What is the standard depth of a stair tread?
The general rule (in the US) is 7-11 (a 7 inch rise and 11 inch run). More exactly, no more than 7 3/4 inches for the riser (vertical) and a minimum of 10 inches for the tread (horizontal or step). You can find some more information here as well on other stair-related dimensions.
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). R318.104.22.168 Tread depth. The minimum tread depth shall be 10 inches (254 mm).
- A nosing is not required where the tread depth is a minimum of 11 inches (279 mm). The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less.
- To get to your question - the code doesn't refer to the exterior in steps but states from finished floor or platform to finished grade in excess of 30" requires a guard rail. It's with interior they mention any stairway with more than 3 risers (2 steps) will require a handrail.
- The angle is based on the amount of space available, but is commonly determined by the rise and run of a stair. With a 7 inch riser and an 11 inch tread (this is usually a minimum) you get an angle of arctan(7/11) or 32 degrees.
As you may have noted from the sketches and text above, typically building codes for stairs specify minimum stair tread thickness (1" if supported by a riser at front, or 1 1/2" thick treads if the stairs are open-construction without risers), but they do not specify a maximum allowable tread thickness.
- Treads and risers install should start at the bottom step. First the riser and then the tread. However, on the tread you leave a 1/4 inch gap on the back edge and then install the next riser. Your riser should be at least 1/2" thick and the tread no less than 1" thick.
- ADA Hallway Width. Hallways in public buildings must provide an adequate amount of space to conveniently accommodate people in wheelchairs. The minimum required ADA hallway width is 36 inches. The standard commercial hallway width is also 36 inches, to account for ADA standards.
- The minimum corridor width shall be as determined in Section 1005.1, but not less than 44 inches (1118 mm). Exceptions: 1. Twenty-four inches (610 mm)—For access to and utilization of electrical, mechanical or plumbing systems or equipment.
Other than being a necessary part of the structure of a staircase, does stair nosing serve any other purposes? The main purpose of a nosing is to improve the safety of the staircase. As it protrudes a little over the edge of the tread, it provides some extra space for users to place their feet.
- A stair flight is a run of stairs or steps between landings. A staircase or stairway is one or more flights of stairs leading from one floor to another, and includes landings, newel posts, handrails, balustrades and additional parts.
- A stair tread is the horizontal portion of a set of stairs on which a person walks. The tread can be composed of wood, metal, plastic, or other materials. In residential settings, treads can be covered in carpeting. Stair treads can come in non-slip varieties, particularly in commercial or industrial locations.
- Reducer moldings are used when two floors of slightly different thicknesses come together, such as a laminate floor and a wood, vinyl, ceramic or low-pile carpet floor. For floor transitions of more extreme, unequal height differences, you'll need to use an end molding.
Updated: 26th October 2019