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

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 of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Stair Riser Dimensions, Specifications, Codes, Standards & Defects

Undersized stair tread depth (C) Daniel Friedman

Stair risers are detailed here.

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 (marked in yellow in our photo) is the vertical distance between the walking surface of two stair treads (treads are what you step on) - also referred to as the stair riser or riser height.

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

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

Headroom is defined further at STAIR HEADROOM.

The stair tread or run is the horizontal walking surface (red arrow in our photo above) of an individual step. It should be no less than 10". (IRC)

The stair tread depth, also referred to as the step "run" or horizontal distance in the direction of travel, 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 shown above.

Definition of 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 enclose the space between the stair treads ) or walking surfaces.

In the photo, our yellow arrow points to the step riser and the white arrow points to the stair tread.

The photo includes an unsafe bottom stair riser that is significantly different in height than the rest of the risers in that entry.

If the vertical space is enclosed (see our Carson Dunlop sketch at the top of this page), the enclosing board is called the stair riser.

The trip and fall hazard caused by stairs whose steps are uneven in height (rise) has been known probably for thousands of years as one discovers it promptly when using uneven-rise stairs without paying close attention to the step height.

While most false-step stair hazards are constructed in error, in some structures, stair builders deliberately created a so-called false-step as a security measure against intruders.

See FALSE STEP STAIRS found

in SLIP TRIP & FALL HAZARD LIST, STAIRS, FLOORS, WALKS for details

 

Summary of Ideal Stair Dimensions for Closed Riser Stairs

Marble stairway Mexico City Post Office (C) Daniel Friedman at InspectApedia.comThis beautiful stairway is in the old central Post Office building in Mexico City.

The marble stair treads are a bit slippery and there is no handrailing along the lower rounded steps, but the tread dimensions are correct and comfortable.

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

Details are at STAIR TREAD DIMENSIONS

 

Definition of 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.

Step stair riser openings:

open stair risers are permitted provided the opening will not pass a 4" sphere (child safety). This 4-inch opening dimension has the same basis as the rule that requires that the opening between stair balusters must be 4" or smaller.

Unsafe open riser stairs (C) Daniel Friedman at InspectApedia.com

Photo above: notice that these stairs are built with an excessive "back slope" - there is more than 1 1/2" opening between the back edge of the lower stair tread (under my foot) and the leading edge of the upper tread.

Too-Short-Run Under-Sized Treads Cause of Unsafe Open Riser Stairs

Watch out: As my foot illustrated in the photo below, we often find open riser stairs that are unsafe because the tread inner edge does not extend beneath the outer edge of the tread above - excessive stair step or tread riser "back slope" as we defined it above.

Open riser stair treads are unsafe if treads are not properly aligned, leaving open walking space (C) Daniel Friedman Lourdes Mexico at InspectApedia.com

Where there are several inches of open space at the inside edge of a stair tread someone, particularly a child with small feet, could easily step into this space, risking serious injury.

These stair treads, at a restaurant in San Miguel de Allende, Guanajuato, Mexico, are also too short in depth, less than 10" and so are under-sized.

If the builder had simply made each stair tread 2" greater in depth or run, both of these stair fall hazards would have been avoided.

Unsafe open riser stairs (C) Daniel Friedman at InspectApedia.com

Someone may have fallen into these stairs because several years after I took the photo above I found that the property owners had added a filler across the open space at the inside edge of the 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?

These are closed riser stairs (except for that broken missing riser at the first step) because the cast iron grid work 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

Remarkable stairway in Oxaca (C) Daniel Friedman at InspectApedia.comI'm not sure what to say about this remarkable stairway found in Oxaca.

Perhaps at night or in dim light, someone walking near the center of these steps is going to go sailing. Reader comments are invited.

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:

These Deck Stairs Combine Nearly Every Stair Mistake

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:

  1. This stair stringer is too-deeply notched and could split;
  2. The open stair risers are too high, as our client is showing with our tape.
  3. The step rise is not consistent from top to bottom, with a taller rise at the bottom step
  4. The stair treads are too narrow - short depth or too-short stair tread "run"
  5. There is no stair guard rail and
  6. There is no hand railing at all along these stairs (and the height above ground is more than 36" which means that in just about every jurisdiction stair railings would be required by the building code)
  7. The deck and platform railing is open with no balusters.
  8. The stair treads are installed "upside down" with the cupped side up so that the treads retain water, encourage algae growth, and in freezing climates, encourage ice formation
  9. The stair stringers are poorly-secured to the deck rim joist, risking stair collapse
  10. There is no landing platform that might have corrected for the extra rise at that bottom step.

About the only stair mistake missing from these wonderful deck "stairs" we found at a home inspection is the error of excessive back-slope of the open risers.

See DECK STAIR BUILDING START for more details.

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-04-16 by (mod) - very tall-riser stairs have a long history in Mexico

@Carolyn Wagstaff,

Thank you for a helpful question about building codes and stair codes and tall step riser height in Mexico.

I don't know what local officials in Algodones (Vicente Guerrero) Mexico have to say about step height, but in general, even where there are building codes they're not usually enforced to the level of detail of stair design.

In Guanajuato my experience is that a principal concern of building officials is to assure that owners don't build above a permitted height nor violate other more-general guidelines such as intruding on neighbors privacy.

[Click to enlarge any image]

I've been and documenting steps and stairs and their handrails and guardrails in Mexico since 1960, so I appreciate that you're quite right that there are plenty of tall risers and other step details throughout the country that can be a trip hazard.

"93% of Mexico’s municipalities have no construction regulations, ... They're not much more than administrative formalities anyway, says disaster prevention official" - Mexico City Daily News, September 19, 2018, available online at https://mexiconewsdaily.com/news/93-of-mexicos-municipalities-have-no-construction-regulations/

The history of tolerance of tall-rise steps goes back over a thousand years. It is mere subjective opinion, but it has always seemed to me that if I were directing the construction of a pyramid - Mexico's tallest flights of stairs - and as I considered the time and effort to bring up the materials to each of those higher stairs, I'd have made the step rise as high as people could manage.

The example I illustrate below is from Palenque in Chiapas, in 2019.

For other readers, Palenque was an important Maya city which flourished between c. 600 and 750 CE. The name Palenque derives from the Spanish, meaning 'fortified place', but the original Maya name was Lakamha.

In some cites, particularly Mexico City, where officials are acutely aware of earthquake damage hazards, building construction regulation has focused first on earthquake -resistant construction.

You'll see that "stairs" or "stair codes" do not figure in this analysis.

While the Palenque pyramids are not as tall as the Pyramid del Sol (Pyramid of the Sun, 234 feet tall, is the largest building in Teotihuacan, and one of the largest in Mesoamerica. It is believed to have been constructed about 200 AD.)

you can see that high flights of tall-riser steps have a long history.

Palenque pyramid stairs have tall risers - Chiapas Mexico (C) Daniel Friedman at InspectApedia.com

And while I've photographed and measured modern stairs and rails in Mexico, I'm still enchanted by the big pyramids. This view *down* steps from the Pyramid del sol (2011) show how daunting it can be, and even more difficult, to climb down such steep rise steps than to climb up them,



Finally, here's a photo of a tourist atop the Sun Pyramid, giving an idea of the scale of these structures.

Sun Pyraid Moon Pyramid step height and pyramid heights, Mexico City (C) Daniel Friedman at InspectApedia.com

On 2021-04-16 by Carolyn Wagstaff - stair step height was taller in Algodones, MX than in the United States

It seemed that the stair step height was taller in Algodones, MX than in the United States. Or is there no standard step height in Mexico?

On 2020-11-28 by (mod) - reader does not like the curved Oxaca Concrete stairway ?

Remarkable stairway in Oxaca (C) Daniel Friedman at InspectApedia.comFloyd

Thank you for that remarkable comment. If you have a photo of the stairs you're describing you can use the add image button to let us see that.

One photo per comment but as many comments as you need if you have more than one photo.

My OPINION

is that while stair construction is not particularly regulated in Mexico nor in quite a few other communities, at least for the curved treads we see on the Oxaca stairs, if the builder had included a pair of center handrails that'd reduce the tendency to step into the most-dangerous part of the steps.

One difference between the U.S. and Mexico's response to stair and other trip hazards is that in the U.S. we are habituated to expect the government to protect us from hazards and to expect or lawyer to get us some money if we fall down the stairs.

In Mexico people know that they might fall down the stairs and that nobody is likely to pay their medical bills for them, so they are, perhaps, a bit more-attentive and more-careful.

On 2020-11-28 by Floyd Boyd

The Oxaca Concrete stairway is a one of a kind , Expensive Colored concrete Stairway , I set form*s and poured concrete on Hotels , Resorts , Even the test range in Nevada , All within the western US states , A Commercial set of stairs like this , Done in ( US ) Would be broken into pieces , Loaded in a dump truck and hauled to the dump .

I don*t really understand why anyone with the skills it took to build these steps , Didn*t know any better . The Guy who poured the concrete made it look ok , And had to of known better , I do live in the Country with the highest standards though , And for that I thank my lucky stars .

On 2022-12-01 by InspectApedia (mod) - New York stair & railing codes

@sl,

See more of U.S. Stair Codes at

STAIR & RAILING CODES & STANDARDS

from where this is New York code is taken:

R311.5.3.1 Stair Riser Height Codes
The maximum riser height shall be 8 1 / 4 inches (209 mm). 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).

On 2022-12-01 by sl

what is the max riser in n.y 7'' or 7 3/4'' or 8 1/4''

On 2022-07-28 by InspectApedia-911 (mod) - what are "openings between braces" ?

@Olivia,

We'll be glad to help but I'm sorry to say I don't understand the question.

What are "openings between braces" ?

Are you talking about open risers (the vertical board between individual steps) ?

or about some aspect of the stair guard railing?

Or something else?

Openings in those areas are permitted and safe though there are opening size limitations between balusters in guardrails (4")

On 2022-07-28 by Olivia

I'm 74 and have to climb 20 stairs up and down with openings between braces. how dangerous is this?

On 2022-04-26 by Inspectapedia Com Moderator - how many risers do I need?

@Rich,

We give the step by step calculations at

STAIR RISE & RUN CALCULATIONS

basically total rise / 7" gives number of risers - then you pick an actual riser height that will make all of the risers identical.

15/7 = 2.14 risers so we want 2 risers.

How tall?

15 / 2 = 7.5 so we'd make 2 steps of 7.5" rise

OR we could make deeper treads and go to 3 steps:

15 / 3 = 5 - 3 5-inch risers; but IMO a 5" rise is a bit low for comfortable stair climbing unless you make your stair tread depth wider.

On 2022-04-26 by Rich

I need to build a step that is 15 in high from my house to my deck how many risers do I need?

On 2021-07-18 by inspectapedia.com.moderator

@Kade Soprano,

Thank you; your questions helped me edit and clean up this article; working together makes us smarter.

On 2021-07-18 by Kade Soprano

@inspectapedia.com.moderator,

No confusion. You have cleared it up.

On 2021-07-18 by inspectapedia.com.moderator - more than 3'8" variation in stair risers is unsafe

@Kade Soprano,

Right:

1. that is my grand daughter in the photo in question, though Quinn is much bigger now

2. those are not "my" steps in the photo in that I did not build them nor do I own them

3. those steps quite obviously vary in riser height by more than 3/8" and therefore are unsafe and would or should be considered a building code violation

Nothing in the > 3/8" rule puts a limit on "how much more than 3/8" - instead it says "more than 3'8" variation is unsafe"

4. I am the author of this document and editor/publisher of the website

We don't try to cite every possible violation or hazard in every photo, partly out of clutter and to avoid confusion, but I've added details to the photo and text above to try to avoid the confusion that your question has addressed.

Help me out: I remain confused by your questions.

The article states that steps with a riser variation of more than 3/8" are improper and unsafe.

Nothing in the article states that the steps in the photo are safe.

Whose granddaughter, whose steps, who built them, or who wrote the article ought make no difference in those points.

How has this page been confusing to you.

PS: you may need to clear your browser cache to see the updated images and text on pages where we've edited recently.

On 2021-07-18 by Kade Soprano

@danjoefriedman,

You see, I thought that was a photo of your steps since the caption read "...the author's granddaughter..." and I figured you were the author of the website text. But from the way you responded, apparently, you didn't mean "granddaughter of the author [of the website text]", so that is not your steps and they are not up to code.

I wasn't trying to be ugly. I apologize if it seemed that way in my previous comment.

On 2021-07-18 by Kade Soprano

@danjoefriedman,

I understand the code and the text just fine, so quoting it again doesn't answer my question. But I suppose your non-answer does answer my question, so thanks.

Have a good day.

On 2021-07-18 by danjoefriedman (mod)

@Kade Soprano,

"...this means that more than 3/8 of an inch in variation of the height of steps from one step to another is a tripping hazard."

On 2021-07-18 by Kade Soprano

@danjoefriedman, Yes, I know about the 3/8" variation, but in that photo, the rise from the ground to the first step has an obvious greater than 3/8" variation. It is much shorter than the other steps.

On 2021-07-18 by danjoefriedman (mod)

@Kade Soprano,

No, it is not okay to have a difference in Step Riser height it's a trip Hazard and I would expect your local building code inspector to object. The solution is to build a landing platform in order to get the rise correct.

I apologize if the photo was confusing and I'll review our text. It is the case that included not far below the photo is the following:

"Step riser height uniformity (<= 3/8" variation) - this means that more than 3/8 of an inch in variation of the height of steps from one step to another is a tripping hazard."

On 2021-07-18 by Kade Soprano

I noticed in the example photo of closed riser stairs (the one with the author's granddaughter) that the bottom step didn't have the same riser height as the other steps, as the height from the finished grade didn't allow.

I am currently building some steps and the finished height from the top of my porch to finished grade also does not allow a full riser height from bottom step to ground, unless I remove a step and extend the tread depth of the other steps by a significant amount, which is something I don't want to do. I would like to keep the tread depth at 12".

From the inclusion of your photo in your article and the absence of any negative comments about it, I assume this is okay to do?

On 2020-11-16 - by (mod) -

Ron

In most jurisdictions you need a handrail when there are 3 or more steps

and

if there is an open side to the steps you need a guard railing or stair guard along the steps too

Details are at HANDRAIL CODES & OSHA HAND RAIL SPECS

and at

HANDRAILS & HANDRAILINGS - home

When is it. Required to install a hand rail?

On 2020-09-02 - by (mod) -

Four risers or steps, Randy, and as we calculate the riser height as 29 / 4 we get each step rise height as 7 1/4" tall. That keeps us close to the ideal or desired step height.

On 2020-09-02 by Randy Anderson

How many steps would you have to have for a 29 inch high porch

On 2020-06-20 - by (mod) -

Sounds like a trip hazard, that's the first concern, and yes, quite possibly your local building code official will object

On 2020-06-20 by jtwatson932@gmail.com

Steps for built all risers and treads for the same height contractor came in and put blue stone in and now the bottom step is a lot smaller for the riser is that okay will it pass inspection?

On 2020-06-02 - by (mod) -

Im not a lawyer, but in my experience the building owner has responsibility for hazards at their own property

On 2020-06-01 by Kirk L

I’ve recently come across an issue where a concrete sidewalk was poured leading up to an exterior porch stair, and the height of the slab made the first step much lower than the rest (much like in your picture of Quinn above). In my understanding of the building code this is a trip hazard as it creates a very unequal riser and thus is not compliant.

My question is, who is responsible in terms of an accident or lawsuit. Obviously the original builder shouldn’t be, if they built a compliant stair, so I’m thinking the person who built the sidewalk should be responsible for fixing it (even if stairs are not their area of expertise) as they created the problem.

Or does the homeowner become responsible for allowing it to happen and paying the sidewalk builder prior to realising it wasn’t to code? If the sidewalk builder has a license can they be held accountable for their mistake?

On 2020-02-19 - by (mod) -

See your question you posted at

https://inspectapedia.com/Stairs/Stair_Tread_Dimensions.php

On 2020-02-19 by Lamont

What is the building code for building stairs from first floor to second floor in Maryland..

On 2019-11-29 - by (mod) -

Yes, steps may be under 7 " high.

7 is a recommended riser height, not the only one allowed. Eg. 6.75 or 7.2 are allowed

Risers should, however, be uniform

On 2019-11-28 by Doris

Is there a step riser height less than 7 inches

On 2019-04-30 - by (mod) -

Helena,

The article above you will see this standard

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.

the concern is that if you make the step rise less than 4 in you're more likely creating a tow catching trip hazard.

for seniors or anyone who has difficulty climbing stairs it's very important to attend all of the safety features such as lighting, handrails, and where appropriate color keys showing the edges of steps

See ELDERLY & VETERANS HOME SAFETY

See ADA STAIR & RAIL SPECIFICATIONS

On 2019-04-29 by Helena

What is minimum stair riser height for outside stairs ( such as for making it easier for elderly people to climb)?
To meet building codes requirements.

On 2018-08-01 - by (mod) -

That's an interesting question; you're basically extending the floor area by the width of a stair tread, right? Why would you do that? It pushes the whole stairway out by the depth of the stair tread in move that would be unnecessary - but then I can't see your situation, perhaps I'm missing something.

I don't think we'll find an explicit prohibition in the stair codes, since the code writers can't and don't try to anticipate every possible variation on what people may invent.

But a local building code inspector MIGHT interpret that top tread as a stair top platform.
If she does, then the stairs would be improper as the platform would be very much too short. A platform needs to run no less than 3 ft. in the direction of travel up and down the stairs, and yours would run what, maybe 11" - or whatever is your tread depth.

On 2018-08-01 by John R

Can the top tread of a stair stringer be the same elevation as the finish floor ?

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?

Reply:

Experts suggest that for more physically limited people the best way avoid falls is to seek living accommodations 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, handrail 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 of step design for people with physical limitations at STAIR DESIGN for SENIORS



...

Continue reading at STAIR TREAD DIMENSIONS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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

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


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