discrepancy is allowed) The reason for the codes? Maximum 12 feet vertical height (rise) for a flight of stairs. With the above example we had to calculate the stair width, but with this exception you can have the stairway width be as small as 36 inches as long as the occupant load it is serving is less than 50. Remember when it was said that the minimum width of a stairway shall not be less than 44 inches? Since we are talking about exceptions, let us go back and take a look at Section 1011. The problem however is that with 7-3/4" risers the formula would allow 9" treads. The stair tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at right angle to the tread’s leading edge. Stair dimensions in all three common codes, the OSHA codes for workplaces and the IBC and IBC-derived codes for residences and commercial buildings are complicated. Stair Tread and Nosing Design Parameters. The width of the landing must not be less than the width of the stairs it serves. 1910.25(b)(3) 7). It is also the approach space at the top and bottom of the stairs. Handrails are required on both sides of a stairway. 200 occupants x 0.3 inch per occupant = 60 inches. Historically, all of the stair parts and components were typically made of whatever material was consistent with the rest of the building such as stone, wood, or masonry. (utility stairs, stairs to access mechanical systems, etc), Step tread depth uniformity (<= 3/8″ variation), Stair tread depth for winder stairs (>= 6″ at smallest point), Stair tread uniformity for winder stairs at the 12″ walk-line (<= 3/8″ variation), Stair tread slope (out of level on walking surface) – (slope or “rise” must be <= 1 in 48). Minimum width for stairways is determined by using a factor of 0.3 inch per occupant for non-sprinklered buildings or a factor of 0.2 inch per occupant for buildings equip with sprinklers and alarms, but shall at no point be less than 44 inches. The provisions for existing buildings in Chapter 34 are based on the 2018 International Existing Building Code (IEBC). Commercial stairways must have a floor or landing located at both the top and bottom of the stairs. The code lists specifications for width and height of stair tread. D2.13. Spiral stairs must meet the vertical clearance requirements in paragraph (d)(3) of this section. The run should be between 210 mm (8 ¼”) and 355mm (14”). (Title 24, Part 2, Section 3305(a).) Exception 1 in Section 1011.2 allows for a width of not less than 36 inches when a stairway is serving an occupant load of less than 50. A lot of condo builders use 7-3/4" / 10" which I find uncomfortably steep. Stairways have to be at least 44″ (1118mm) if occupant load is over 50 and 36″ (914mm) width if under 50 occupants you can go to. Minimum stair diameter of 60" for a metal stair and 64" for a wood stair; Tread path between handrail and center column a minimum 26" Center tread width, 7 1/2" in from the narrow end of the tread d; Headroom minimum of 6'6" Riser height cannot exceed 9 1/2" Building Codes for Stair Tread Nosing in Staircase Specifications, https://inspectapedia.com/Stairs/Stair_Codes_Rules.php, Step riser specifications riser height (<= 7.75″), Step riser height uniformity (<= 3/8″ variation), 1009.3.1 Dimensional uniformity. Stairs cannot be continuous without have a landing or floor level that breaks up the flight of stairs. This is measured from top of a tread nosing to the top of the next tread nosing or landing. Each locale can require different measurements for the length, tread and rise of the stairs so be sure to check with your local government authority. DESIGNS Concrete Stairs Designs vary depending on the product. (i) Riser height and tread depth must be uniform within each flight of stairs, including any foundation structure used as one or more treads of the stairs. 4.5 Stair winders 33 4.6 Visibility of stair treads 33 5.0 Fixed Ladders 34 5.1 General 34 5.2 Step-type ladders 37 5.3 Rung-type ladders 38 5.4 Individual rung-type ladders 39 6.0 Handrails 39 Page 7.0 Doors and openings 43 8.0 Places of Assembly 43 8.1 Spaces … Winder treads shall have a minimum tread depth of 11 inches (279 mm) between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline and a minimum tread depth of 10 inches (254 mm) within the clear width of the stair. landings should not cause danger of slipping. This is a measurement from the nose of the tread to nose of the tread. Several components are looked at such as stair width, headroom, riser and tread heights. The Ontario Building Code | Treads and Risers 3.4.6.8. In this post we will be looking at the code standards related to commercial stairs in accordance with the International Building Code (IBC). Florida Building Code, Residential. International Building Code Guidelines overview for commercial buildings and common stairs in buildings.It is much more complex, but these are the general rules. A uniform flight of stairs provides a safety factor. Steps and stairways have been constructed out of many different materials and in many different construction assemblies. Be sure to check out this POST.eval(ez_write_tag([[300,250],'buildingcodetrainer_com-box-3','ezslot_4',106,'0','0'])); Looking for Residential Stair Requirements? After seeing the popularity of my post on Residential Stair Design, I thought it made sense to explain the guidelines from the 2006 International Building Code for commercial buildings and common stairs in buildings with more than two dwelling units.It is much more complex and there are some exceptions if you need them so please contact me if you need help. Therefore limitations in riser heights and minimum widths for treads is an important rule to follow.eval(ez_write_tag([[728,90],'buildingcodetrainer_com-leader-1','ezslot_7',112,'0','0'])); 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. The tolerance between the largest and smallest riser or between the largest and smallest tread shall not exceed 0.375 inch (9.5 mm) in any flight of stairs. Stairways serving an occupant load of less than 50 shall not be less than 36 inches in width. 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