not exceed the smallest by more than three-eighths inch. The riser shall be measured vertically between leading edges of the adjacent treads. Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. (B) The minimum tread depth is 9 inches measured from tread nosing to tread nosing. 2. Stair tread depths shall be 11 inches (279 mm) minimum. R311.5.3.1 Riser height. Open risers are not permitted. The riser measurements must be equal across an entire flight of … The section of a stairway leading from one landing to the next is a flight of stairs. International Residential Code for Stair treads and risers R311.5.3 Stair treads and risers. This means your stair … The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch. a height of between 34 and 38 inches above the nosing. The maximum riser height shall be 8.25 inches (210 mm). JUMP TO FULL CODE CHAPTER Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Have a minimum width of 22 inches (56 cm) between vertical barriers (see Figure D-8 of this section). R311.5.3.1 Stair Riser Height Codes. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3 / 8 inch (9.5 mm). Under OSHA 1910.21 the stair tread means a horizontal member of a stair or stairway, but does not include landings or platforms. Understanding the requirements can help ensure your stairs are safe and in compliance with OSHA and IBC. Are installed at angles between 30 to 50 degrees from the horizontal; Have a maximum riser height of 9.5 inches (24 cm); Have a minimum tread depth of 9.5 inches (24 cm); and. For treads and riser of alternating tread stairs, OSHA requires that alternating tread stairs have a series of treads installed at a slope of 50 to 70 degrees from the horizontal and that they have a minimum tread depth of 8.5 inches (22 cm). Table D-1 -- Stairway Rise and Tread Dimensions. There are only minimum stair tread depth requirements. OSHA 1910.25(e)(3) requires ship stairs to h, 1910.25(c)(2) requires standard stairs to h, Alternating Stair Riser Height Requirements, OSHA 1910.25(e)(2) requires ship stairs to h, You can see from the chart that the minimum tread depth and maximum riser heights vary greatly between different stair types. When paragraph (b)(8) of this section allows the use of spiral, ship, or alternating tread-type stairs, they are installed, used, and maintained in accordance with manufacturer's instructions. OSHA and IBC have different tread depth requirements for different stair types. Have open risers if the tread depth is less than 9.5 inches (24 cm); Occupational Safety and Health Administration, Severe Storm and Flood Recovery Assistance. Staircase Width: 36 Inches, Minimum. The maximum riser height shall be 8 1 / 4 inches (209 mm). shall be permitted in new construction. Stairs shall not have a variation exceeding 3/16 inch in the depth of adjacent treads or in the height of adjacent risers. The requirements of paragraphs (c)(2) and (3) do not apply to standard stairs installed prior to January 17, 2017. OSHA 1910.25(c)(3) requires standard stairs to have a minimum tread depth of 9.5 inches (24 cm). vertical member of a stair that is located at the back of a stair tread and connects close to the front edge of the next higher tread. Based on these results and others,  the major building codes adopted standards for minimum tread depth and riser heights. OSHA defines a Ship stair (ship ladder) as a stairway that is equipped with treads, stair rails, and open risers, and has a slope that is between 50 and 70 degrees from the horizontal. The tolerance between the largest and smallest riser, or between the largest and smallest tread, shall not exceed 3/8 inch in any flight of stairs. OSHA defines a Spiral stair as a series of treads attached to a vertical pole in a winding fashion, usually within a cylindrical space. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). OSHA does not state specifically a maximum riser height for alternating tread stairs. Any variation of risers within a flight of stairs should not be more than ⅜ inch of tolerance. Based on the stair codes and safety research, we recommend designing stairs to maximize stair tread depth as much as possible. The riser shall be measured vertically between leading edges of the adjacent treads. R311.7.5.1 Riser height. Buildings codes have been created to control the minimum and maximum measurements of risers and treads. Stairs with a total rise of more than 30" are permitted to have open risers provided that the opening between treads does not permit the passage of a 4-inch diameter sphere. IBC 2018 states that "tread depth is 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 Michigan Residential Building Code specifies that a riser be a maximum height of 8.25 inches as measured vertically between the leading edges of the adjacent treads. © 2020 Lapeyre Stair Inc. All rights reserved. IBC 1011.10 requires that spiral stair riser height shall not be more than 9 1/2 inches (241 mm). 504.2 Treads and Risers. (2) Private stairs are interior stairs within dwelling units and exterior stairs serving a single dwelling unit or a garage that serves a single dwelling unit. IBC 1011.5.2 requires that stair treads be 11 inches (279mm) minimum measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the treads leading edge. The riser height shall be measured … See the following drawing for required handrails. International Building Code for Stair treads and risers 1009.3 Stair treads and risers. With as close as possible tread depth codes and it is to be measured between... 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