Stair tread dimensions, measaurements & step construction details & code specifications:

This document provides building code specifications for stair treads: sketches, photographs, and examples of defects used in inspecting the step design on indoor or outdoor stairs and their treads, including the requirements for a projecting stair tread nose and the tread nose shape and dimensions.

We discuss the use of color or other visual clues to reduce trip & fall hazards. We also include references to key documents on building codes and stair and railing safety.

Our photograph of badly worn stair treads (above) was provided courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Stair Tread Dimensions: Stair Tread Specifications & Safety Defects

This article discusses stair tread depth, stair tread nose profile & dimensions or projection, and stairway width.

Stair tread dimensions of width, depth, riser height and tread nosings as well as other tread and riser properties that reduce stair falls and that meet stair codes are detailed here.

Article Contents

• DEFINITION of STAIR TREAD DEPTH - distance from tread front nose to back riser, also called step run dimension. - typical minimum is 9", varies by jurisdiction; recommended: 11"
• DEFINITION of STAIR TREAD WIDTH - minimum stair tread widths (side to side distance) - typical minimum is 36" clear width but handrail can project 4 1/2" into that space
• STAIR TREAD DEPTH, SLOPE, UNIFORMITY - stair tread level requirements (or slope of walking surface) - typically no more than 1/4" per foot slope in any directfion
• STAIR STEP RISER HEIGHT - how tall can a step be? - typical maximum is 7 3/4" or 8" in sopme jurisdictions, with variation of no more than 3/8" between successive steps
• STAIR TREAD NOSE REQUIREMENTS - how should the leading edge of a step be treated? - Projects 3/4" to 1.5", curve radius <= 9/16"
• STAIR TREAD THICKNESS CODE - minimum tread thickness - 1" thick if supported by front riser, 1 1/2" thick if no riser; too thin may break.
• STAIR TREAD WOOD CHOICE vs FALL RISKS - walking surface slipperiness varies
• STAIR TREAD COLOR CUES REDUCE FALLS - color differences between steps and risers or landings
• Also see RECOMMENDED ARTICLES for details of stair risers, landings, etc.
• Also see INDEX to RELATED ARTICLES for the full index for our complete list of stair, ramp, handrail and guardrail articles.

Definition of stair tread (tread depth)

Define stair tread: The stair tread is the horizontal walking surface of an individual step.

The stair tread surface is the space beneath the right foot of the person about to slip and fall down these irregular stone steps at la Canada de la Virgin in Guanajuato. These stairs were built by the Otomi in the valley of what is today San Miguel de Allende around 530 AD - a bit before modern building codes.

In our photo you may notice signs of modern cement that has been used to stabilize, repair and improve th walking surfaces, but the stones and dimensions of these ancient steps are about 1,500 years old.

We've marked my photo using colored arrows to illustrate the meaning of common stair dimensions.

Define tread depth:

the stair tread depth (red arrow) 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.

Stair tread depth is also called step run - the distance in the direction of movement of the user.

Stair tread depths shall be 11 inches (279 mm) minimum. (Recommended) The International Residential Code (IRC) specifies a minimum of 10".

*Smaller depth or run is permitted in some jurisdictions but steps with a depth or run of less than 8 or 8 1/2" are difficult to use and are a fall hazard.

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.

Define stair tread width:

the stair tread width (blue arrow in my photo of stone steps) is the total available walking surface across the stairway opening.

Define stair riser:

A stair rise or riser height (green arrow) is the vertical distancebetween the walking surface of two stair treads is the stair riser or riser height.

On the stone steps shown above, the step risers are the vertical faces of stones used to build each step. Open riser stairs have no enclosure.

Closed riser stairs include a vertical riser board that adds support below the stair tread. Stair risers are detailed at STAIR RISER SPECIFICATIONS.

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.

See STAIR HEADROOM for details.

Stair tread nose

(yellow arrow in the photo of stone steps above) is the projection of the stair tread out over the stair riser.

The tread nose defines the outer edge of each tread walking surface. The stone steps up the pyramid shown above don't have a tread nose, and worse, the stones are irregular and worn, making falls more-likely.

The edge of the stone step below the stasir user's feet is worn and sloped. She's taking care to avoid a fall.

Definition of Stairway Width or Stair Width - don't confuse stair width with stair depth

Define Total Stairway width,

(blue arrow in this photo of a wooden staircase) is the total width of the stairway opening: the horizontal space between stairway walls if there are walls on either side of a stair, or the space between the inner-most surface of the stair guards if there are guards along a stairway instead of closed-in walls.

For stairs enclosed by a wall on both sides, usually the total stairway width is the distance between those walls.

Define Usable Stairway Width:

(green arrow in the photo) is the un-obstructed horizontal distance or space through which the stair user's body can pass when climbing or descending the stairs.

The usable walking surface along the width of stair treads will normally be less than the total stairway width, and less than the stair tread width.

That's because the total stairway width is further reduced by

• Wood trim along the sides of a stair built between walls in the photo, because the wood trim along the sides of the stairway intrudes into the space between the stairway walls, the stair trad width is made less than the stairway width by the thickness of the trim boards.
• Handrailings along one or both sides of some stairways intrude a few inches into the walking space.

Our photo of a wooden stairway illustrates three different stair width measurements

1. Stair tread width (green arrow) (smaller than stairway width due to side trim boards)
2. Stairway width (blue arrow) over most of this stairway (nominally 36")
3. Further-reduced stairway width near stair top (pink arrow) due to a wall projection (nominally 35")

Watch out:  it's confusing but many people refer to stair tread depth as stair step or tread width, including our Canadian stair dimension illustration just below.

If you stick to using the word stair tread depth you can avoid this confusion. Oops, that is, unless you start confusing tread depth with stair tread riser height.

You might want to double-check the definitions of stair tread depth, tread width, and riser height given above on this page.

Stair Tread Depth (Width) Requirements Vary by Open or Closed Stairway Risers

Closed stair treads using a solid riser are shown at the left of the sketch and open stair treads are shown at the right sketch.

Notice that the minimum stair tread thickness is increased when the stair tread is not supported by a solid riser.

Note that some of these dimensions pertain to Canadian building codes. U.S. stair codes and OSHA stair specifications may vary. The illustration shows a step rise of 8 to 8 1/4" but in the U.S. the recommended rise is 7 - 7 1/2"

See details on tread specs also found

at STAIRS, RAILINGS, LANDINGS, RAMPS

Sketch above was provided and used with permission courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Stair Step Tread Depth, Uniformity & Slope Specifications

• Step tread depth (=> 10") (measured 12" from smaller side of irregular stair shapes such as triangular treads on curves or spirals)
• 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) -- Source: IRC
  
  This means that the walking surface of a stair tread must slope no more than 1/4 inch per foot in any direction.
  
  (We may deliberately slope exterior stairs about 1/8" per foot to improve stair walking surface drainage.)

The stair treads shown in our photo are very dangerous not only because they are pitched and loose, but because there is danger of stairway collapse.

The tread slope and collapse risk are visually obvious.

The stair inspector should be asking:

"What caused this weird movement and who made these goofy repairs?"

and

"What other work did that person perform on this building?"

 

Stair Stair Tread Depth & Step Riser Height Dimension Requirements

The photo above shows a stair tread that lacks enough depth - this stair tread was only about 7 inches. My foot illustrates that this is an un-safe and hard-to-use stair tread: my the boot toe is against the stair riser and my heel extends well past the stair tread nose.

Exactly Where & How to Measure Stair Tread Depth

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.

Where stair tread depth is very small, such as the stone pyramid steps shown below, smart users will step sideways to ascend or descend the stairs.

In the stone steps shown above (one of the Becan pyramids in Campeche, Yucatan, Mexico), I'm forced to step with my foot sideways and still it just fits on the tread surface.

Exactly where & how to Measure Stair Riser Height

Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. - Example from BOCA Code 2001

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

Above and below: the very tall step riser heights at a Becan pyramid are, nonetheless, easier to climb up than down, as illustrated by my friend, New York film maker Ralph Arlyck.

Also see

STAIR RISER SPECIFICATIONS

STAIR DIMENSIONS, WIDTH, HEIGHT

Why Build Steps with Tall Risers & Narrow Treads?

Like the wooden steps shown above, ascending to the attic in the Justin Morril Smith historic home built between 1848 and 1851, carpenters build narrow-riser tall tread stairs in places where there is not sufficient horizontal run to fit an easier-to-climb stairway that would ascend more gradually.

More about the Gothic Revival style [photo] Justin Morrill Smith home including links to articles about what we found in the attic reached by these stairs can be seen

at ROOF ARCHITECTURAL STYLES.

High-rise, narrow-tread steps have been de-rigeur for thousands of years, including those shown at the Becan pyramids in the Yucatan.

Had modern tourists had instead been among been the Mayan people having to carry and place the stones to build th huge pyramid (shown below) in 550 BCE, we might have understood the appeal of making steps narrow, and tall, so as to ascend to the required height with fewer trips to the quarry.

Above: Steep stone steps rise to the top of Estructura IX, Becan, Campeche, Yucatan. This is the tallest building in Becan, rising 32m above the plaza.

Stair Step Tread Nose Projection Requirements & Stair Code Citations

Definition of stair tread or landing nose or nosing

The leading edge of treads of stairs and of landings at the top of stairway flights. - IBC 1002 [14a]

Details about the proper design of stair tread nosings in shape & dimensions as well as history, research & stair tread nose hazard discussion are

at STAIR TREAD NOSE SPECIFICATIONS

Excerpts are below:

While a tread nose is not required on stairs with open risers, closed riser stairs like these should have a tread nose projection that (for jurisdictions that require stair tread or step noses) are typically as specified below:

• Tread nose projection past vertical riser below (3/4" to 1 1/2") required on stairs with solid risers (exceptions are below)
• Tread nose projection uniformity (<= 3/8" variation)
• Tread nose curve radius (=< 9/16")
• Tread Nose not required if tread depth is => 11"
• Tread Nose not required on open stair treads (open riser)

Watch out: some jurisdictions may have other stair tread nose design requirements and some may prohibit stair tread nose projections entirely.

See details at STAIR TREAD NOSE SPECIFICATIONS

Stair Tread Thickness Requirements

The thick "timber" wood open riser stairs shown here were photographed in Oxaca. [Click to enlarge any image]

There is no single minimum nor maximum stair tread thickness specified by stair building codes for all possible stair tread materials.

That's because a variety of materials might be used, ranging from thin steel to strong oak to soft pine.

However, at STAIR TREAD NOSE SPECIFICATIONS as well as above in more-succinct form, you'll see that for closed-riser stairs a tread nose is required, that must project out sufficiently and must have a radius no less than 9/16" - that would determine a minimum tread thickness for wooden treads; for steel stairs there would be a bend to provide the nose.

For wooden stair treads the tread thickness must be

1. Tread Strength: thick enough to be adequately strong as not to split or break under use - that varies by wood species
2. Tread w/ Front riser-support: no less than 1" thick if the tread is supported by risers under its front edge,
3. Tread w/ Open Risers: otherwise no less than 1 1/2' thick.

Note that there is no maximum stair tread thickness, Nevertheless, very thick stair treads, say using "timbers" greater than 1 1/2" thick (typical 2x lumber thickness) might be hazardous:

Watch out: in my OPINION a tread that is too thick might also have a tread nose that is too thick and might be a trip hazard to people ascending the stair.

Effects of Stair Tread Lumber Type on Risk of Damage & Stair Falls

Opinion: Daniel Friedman.

Any broken away or uneven tread nose is a trip and fall hazard. A question sometimes arises about the role of choice of materials in the chances of a stair fall due to tread or tread nose breakage. Does the lumber type of species make much difference in this risk?

Possibly so insofar as treated wood Southern Yellow Pine lumber may present a greater chance of having a breakaway around knots than other choices such as cedar or even plastic wood deck & tread lumber materials.

Nevertheless, the decision to use treated lumber itself should have little useful bearing on a stair fall case as it's both common practice and in some regards is a safer choice to use treated lumber over non-treated pine or SPF since preservative treatments, by reducing the risk of structural rot, should make a wood stairway more durable and safer than more rot-prone choices. .

Most treated wood used in North America is Southern Yellow Pine (SYP) impregnated with preservative salts.

The wood is often quite wet with preservative when purchased, it will even squirt when nailed.

But since cessation of the use of more toxic wood preservatives (such as CCA), treated wood is not more inherently hazardous when you remove a piece of the tread nose than any other wood, with a small, weak, technical exception.

SYP is generally a more knotty wood than some alternatives such as cedar decking.

A property of SYP is its inherent knottiness and tendency to warp.

So depending on what alternative and more costly wood that might be use for decking, say cedar, there is a non-quantifiable greater chance that a knot appears at5 or close to the edge of a board and thus could end up on a stair tread nose.

The presence of a knot at the edge of wood used to build a stair tread produces a form of weakness of the wood in that area in that the weight of someone stepping on the edge of the tread nose might break the nosing away on either side of the knot.

Openings around knots can also hold water and in a freezing climate an thus contribute to ice or frost cracking and damage to the wood in that area.

Breakaway on either side of a knot in the wood near the edge of the walking surface is what we observe in your video of the area of damaged tread nosing in your video.

We haven't established if the break occurred at the time of the fall or prior to it, but I consider it most likely that at least part of the tread nose was broken away before the fall because I observe breakaway of several inches on both sides, left and right, of the knot - not something that would be likely to occur by a single event of a single foot pressure over that area.

Watch out: Builders constructing wooden stair treads using dimensional lumber or 5/4 lumber (deck boards) should take care that the nose of stair treads does not include knots or other damage that increase the risk of a future stair tread breakaway.

What about slipperiness of treated wood decks or stairs when wet? Is treated lumber more slippery than other decking?

More slippery than what?

The hardness of lumber species varies as does surface texture; cedar (used on more expensive decks, steps, rails) for example has a somewhat more grainy surface and may be less slippery than treated wood when dry.

But I doubt that a coefficient of friction of wet vs dry woods by species has much useful bearing on a stair fall case as it is absolutely standard common practice to use treated lumber on outdoor decks, balconies, stairs, and even railings and balusters.

The really horrible stairs in our photo above are installed at a Poughkeepsie NY home surrounded by shade trees.

The 2x6 treads (actually 5 1/2" in depth) are exactly 1/2 of the recommended tread depth and are covered with algae that will be hysterically slippery when wet.

And the faux hand railing made of pipe extends just about 20 inches above the stair treads, lacking stair guards (a child hazard), not at a usable rail height, with flimsy attachments to the structure.

These stairs at the previous home of our friends Steve and Judith G. are treacherous.

But we find algal growth can occur on all species of wood used for exterior stairs as well as on some other surfaces, even concrete.

Watch out: the green deposits shown on these woodne steps tells us that there is algae growth on the walking surfaces.

Algae on stairs, steps, decks, or wooden ramps, particularly when the surface is wet, forms one of the slipperiest surfaces known - it is extremely dangerous, risking a stair fall.

Details about algae, ice, snow, water and other slippery stair and walking surfaces are found

at SLIPPERY STAIRS, WALKS, ROOFS.

Impact of Post-construction Wood Treatments & Preservatives on Exterior Deck or Stairway Slip Hazards

There are other treatments that can be applied to outdoor wood decks, balconies, rails, such as preservative stains (recommended by manufacturers but not required by codes). Such preservatives or stains are used on both treated wood and also on cedar decking, and some paints are also used on synthetic decking.

For wood surfaces these add-on products extend the life of the structure, improve its appearance, and many provide some water repellence to the surface - factors that further reduce the chances of formation of slippery algae on the walking surface.

These are the most common causes of slippery stair treads, steps, or other outdoor walking surfaces

1. Snow or ice in areas of freezing climates
2. Algal growth or on occasion fungal growth on the wood surface, largely affected by the presence or absence of sun exposure
3. Water improperly directed on the deck or stair surface due to mis-routing of roof drainage systems

See ALGAE, ICE, FUNGUS, WET Surfaces & Other Stair Slip, Trip & Fall Hazards for details.

Also see EXTERIOR STAIR FALLS for a catalog of causes of falls on stairs that includes surface conditions and other defects.

Use of Color or Lighting to Indicate Stair & Step Changes Can Reduce Trip & Fall Injuries

Here we illustrate cases of the presence or absence of visual cues that can inform a walker that she is approaching a step. The use of color to provide a noticeable contrast between the walking surface of a passageway or floor and its steps or stairs can reduce trips and falls for walkers in either direction.

Our photo above illustrates a handrail that is indeed "graspable" - a concern in any location, but particularly here at the Metropolitan Opera at an upper balcony where of necessity stairs are angled and steep.

You'll notice that the Met also gives visual clues (a light colored carpet strip) to help walkers discern the location of the stair tread edges.

Below: where the walking surface and stair tread surfaces are the same color and appearance, falls are more likely.

The stairs above, observed in San Miguel de Allende, do a good job of providing color cues for both ascending and descending the stairway.

Below: where both the upper walking surface and the stairs are of the same material - brick, wood, or carpet - such that there are not obvious visual clues to indicate where the steps are, low light or for people with reduced vision, such stairs are dangerous.

Using a non-slip, glow-in-the-dark tape to mark the edge of the stair treads reduces that risk.

More photos of the non-slip stair tread edge marking tape under various lighting conditions are given

at SLIPPERY STAIRS, WALKS, ROOFS

Lighting Cues Help locate Edges of Steps & Reduce Falls

At Lincoln Center in New York City, these exterior stairs make good use of lighting to reduce the chances of stair trips and falls.

Also see LIGHTING OVER STAIRS & AT EXITS.

Lack of Color, Lighting or Other Visual Clues Increases the Risk of a Stair Fall - Examples

The slippery tile walking surfaces shown above and the very short step up - less than 3cm - is a near guarantee of stubbed toes.

A step like this also invites a trip and fall - in this case head-long into the toilet in the bathroom. This floor height difference was observed in a New Zealand hotel.

The tile floor shown here includes a 4-inch step up into a bathroom. Because the same color tiles were used on the floors at both levels as well as on the step riser, it is very difficult to see that there is a step, especially in low light.

In fact the author (DF) tripped on this very step, located in a hotel in Tapalpa, Mexico. We placed a water bottle on the floor to provide a visual clue of the presence of the step riser for our photograph.

Stairs and steps  can use a color change or a tile layout change to indicate a change.

In our photo at above left, taken in a restaurant in Rhinebeck, New York, it is still not clear from the upper walking surface whether or not we are approaching a step.

How to Fall Down the Stairs - Guaranteed: Place Throw Rug as Visual Cue of a Step

Watch out: A throw rug or carpet at the top of a stairway is asking for a serious stair fall even if it does provide a color change. This is not a safe way to give a visual clue about the presence of a step.

Do not place slippery items such as a my folded saddle blanket (shown above) or any other rug or towel on a smooth floor at the top of steps or stairways such as the steps shown in our photo above.

See details at SLIP TRIP & FALL HAZARD LIST, STAIRS, FLOORS, WALKS

Supporting Research on Stair Tread Dimension Safety

• Foster, Richard J., John Hotchkiss, John G. Buckley, and David B. Elliott. SAFETY ON STAIRS: INFLUENCE OF A TREAD EDGE HIGHLIGHTER AND ITS POSITION [PDF] Experimental gerontology 55 (2014): 152-158.
  
  Highlights
  
  We studied if fall risk during stair descent was reduced by using step edge highlighters.
  
  A highlighter placed flush with step/tread edge improved foot clearance precision.
  
  Foot clearance precision was reduced when the highlighter was set back by 30 mm.
  
  Benefits of the highlighter were greater in those with simulated visual impairment.
  
  Fall risk may be reduced by using a highlighter positioned flush with the tread edge.
  
  
• Foster, Richard J., David Whitaker, Andrew J. Scally, John G. Buckley, and David B. Elliott. "What You See Is What You Step: The Horizontal–Vertical Illusion Increases Toe Clearance in Older Adults During Stair Ascent." Investigative ophthalmology & visual science 56, no. 5 (2015): 2950-2957.
  
• Kunzler, Marcos R., Emmanuel S. da Rocha, Christielen S. Dos Santos, Fernando G. Ceccon, Liver A. Priario, and Felipe P. Carpes. "Should we consider steps with variable height for a safer stair negotiation in older adults?." Work 59, no. 1 (2018): 15-21.
  
  Abstract:
  
  BACKGROUND: Effects of exercise on foot clearances are important. In older adults variations in foot clearances during walking may lead to a fall, but there is a lack of information concerning stair negotiation in older adults. Whether a condition of post exercise changes foot clearances between steps of a staircase in older adults still unknown.
  
  OBJECTIVE: To determine differences in clearances when older adults negotiate different steps of a staircase before and after a session of aerobic exercise.
  
  METHODS: Kinematics data from 30 older adults were acquired and the toe and heel clearances were determined for each step. Clearances were compared between the steps.
  
  RESULTS: Smaller clearances were found at the highest step during ascending and descending, which was not changed by exercise. Smaller clearances suggest higher risk of tripping at the top of the staircase, regardless of exercise.
  
  CONCLUSION: A smaller step at the top of a short flight of stairs could reduce chances of tripping in older adults.
  
  It suggests that steps with variable height could make stair negotiation safer in older adults. This hypothesis should be tested in further studies.
  
• Startzell, Jill K., D. Alfred Owens, Lorraine M. Mulfinger, and Peter R. Cavanagh. "Stair negotiation in older people: a review." Journal of the American Geriatrics Society 48, no. 5 (2000): 567-580.
  Abstract:
  
  Locomotion on stairs is among the most challenging and hazardous activities of daily living for older individuals. This is evidenced by the reports that stair falls account for more than 10% of fatal fall accidents.
  
  The demands that stairs place on the musculoskeletal and cardiovascular systems are compounded by the need for input from the somatosensory, visual, and vestibular systems at various stages in the task.
  
  Many of these collaborating systems deteriorate with aging, thus increasing the difficulty and risk of failure in a task that inherently involves exposure to significant danger.
  
  The task itself varies in its degree of challenge depending on many structural and environmental factors that are outside the control of the stair user.
  
  This review explores existing literature in the area of stair negotiation by older persons in an effort to define the key factors associated with difficulty and safety on stairs and to interpret these findings in the light of possible interventions that could increase stair safety.
  
  Further research is needed to ensure that current recommendations for stair design are suitable for older stair users. A Glossary of Terms is also provided. J Am Geriatr Soc 48: 567–580, 2000.
  
• Novak, Alison C., Vicki Komisar, Brian E. Maki, and Geoff R. Fernie. "Age-related differences in dynamic balance control during stair descent and effect of varying step geometry." Applied ergonomics 52 (2016): 275-284.
  Abstract
  
  The incidence of stairway falls and related injuries remains persistently high; however, the risk of stair injuries could be reduced through improved stairway design. The current study investigated dynamic balance control during stair descent and the effects of varying the step geometry.
  
  Data were collected from 20 healthy young and 20 older adults as they descended three staircases (riser heights of 7, 7.5 and 8 inches (178, 190 and 203 mm, respectively)).
  
  At each riser height, the tread run length was varied between 8 and 14 inches (203 mm and 356 mm) in one-inch (25 mm) increments.
  
  Kinematic data provided measures of segmental and whole-body dynamic control. Results demonstrated that older adults had greater lateral tilt of the upper body than young adults, but actually had larger margins of stability than the young in the antero-posterior direction as a result of their slower cadence.
  
  Nonetheless, for both age groups, the longer run lengths were found to provide the largest margins of stability.
  
  In addition, increase in run length and decrease in riser height tended to reduce forward upper body tilt. These results help to explain the underlying biomechanical factors associated with increased risk of falls and the relationship with step geometry.
  
  Considering the importance of stair ambulation in maintaining independence and activity in the community, this study highlights the definite need for safer stair design standards to minimize the risk of falls and increase stair safety across the lifespan.
• Reeves, Neil D., Marcel Spanjaard, Amir A. Mohagheghi, Vasilios Baltzopoulos, and Constantinos N. Maganaris. "The demands of stair descent relative to maximum capacities in elderly and young adults." Journal of Electromyography and Kinesiology 18, no. 2 (2008): 218-227.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

What is the best stair tread height for seniors & handicapped people?

How far apart should the height be in inches for senior citizens in the handicapped be? - On 2020-05-15 by Dkprince52 @gmail.com -

Reply by (mod) - special stair tread dimensions for disabled or elderly?

DK

thanks for an interesting question. Because we don't assume that you should build different stair treads suited just to the elderly or disabled I re-phrase it as

Should stair tread height be different for the elderly or disabled?

That's a tricky opinion to voice, because optimizing the stair tread for any one physical ability risks making it into a fall hazard for other stair users. There's a lot of research on this, some of which I'll cite below.

In my OPINION, while a shorter rise such as a 5-inch step rise may be easier for some people to climb, the most-important stair features to reduce falls or fall injuries are those I list below.

It's interesting, too that some key research on the effect of stair step riser height on falls among the elderly studied higher rises such as comparing 7-inch, 7.5 inch and 8 inch riser heights - rather than lower or "shorter" riser heights.

- stairway lighting - dim, poorly lit or lack of color or visual contrast makes for stair falls

- stair tread noses that are visually obvious - using tapes, bright colors, helps people see the tread edge

- stair tread depth (the "width" onto which a person can step.

- properly located, designed graspable and strong handrailings that help people balance and also help arrest or reduce the severity of a fall

See RESEARCH on STAIR SAFETY in this article

9 inch treads are hard to use: how much can I increase tread depth for these stairs & what wood should I use?

I have an attic apartment with outdoor stairs that have a greater degree of incline. The thread depth is 9inches and it is difficult to walk up and

I have an attic apartment with stairs that have a greater degree of incline. The stair tread depth is only 9 inch and it is more difficult to move up and down.

What is the most I can increase the depth.

Also, what wood do you recommend and how wood I finish them. They are a natural weathered looking wood now. Not finish protected at all. - On 2020-05-07 by Hank Maida -

Reply - by (mod) -

Hank,

It does sound as if the stairs have small, difficult treads, but unfortunately one cannot simply install deeper treads. The stair would have to be replaced.

Draw it out and you'll see that deeper treads would hang out over successive steps and trip stair users

What is the code for stairs from 1st floor 2nd floor inside row house in Maryland?

What is the code for stairs from 1st floor 2nd floor inside rowhouse - On 2020-02-19 by Lamont -

Reply - by (mod) -

Maryland's law related to building codes is called the Maryland Building Performance Standards (MBPS). It requires each jurisdiction in Maryland to use the same edition of the same building codes that are the International Building Code (IBC), the International Residential Code (IRC), and the International Energy Conservation Code (IECC). The State has modified the IBC and the IRC to coincide with other Maryland laws.

The International Building Code (IBC), the International Residential Code (IRC), and the International Energy Conservation Code (IECC), with modifications by the State, constitute the Maryland Building Performance Standards (MBPS).

Each local jurisdiction in Maryland may modify these codes to suit local conditions with exception to the 2015 International Energy Conservation Code (IECC - The Energy Code) and Maryland Accessibility Code (MAC - The Accessibility Code). The Energy Code and the Accessibility Code can be made more stringent but not less by the local jurisdictions. - Source: www.dllr.state.md.us/labor/build/buildcodes.shtml

So you can start with a look at the model codes at

STAIR CODES - free PDF downloads,

Therein you'll see stairs and stair dimensions discussed in several sections such as

SECTION R311 MEANS OF EGRESS

Are intermediate handrails required in New York City?

Are intermediate handrails required at exterior stairs in NYC - On 2018-11-01 by Roger -

Reply by (mod) - intermediate handrails

If by intermediate handrails you are referring to a railing at half height such as might be convenient a long-assed are used by children, no I have not seen that requirement in any building code. However it makes perfect sense and certain environments.

What is the minimum allowed thickness of timber treads on stairs?

What is the minimum allowed thickness of timber treads on stairs? - On 2018-08-21 by Marie -

Reply by (mod) - Codes & Rules on Stair Tread Thickness

Marie

Codes & Rules on Stair Tread Thickness

There is no single tread thickness specified by stair building codes. That's because a variety of materials might be used, ranging from thin steel to strong oak to soft pine.

However, in the article above, take a look at

Stair Step Tread Nose Projection Requirements & Stair Code Citations

You'll see that for closed-riser stairs a tread nose is required, that must project out sufficiently and must have a radius no less than 9/16" - that would determine a minimum tread thickness for wooden treads; for steel stairs there would be a bend to provide the nose.

For wooden stair treads the tread thickness must be

1. thick enough to be adequately strong as not to split or break under use - that varies by wood species

2. no less than 1" thick if the tread is supported by risers under its front edge,

3. otherwise no less than 1 1/2' thick.

Note that there is no maximum stair tread thickness, Nevertheless, very thick stair treads, say using "timbers" greater than 1 1/2" thick (typical 2x lumber thickness) might be hazardous:

Watch out: in my OPINION a tread that is too thick might also have a tread nose that is too thick and might be a trip hazard to people ascending the stair.

2008 NYS Stair Code: R311.5.3.1 - Stair Riser height Requirements.

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.) (Courtesy Arlene Puentes).

Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads.

I think 10 inch stair treads are the minimum allowed depth

Incorrect info in article...Near top, under "Definition of stair tread (tread depth)"
You write "

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

Fact: minimum stair tread depth is 10 inches minimum - On 2016-12-30 by Andy M. -

On 2016-12-31 by (mod) -

Andy,

Thank you for your comment. One needs to look with care and Stair Codes, since the specifications vary depending on the model code that your state,peovince, or local authorities have adopted. In the articles in this series and in the references section of each article we cite model codes and specific ones too.

A citation for your 10 inch depth will be welcomed.

Stairs have to have 11 inch tread and 7 inch rise (says Tom)

Your stair Diagram is wrong. Stair tread is 11 and riser is 7 unless your stair meets exceptions
and nosings are 1" - On 2016-04-25 by Tom Taylor -

On 2016-07-01 by (mod) -

Tom, thanks for your comment. But the dimensions you give, 11" tread depth and 7" riser height are not the only allowable stair measurements.

 

Question: building code on stair tread relining

I have to skin some new construction stairs, i am going to go over the stairs with a hickory [tread] and was wondering is there a code on tread skins? - Mike

Reply: minimum vs maximum stair tread thickness: needs clarification

Mike,

Re-covering worn stair treads by installing new treads atop the original ones is a common renovation procedure.

I haven't been able to find a code citation on your question but am still looking and will report here. 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. [2]. The ADA provides a comparison of stair standards among ADA and other requirements, also with no mention of tread thickness.

Watch out that your new stair skin doesn't create uneven step rise heights at the top or bottom of the stairs, nor a trip hazard at the top landing platform.

Also, let me know what you mean by "construction stairs" as OSHA has some different requirements for stairs depending on their intended use.

Question: 4/14/2014 Bernadette said: If my deck height is 5'6", how many steps would I need?

If my deck height is 5'6", how many steps would I need?

Reply: how to calculate the number of steps and the step riser height - and adding a trick or two

Bernadette, in our article on Stair Risers found at STAIR RISER SPECIFICATIONS we note that 7" is a reasonable step height. When calculating the exact riser height from stair tread surface to stair tread surface we divide the total rise height (you say 5'6") in inches (yours would be 66") by a good riser height (say 7") to get the number of steps we need, and then decide how to spread the fraction uniformly over all of the steps. This isn't the only approach but it works.

66" (total rise) / 7" (ideal step rise) = 9.42 steps. Since we can't build a fractional step, we round up (which gives a lower rise) or down (which gives a greater rise or step height).

Let's try just 9 steps.

66" / 9 steps = 7.3" per step rise - so we can if we want, build 9 steps of uniform rise of 7.3" each.

Or we can play tricks to make the job easier by constructing a landing at the first step that brings us up off the ground height by an amount to make all of the steps some other height that we want by changing the effective total rise. For example,

Assuming that we don't want our first step to end up in a hole to create a greater total rise, we can figure instead how high a landing platform would be above grade before the bottom-most step by building a regular stair with a nice step height that ends close to but less than our 66" total rise, then add a bottom level stair platform to bring the landing height up to the necessary level.

Here's an example, sticking with 9 risers but adding a landing platform:

9 risers x 7" rise per riser = 63" total rise

66" (required total rise) - (63" rise from our 9 risers) = 3" to make up by the landing platform.

So if we want we can make a large 3" tall platform at the stair bottom to serve as a final landing - which may be a good idea anyhow if the landing ground is not level. The platform must be at least 36" long in the direction of travel and at least as wide as the stairway.

So the total rise of 66" will be made up of the 3" platform plus 9 steps each of whose rise is 7".

9 (risers) x 7" (riser height) = 63" of riser height gain + 3" of platform height over bottom grade = 66" = 5'6" height that you cited.

Watch out: when measuring the total height gain needed to your deck. If the ground is not level you need to project a horizontal line out from the deck surface for the distance of the stairway run (horizontal distance of travel) and measure height or total height gain needed at that point. Else your stairs won't fit.

Question: what's the maximum step tread riser height that is safe?

(July 8, 2014) Yvonne Haynes said:
Our Church has just lowered the porch floor which means the stone step down into the Church has increased in height. We have had a few stumbles and one fall. Is there a maximum depth that a step should have to be deemed safe? Thank you.

Reply:

Yvonne,

Yes please see inspectapedia.com/Stairs/Stair_Dimension_Specifications.php

If the riser height is more than about 7" or 7.5" it's too high for normal traffic.

Question: Do we have to rise the marble a bit from front edge in marble stairs to avoid falling?

(Sept 24, 2014) Mir Mohsin said:

Do we have to rise the marble a bit from front edge in marble stairs to avoid falling?
How should we make the nosing of the tread? Should it be rising a bit more

Reply:

Stair treads should not be deliberately made to slope or "not level" and doing so, especially on marble stair surfaces that can be slippery when wet, you would be increasing the trip hazard.

You may need to install anti-slip tapes or strips on the treads.

Question: are stair treads without nosing legal?

(Oct 7, 2014) Rody said:
New exterior concrete stairs were built around the City Hall of Los Angeles without nosing. Is that legal now?

Reply:

Rody:

"Legal" in *any* building code jurisdictions is a final determination in the hands of the building code compliance inspector - for whom codes are guidelines.

Stair noses are indeed an interesting question since in some countries and jurisdictions experts do not agree that a stair nose reduces trips and falls.

Certainly I've seen alternative stair designs including a stairway whose risers sloped outwards from the riser bottom towards the top of the tread above.

...

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

Or see these

Recommended Articles

• RAILING CODES & STANDARDS
• SLIP TRIP & FALL HAZARD LIST, STAIRS, FLOORS, WALKS
• STAIR CODES & STANDARDS - free downloadable PDF files of building codes & standards
• STAIR RISE & RUN GEOMETRY & CALCULATIONS
• STAIR DIMENSIONS, WIDTH, HEIGHT
  • STAIR ANGLE & SLOPE
  • STAIR DESIGN for SENIORS
  • STAIR DESIGNS for UNEVEN / SLOPED SURFACES
  • STAIR CONSTRUCTION IDEAL DIMENSIONS
  • STAIR CONSTRUCTION, LOW ANGLE SLOPE
  • STAIR CONSTRUCTION, SPECIFIC ANGLE or SLOPE
  • STAIR CONSTRUCTION, SPECIFIC TOTAL RISE & RUN
  • STAIR HEADROOM
  • STAIR PLATFORMS & LANDINGS
  • STAIR RISE & RUN CALCULATIONS
  • STAIR RISER SPECIFICATIONS
  • STAIR STRINGER SPECIFICATIONS
  • STAIR STRINGER DEFECTS
  • STAIR TREAD DIMENSIONS
  • STAIR TREAD - HALTING WALK STUTTER STEP
  • STAIR TREAD NOSE SPECIFICATIONS
  • STAIR USER FOOT & HAND PLACEMENT

Suggested citation for this web page

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

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to STAIRS RAILINGS LANDINGS RAMPS

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