Stair dimensions (C) Carson Dunlop Associates Stair step height: Guide to Stair Riser Dimensions

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Stair riser specifications:

This article provides building code specifications, sketches, photographs, and examples of the proper stair step height or stair riser dimensions and other stair riser requirements for indoor or outdoor stairways. We compare the code requirements for closed riser and open riser stairs and we include other basic stair tread and riser dimensions.

Topics here include Allowable variation in stair step riser height by code & to avoid tripping. Definition of & specifications for open riser & closed riser stairs. Suggestions for adapting pre-fabricated stairways to the to the actual overall stairway height without violating building stair codes & standards.

Basic stair riser height dimensions required for safe stairs. Different dimensions for open versus closed riser stairways. Stair safety hazards, photos of defects & Sketches of stair design requirements. Stair calculations: how to calculate custom stair tread & risers based on stair rise & run measurements.

We also discuss the allowable variation in stair or step riser height between individual steps in a stairway. Sketch at page top courtesy Carson Dunlop Associates.

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Stair Riser Dimensions, Specifications, Codes, Standards & Defects

Undersized stair tread depth (C) Daniel Friedman

Stair risers are detailed here. For a complete list of articles on stairs, railings, and ramps, their inspection, trip hazards, and good design,
see STAIRS, RAILINGS, LANDINGS, RAMPS - INSPECTIONS, CODES. Or see these detailed articles on specifications for proper dimensions for stairs, railings, platforms

Because more people are injured by trips and falls than other hazards, experts have looked closely at the specifications for stairs, steps, and rails to reduce the falling hazards.

This work has been translated into stair and railing specifications that are similar among codes and countries (but not identical). -- IBC, IRC, BOCA, Kingston NY Stair Code, & other sources.

Definition of stair risers (stair riser height)

A stair riser (green arrow in our photo at above left) is the vertical distance (green arrow) between the walking surface of two stair treads (treads are what you step on) is the stair riser or riser height.

Stair riser heights The riser height shall be measured vertically between the leading edges of adjacent treads.

Stair treads: The stair tread is the horizontal walking surface (red arrow) of an individual step. The tread depth is measured from the forward edge of the step nose or edge of the step above out to the leading edge of the step being measured - the space beneath my foot in the photo at left.

Stair tread depths shall be 11 inches (279 mm) minimum.

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.

Details about stair treads are found at STAIR TREAD DIMENSIONS


Definition of & Detailed Specifications for Closed Riser Stairs

Closed Riser Stairs demo by Quinn Morgan GilliganClosed riser stairs (demonstrated at left by the author's granddaughter Quinn Morgan Gilligan) include a vertical riser board (that my toe is kicking against). Stair risers are detailed at STAIR RISER SPECIFICATIONS. Photo by permission.

Don't confuse step riser height (defined above) with stairway headroom - the vertical space between the walking surface of a stair tread and the ceiling or other obstruction overhead (defined further at STAIR HEADROOM).

If the vertical space is enclosed (see our Carson Dunlop sketch above), the enclosing board is called the stair riser.

Summarizing proper stair dimensions for Closed Riser Stairs

Closed riser stairs include a board or other solid material that encloses the vertical space between stair treads.

Definition of & Detailed Specifications for Open Riser Stairs

Stair dimensions (C) Carson Dunlop AssociatesIf the vertical space between stair treads is open (see our photo at left) the space is still a stair riser, but it's an "open riser".

Or simply put, open riser stairs have no enclosure (my toe, shown above would be facing into open space).

Open stair risers with a more than 4-inch opening are a child hazard, as we detail below.

Summarizing proper stair dimensions for Open Riser Stairs

Open riser stairs (shown at right in the sketch above) do not include a solid board or other material that fully encloses the open space between stair treads.

Are These Stairs Open Riser or Closed Riser Design?

Closed riser stairs Maria Mitchell Observatory Vassar College (C) Daniel Friedman

The lovely stairway shown at left rises to the main entry for the Maria Mitchell Observatory on the Vassar College Campus, Poughkeepsie, New York.

But are these open risers or closed riser stairs?

They are closed riser stairs (except for that broken missing riser at the first step) because the cast iron gridwork defines the limits of placement of the leading toe of a foot of someone ascending these steps.

Therefore the rules for stair nose design and projection apply to these steps.

Stair Riser Defects in Height, Slope, Consistency

Quick Summary of Stair Riser or Height Hazards

As we explained above, the most common stair riser defects likely to lead to a fall include:

Unsafe Deck, Deck Stairs & Deck & Stair Railing Example

Unsafe exterior stair stringer and riser height (C) Daniel FriedmanNothing is right about the exterior stairs shown in our photo (at left ) from a 1991 home inspection:

See DECK STAIR BUILDING START for more details.

Stair Riser Height for Seniors & People with Limited Stair Climbing Ability

Reader Question: 28 April 2015 Cynthia Johnson said:

What are the best dimensions for seniors with physical limitations i.e. Rheumatoid Arthritis?


Experts suggest that for more physically limited people the best way avoid falls is to seek living accomodations on a single floor.

Affi et als (2014 and earlier) have weighted the contributions of various stair features to the risk of a stair fall, considering for example, straight versus turned stairways, with or without landings, number of steps, handraiil design, lighting specifications, and step design specifications (using a tread depth of 269mm and a riser height of 174mm with a 40 mm tread nosing in a case example to state various risk contributors.

Please see complete details at STAIR DESIGN for SENIORS


Continue reading at STAIR TREAD DIMENSIONS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see STAIR RISER HEIGHT FAQs questions & answers posted originally on this page.


Suggested citation for this web page

STAIR RISER SPECIFICATIONS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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