The riser height must be between 4″ and 7″ and the treads must be at least 11″ deep. We would like to do something striking and beautiful with a winding stairs but I am confused about the requirement in 1009.11 that says the smallest radius must be twice the minimum width. 1012.2 Height. There are already several set of fire stairs in the building which provide adequate egress. Jill. 27a. Bill, with a strict reading of the code, the 44″ should be a clear width, so the carpet made it too narrow. Now when … The stair tread is the horizontal portion of the staircase on which people walk, the stair riser is the vertical portion of the staircase between each tread. What is a stair treadand stair riser? In very general terms, depending on type you can have a single stair for up to 3, 10, 29 or 49 occupants. There are other exceptions for spiral stairs, aisle stairs and incline stairs but these types will have to be covered in a later post. But, this rule includes a phrase that states that its only for the required width. Again the tolerance between treads should be no more than ⅜ inch. Stair details refer to the standard requirements for each of the various components of a flight of stairs. It aligns with the IBC by requiring the handrail to extend only one tread depth at the bottom of the stair. For the purposes of this section all dimensions and dimensioned surfaces shall be exclusive of carpets, rugs or runners. That allows projections of up to 4.5″ at or below the handrail height and also above the headroom requirement. Thanks for the info. Also, does one need to worry about the use of an exterior metal staircase during lightning? Utility (Public) = … The tread depth (TD) is to be ≥ 185mm and it should not be more than 30mm shorter than the going (G). If under 50 occupants you can go to 36″ width. Use our Size Comparison calculator to compare the dimensional properties of Risers & Treads with other related elements from our database. That being said the tread depth is a minimum, it can always be larger. Space : 24" to the left, right, and front of the Tread … Weight: 455 lb. Landing width shall not be less than the required staircase width. 5335 West 48th Ave Suite 300Denver, CO 80212. Where you measure the width is not called out in a really obvious way, but in the handrail section of the 2006 IBC it is under 1012.7. As general rules of thumb for achieving comfortable relationships between riser and tread dimensions, the following formulas can be used: ‍ Tread (inches) + 2x Riser (inches) = 24”-25” (26” for exterior stairs) Riser (inches) x Tread (inches) = 72”-75” The riser height must be between 4″ and 7″ and the treads must be at least 11″ deep. Regulated by building codes, stair details specify the sizes of risers and treads, stair widths, the placement of handrails and guardrails, and construction methods for fabricating stairs. So 14 risers of 7″ height is only 98″. Treads-Risers-Total Wood Volume: 0. When using 1/4" bearing bars, Stair Tread widths are 1/16" more. Staircase width refers to the side-to-side distance if you were … At this moment we have a 3 ft stair case and we were told that it’s not wide enough that we must have atleaste 2 staircases 4ft wide. Hi Sean, Stairways guardrail and handrails Uniform Dimensions (IBC 1011.5.4) (Plus, ErectaStep’s stairs go above and beyond with a wider width and longer tread than the OSHA minimum – read more about our product specs here.) Staircase Width: 36 Inches, Minimum. If you have winders they need to be at least 11″ deep when you’re 12″ in from the narrow edge and the minimum depth must be 10″. If so , can you tell me where I can find this code requirement? EVstudio is a full-service in-house design firm specializing in architecture, engineering, planning, and other design services for commercial and residential projects. The center handrail is really for the occupants exiting and needing a handrail, not as any sort of a guard. Savas, I’ll assume this is the International Building Code. Responding to the movement of the human body, the sizes and relationships of stair risers and treads are regulated to make vertical motion safe and easy. I understand we are exempt from building regulations but there must be some standards which need to be complied with? Whether you're adding or revising stairs to a workplace or your office or home, this is an area where a … If so, the step won’t work. 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. Scaled 2D drawings and 3D models available for download. This is definitely the realm of a competent architect. I haven’t heard concerns about exterior metal stairs and lightning but if it is a prominent feature it could happen. Open risers are not permitted. A confirmation email has been sent. Two pipe railings are only acceptable in certain occupancies with low numbers of occupants, generally you need the 4″ spacing where you are over 30″ high. Key dimensions for the risers and goings of stairs are outlined in this table: Additionally, the tread depth must be greater than or equal to 185mm. Table D-1 — Stairway Rise and Tread Dimensions Minimum tread width 22 IN (56 CM), Minimum Tread Depth 9.5 IN (24 CM), Maximum Riser Height 9.5 IN (24 CM). If so, what are the rules, etc? 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. You also have step-light options placing the light only a foot or so above the treads. Most commercial buildings will also require the ramp design guidelines. The maximum riser height shall be 7 … This stair will be purely an aesthetic feature and for convenience of the staff and visitors. So 15″ or 12″ are both acceptable. Is this an IBC code? Private Staircase(Domestic) = 42° Maximum. Stairways have to be at least 44″ if you have an occupant load over 50 (and may be more if your occupant load is large). Stair treads and stair risers can be made of a variety of materials with treads often having a partial or total surface with some non-slip properties for safe egress.