Photograph of a stair that is a real trip hazard. Design & Build Specifications for Stairs Railings Landings
Stair construction or Inspection codes, design specifications, measurements, clearances, angles for stairs & railings

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Stair, railing, guardrail, handrail, landing & platform building design & build specifications: summaries of stair and railing code & design specifications quoted from model building codes.

For each stair specification & code citation we include links to in-depth articles providing more details.

This article series lists all major building code specifications for stairs, railings, landings, and guardrails - information useful for constructing or inspecting indoor or outdoor stairs, railings, landings, & treads, and for evaluating stairways and railings for safety and proper construction.

We compare stair and railing code requirements for various model, national, state and local building codes and we include explicit text & specifications from those building codes.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Guide to Building Codes for Stairs & Railings, Stair Landings & Guardrails

Stair dimensions (C) Carson Dunlop AssociatesHere we illustrate and summarize typical building code requirements for stairs, railings, landings, and guardrails. We also include references to key building codes that provide more detailed specifications for stair, landing, and railing safety.

[Click to enlarge any image]

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 article has been adapted from specific stair and railing specifications that are similar among codes and countries (but not identical). -- IBC, IRC, BOCA, Kingston NY Stair Code, New York State Residential Building Code for Stairs (included here), Florida, Pennsylvania, New Jersey, & other sources.

In-depth stair design articles listed at the ARTICLE INDEX the bottom of this article provide detailed descriptions of each stair feature, building codes, photographs and sketches of defects and requirements. Text comparing key provisions of several building code sections on stairs and rails is given at the end of this document.

We provide sketches and photographs of stair, railing, landing, and construction details and hazards

Sketch courtesy Carson Dunlop Associates.

Article Contents:

Stair component & topic summary specifications & codes are given in this article.

At More Reading we give a complete list of in-depth individual articles about each stair component, code, & design point.

Balusters for Guards & Railings

Stairway Lighting requirements (C) Carson Dunlop AssociatesStairway handrail & stair balusters & guard details are in this sketch.

See GUARDRAILS on BALCONIES & LANDINGSfor details. A summary is below.

Balusters (vertical posts comprising the barrier in guards and railings)

Hand-railing heights are given:

Sketch courtesy Carson Dunlop Associates.

Details about guardrail or railing balusters are at

Building Egress: EXIT Stairs & Exits

Unsafe exit stairs (C) Daniel Friedman at Real de CatorceBuilding exits, particularly in an emergency, are likely to be a source of additional injuries or worse if they are not properly constructed.

Where a stairway is generally not used and falls into abandonment, such as a "second means of egress" that is not normally accessed, serious trip hazards often develop.

The exit stair shown here, from Real de Catorce, would be a disasater in an emergency.


1007.1 Accessible means of egress required.

Accessible means of egress shall comply with this section. Accessible spaces shall be provided with not less than one accessible means of egress.

Where more than one means of egress is required by Section 1014.1 or 1018.1 from any accessible space, each accessible portion of the space shall be served by not less than two accessible means of egress.


1. Accessible means of egress are not required in alterations to existing buildings.

2. One accessible means of egress is required from an accessible mezzanine level in accordance with Section 1007.3 or 1007.4.

3. In assembly spaces with sloped floors, one accessible means of egress is required from a space where the common path of travel of the accessible route for access to the wheelchair spaces meets the requirements in Section 1024.8.

1007.2 Continuity and components. Each required accessible means of egress shall be continuous to a public way and shall consist of one or more of the following components:

1. Accessible routes complying with Section 1104.

2. Stairways within exit enclosures complying with Sections 1007.3 and 1019.1.

3. Elevators complying with Section 1007.4.

4. Platform lifts complying with Section 1007.5.

5. Horizontal exits.

6. Smoke barriers.


1. Where the exit discharge is not accessible, an exterior area for assisted rescue must be provided in accordance with Section 1007.8.

2. Where the exit stairway is open to the exterior, the accessible means of egress shall include either an area of refuge in accordance with Section 1007.6 or an exterior area for assisted rescue in accordance with Section 1007.8.

1007.3 Enclosed exit stairways.

An enclosed exit stairway, to be considered part of an accessible means of egress, shall have a clear width of 48 inches (1219 mm) minimum between handrails and shall either incorporate an area of refuge within an enlarged floor-level landing or shall be accessed from either an area of refuge complying with Section 1007.6 or a horizontal exit.


1. Open exit stairways as permitted by Section 1019.1 are permitted to be considered part of an accessible means of egress.

2. The area of refuge is not required at open stairways that are permitted by Section 1019.1 in buildings or facilities that are equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1.

3. The clear width of 48 inches (1219 mm) between handrails and the area of refuge is not required at exit stairways in buildings or facilities equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.

4. The clear width of 48 inches (1219 mm) between handrails is not required for enclosed exit stairways accessed from a horizontal exit. 5. Areas of refuge are not required at exit stairways serving open parking garages.

The IBC Egress code also includes 1007.4: Elevators, 1007.5 Platform Lifts and 1007.6 Areas of Refuge - all of which can be read in the document cited just below.

Stair Guardrail Specifications

Guardrail collapse led to injury (C) Daniel Friedman

Above: my sister, Linda Ann is demonstrating an attractie but really too-big-to-grasp newel post at the bottom of a stairway in Mexico.

Guards or guard rails referred to in stair codes and specifications refer to the safety barrier placed along the open sides of a horizontal walking surface such as a landing, balcony, deck, or porch.

Stair rails: the equivalent safety barrier placed along a stairway and called a stair rail is discussed at HANDRAILS & HANDRAILINGS

Quick definitions: What's the difference between a handrail and a guardrail?

Handrails are intended to be grasped to assist the user in climbing or descending the stairway and to help prevent a fall.

Guardrails are enclosures to prevent someone from falling through or off of a stairway, deck, balcony, etc.

Note that in most codes it is permitted to make the stair guard or stair rail graspable, making it also usable as a stair handrail. But if the stair rail is not graspable, a graspable handrail must also be installed.

Stair Railing Specifications - guards along stairways

 Railing too low to grasp (C) Daniel Friedman

Railings in stair codes and specifications refer to the safety barrier along steps or stairs.

Also see GUARDRAILS on BALCONIES, DECKS, LANDINGS for details about safety railings on landings and open hallways, porches, screened porches, balconies - horizontal walking surfaces.

Guards [guardrails] are required by section R316 for open sides of stairways, porches, balconies or raised floor surfaces located more than 30 inches above the floor or grade below, except for open sides of a flight of stairs with a total rise of 30 inches or less, although handrails are still required when there are two or more risers.

Guards protecting floor surfaces must be 36 inches in height, while guards for stairs must be 34 inches in height measured vertically from the tread nosing.

A guard may also serve as the required handrail (34 to 38 inches high) provided the top rail meets the requirements for grip size. The guard must have intermediate rails or ornamental closures that do not allow the passage of a 4-inch diameter sphere. The triangular openings formed by the riser, tread and bottom rail of the guard must be sized to prevent the passage of a 6-inch sphere.

Details about guardrails, handrails, and stair railings are at these articles:

Outdoor Guardrails - on Double Retaining Walls

Using a local building code citation from Glen Cove, New York, for outdoor double-retaining walls outdoors, the lower retaining wall is 48" in height, the space between the retaining walls is four feet or more, and the top of the wall is 24" high. -- Richard Kralstein

Stair Handrail Dimensions & Shape Specifications

Bad Stair Top Railing (C) Daniel Friedman

A handrail, unlike a stair rail or guard rail, must be graspable and is is defined as:

A horizontal or sloping rail intended for grasping by the hand for guidance or support.

Handrails have multiple requirements such as graspability, projection into the stairway, handrail height, & mechanical security rules.

Complete details about handrails such as those used along stairs and ramps are at HANDRAILS & HANDRAILINGS Excerpts are bleow.

Handrail cross section and size:

sketch of a proper handrail along a stairway - Canadian OSHA

Figure 4 (left) shows the recommended cross-section and dimensions of a good handrail. Ideally the cross-section should be round (diameter 4-5 cm, with circumference of 12-14 cm) to allow for a good firm grip.

You should be able to run your hand smoothly along the entire length without having to adjust your grip. You should apply the so-called "tennis-racket grip" at all times when possible.

Guardrails of at least 40 cm above the surface of the stairs are needed to prevent falls off the side of the stairs that are not equipped with a banister.

Details about safe graspable and unsafe non-graspable handrailings are found at GRASPABILITY of HANDRAILINGS.

[From Canadian Occupational Safety Regulations - Stairways & Fall Prevention, but this dimension and concept of graspability is widely used]

Clarification on Handrails and Guardrails: number of risers

Stairway Lighting requirements (C) Carson Dunlop AssociatesClarification from Residential exit doors, stairways, landings, handrails and guards [PDF] for New York:

RCNYS section R315 requires stairways having two or more risers to have at least one handrail, at a height of between 34 and 38 inches above the nosing.

There must be a clearance of at least 1 ½ inches behind wall mounted handrails. Handrails must be continuous from a point above the top riser to a point above the lowest riser of each flight of stairs.

This would allow a newel post to be attached to the face of the bottom riser, with half of its base resting on the bottom tread.


Exceptions to R315.1 involving newel posts are contained in the original ICC version of the code and have been issued as a clarification to the RCNYS and are effective as follows:


1. Handrails shall be permitted to be interrupted by a newel post at a turn.

2. The use of a volute, turnout or starting newel shall be allowed over the lowest tread.

The section of a stairway leading from one landing to the next is a flight of stairs. Therefore, handrails are not required on landings [though guardrails might be if the landing is open - Ed.].

Continuous handrails are required on the side of where the tread is narrower for winders. The maximum variation in riser height and tread width is 3/8 inches to maintain uniformity in the flight. Handrail grips may be circular, 1 ¼ to 2 inches in diameter.

If they are not circular the perimeter of the sides must total 4 to 6 ¼ inches with a maximum cross-section dimension of 2 ¼ inches.

When the total perimeter of the sides exceeds 6 ¼ inches, a graspable finger recess complying with section R315.2 must be provided on both sides of the handrail. There are no dimensional provisions for newels.

 Newel Post Tlaxcala (C) Daniel Friedman 2012

Above: a non-graspable railing along the top of a stair guard, Mexico City. The newel post at the landing is also sometimes used to arrest a fall.

Newel Posts for Stair Railings & Handrailings

This discussion has moved to newel POST CONSTRUCTION

Unsafe exterior stair stringer and riser height (C) Daniel FriedmanStair Step Risers - codes and specs

See details about stair risers

at STAIR RISER SPECIFICATIONS. A summary is just below

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.

The greatest step riser height within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm).

The 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. - 2007 NYS Stair Code: 1009.3 Stair treads

Stair Risers Open or Solid-Closed, Code Requirements

Stair tread dimensions (C) Carson Dunlop Associates

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.

Sketch courtesy Carson Dunlop Associates.


Details: see

Stair Stringer Codes & Specifications: required strength for stair supports

Stairway Lighting requirements (C) Carson Dunlop Associates

Details about the construction of & building code specifications for building stair stringers - the angled beam that supports stairs - are


For stair stringer defect inspection tips also


The notched stringer approach shown at left is very secure provided that the stringer depth is great enough and the cutout depth shallow enough that the remaining stringer material is strong enough to carry the weight of the stairway and its users (1-? arrow in sketch at left).

The stair stringer may also support stair treads using grooves routed into the stringer, or stairs may be butted into the inner face of the stringer and nailed or screwed through the stringer opposite side - a dangerous approach that risks stair collapse if additional measures are not taken.

Stair Tread Specifications

Worn unsafe stone steps, Hacienda Jaral de Berrio, Mexico (C) Daniel Friedman2007 NYS Stair Code: 1009.3 Stair treads

Shown in our photo: worn stone stair steps at the Hacienda Jaral de Berrio, Mexico.

These steps are a trip and fall hazard, increased by the absence of guard railings and handrails.

The graeatest stair tread depth within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm).

Winder treads shall have a minimum tread depth of 11 inches (279 mm) measured at a right angle to the tread's leading edge at a point 12 inches (305 mm) from the side where the treads are narrower and a minimum tread depth of 10 inches (254 mm).

The greatest winder stair tread depth at the 12-inch (305 mm) walk line within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm).

An exception to step riser height is permitted at joining a sloping surface

Where the bottom or top riser adjoins a sloping public way, walkway or driveway having an established grade and serving as a landing, the bottom or top riser is permitted to be reduced along the slope to less than 4 inches (102 mm) in height with the variation in height of the bottom or top riser not to exceed one unit vertical in 12 units horizontal (8-percent slope) of stairway width.

The nosings or leading edges of treads at such nonuniform height risers shall have a distinctive marking stripe, different from any other nosing marking provided on the stair flight.

The distinctive marking stripe shall be visible in descent of the stair and shall have a slip-resistant surface. Marking stripes shall have a width of at least 1 inch (25 mm) but not more than 2 inches (51 mm).


Stair Tread Specifications

Stair tread dimensions (C) Carson Dunlop Associates

Stair Step Treads

Step tread depth (=> 10") (measured 12" from smaller side of irregular stair shapes such as triangular treads on curves or spirals) [Stair tread depth is the horizontal distance from the nose of the tread to the back edge of the tread (where a vertical riser or open space may be found).

Details about stair step tread codes and specs

Thick wooden stair treads, Campo San Maurizio Venice Italy (C) Daniel Friedman at InspectApedia.comThe steep, thick wooden-tread stair shown here, located in Campo San Maurizio, Venice Italy, are old, creaky, and steep with minimal hand-rail, no top landing, and a too-short landing as shown in our photo. This stairway is what can fit in the available space.



A summary of permissible stair tread or landing walking surface slope is below

Reader comment on variation in stair tread slope:

[The above specification of allowable variation in stair tread slope] was probably taken from the chapter on Means of Egress, in which case it is applicable to a means of egress, and not stairs outside the means of egress, like in a public way. It is very hard to maintain such tolerances for exterior sidewalks and public ways.

At least I think that is the way it is in the IBC. I am not a code official, however, and I know they may see things differently. - J.M., AIA

Reply: the above discusses stair treads and does not refer to sidewalks - Ed. CONTACT us to suggest building code citations or stair tread specifications that vary from these.

Also see STAIR TREAD SLOPE where we discuss slip hazards.

2008 New York State Stair Code R311.5.3.2: Tread depth.

Another Stair Code Example - Source BOCA 2001 stair construction code details:

Details about tread construction for outdoor stairs include opinions about avoiding cupping and slippery ice or algae:


Stair Step Tread Nose Specifications

Stair tread nose damage, trip and fall hazard © D Friedman at Details about the proper design of stair tread nosings in shape & dimensions as well as history, research & stair tread nose hazard discussion are


A summary is below

1009.3.2 Profile. The radius of curvature at the leading edge of the tread shall be not greater than 0.5 inch (12.7 mm).

Beveling of nosings shall not exceed 0.5 inch (12.7 mm). Risers shall be solid and vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 degrees (0.52 rad) from the vertical.

The leading edge (nosings) of treads shall project not more than 1.25 inches (32 mm) beyond the tread below and all projections of the leading edges shall be of uniform size, including the leading edge of the floor at the top of a flight.

Reader question: is this doubled stair tread nose acceptable?

I am looking for information on stair noses. I am having hardwood flooring installed in a home that previously had carpet and vinyl.

The stairs are pine that previously had carpet installed over them and were not finished at all.

The current hardwood floor installer has installed the top stair bullnose, that ties into the upstairs flooring, right over the existing bullnose so that two rounded edge bullnoses are visible.

The installer refuses to trim the nose flush to the riser so that only one bullnose is visible stating that trimming the nose/lip would effect the integrity of the stairs. To confirm this is only the top stair that ties into the floor. It looks very bad aesthetically.

Is this common practice? There are numerous videos and periodicals showing proper installation would be to trim the existing lip. Please help. - Anon by private email 2017/10/30

Unsafe double-tread means double nose on stair treads (C) CW

Reply: no.

While building codes cannot anticipate every possible way that a stair-builder can foul up a set of stairs, in our OPINION the stair tread nose shown below is a trip hazard, principally because of its double thickness.

The stair tread double-nose photograph above, provided by the reader, appears to violate the stair tread nose curve radius and stair tread nose profile (greater than 1/2-inch).

A double-thick stair tread nose may catch the tip of a shoe, particularly when ascending the stairway. In my vew these treads need to be repaired.

I would trim back the under-tread to flush with the riser face - a job taht would have been easier before the top level of flooring was installed (and may be a too-thin tread nose).

Watch out: if the double layer of walking surface was installed only on the topmost step (the floor) then the riser heights of these stairs may also be inconsistent by 3/4" at the topmost step - another trip and fall hazard.

2008 New York State Stair Code R311.5.3.3: Stair Tread [nose] Profile.

The radius of curvature at the leading edge of the [stair] tread shall be no greater than 9 / 16 inch (14.3 mm). A nosing not less than 3/4 inch (19 mm) but not more than 1 1/4 inch (32 mm) shall be provided on stairways with solid risers.

The greatest [stair tread] nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings.

Beveling of [stair tread] nosing shall not exceed 1 / 2 inch (12.7 mm). Risers shall be vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 (0.51 rad) degrees from the vertical.

Open risers are permitted, provided that the opening between treads does not permit the passage of a 4-inch diameter (102 mm) sphere.

Exceptions [to stair tread nose requirements]:

(Courtesy Arlene Puentes).

Another Stair Code Example of stair tread nose profile and projection - BOCA 2001.

Reader Question: are stair tread nose projections actually a trip hazard?

5/22/2014 Ian McIlvaine said:

My father-in-law has tripped several times on his stairs and blamed the protruding nosing.

He asked me why stairs have nosings and I had to confess that I didn't really know. I did some research on tripping and protruding nosings and found that the Australian code does not allow open risers or protruding lips/nosings on stair treads precisely because they are a trip hazard for the disabled.

It is interesting, then, that this article mentions that a stair MUST have a protruding nosing of min. 3/4" to max. 1-1/2". Can anyone explain why this is so when such a lip can so easily catch a toe of someone climbing a stair?

Reply: research on stair tread nose hazards

For space and ease of discussion we've moved this topic to its own article found at


Stair Tread Slope, Drainage, & Stair Tread Anti-Slip or Coefficient of Friction Requirement for Safe Walking Surfaces

1009.5.1 Stairway walking surface. The walking surface of treads and landings of a stairway shall not be sloped steeper than one unit vertical in 48 units horizontal (2-percent slope) in any direction. Stairway treads and landings shall have a solid surface. Finish floor surfaces shall be securely attached.

Exception: In Group F, H and S occupancies, other than areas of parking structures accessible to the public, openings in treads and landings shall not be prohibited provided a sphere with a diameter of 11/8 inches (29 mm) cannot pass through the opening.

Relevant to the slipperiness of stairs is this outside stair provision

1009.5.2 Outdoor conditions. Outdoor stairways and outdoor approaches to stairways shall be designed so that water will not accumulate on walking surfaces.

In other than occupancies in Group R-3, and occupancies in Group U that are accessory to an occupancy in Group R-3, treads, platforms and landings that are part of exterior stairways in climates subject to snow or ice shall be protected to prevent the accumulation of same.

[Not found in NYS Code] - A walking-surface that provides a coefficient of friction of 1.02 dry and 0.98 wet will comply with ADA, OSHA, and most local building codes and insurance requirements. This requirement is reiterated in our summary of Canadian OSH stairway rules below.

Details about stair slip and trip hazards due to walking conditions are at

Stairway Slope or Angle Specifications

Stringer slope determines overall slope of the stair assembly

While individual stair riser heights and tread dimensions determine the walking comfort and safety of stairs and stairways, here are some typical overall slope specifications that characterize different types of building entrances and exits.

You can see from the sketches below the recommended range of slopes or angles for various types of ramps, stairs and ladders.

Stair dimensions

From: Kodak's ergonomic design for people at work. 2nd ed. John Wiley & Sons, 2004. p.24

Stair Dimensions


Stair Platform or Landing Specifications

Stairway Lighting requirements (C) Carson Dunlop Associates

Stair Landings are required at top and bottom (with exceptions at top of interior stairs or in garage if door swings in, away from the stairs)

See details about stair landing codes and specifications

at STAIR PLATFORMS & LANDINGS, ENTRY. A summary is below.

Examples of Stair Platform or Landing Defects

Sketch courtesy Carson Dunlop Associates.

1009.4 Stairway landings. There shall be a floor or landing at the top and bottom of each stairway.

The width of landings shall not be less than the width of stairways they serve. Every landing shall have a minimum dimension measured in the direction of travel equal to the width of the stairway. Such dimension need not exceed 48 inches (1219 mm) where the stairway has a straight run.

Clarification from Residential exit doors, stairways, landings, handrails and guards [PDF] for New York:

Section R312 requires a floor or landing at the top and bottom of each stairway and on each side of each exterior door. The exception provides that on all exterior doors, except the required main exit door, where there are two or fewer risers, a landing is not required.

Section R312.1.2 also provides that at the required main exit door, the landing be no more than 1 ½ inches lower than the top of the threshold, while landings at all other exterior doorways may be as much as 8 ¼ inches lower than the threshold.

However, the State Fire Prevention and Building Code Council amended this section in 19 NYCRR section 1220.3, effective July 10, 2003, as follows:

Landings at required exit doors. In lieu of compliance with section R312.1.2 of the Residential Code of New York State, an exit door required by section R311.1 of the Residential Code of New York State may have an exterior landing which is not more than 8 ¼ inches (209 mm) below the top of the threshold.

With this amendment, there is no longer a requirement that the level of the landing outside the required main exit door be limited to no more than 1 ½ inches below the threshold. Additionally, landings have to be at least as wide as the door or stairway and at least 36 inches long measured in the direction of travel.

And from the same document

Landings are required on the exterior side of a sliding glass door when served by a stair having more than two risers. A 6-0 x 6-8 sliding door (even if it is an emergency escape and rescue opening required in a sleeping room) is still a door and requires a landing per section R312.1.2.

Considering only the operable part of the sliding door, the width of the landing does not need exceed 36 inches. It would also be permitted to install a guard on the exterior of the sliding door in lieu of the required landing and stairs when the door threshold is more than 30 inches above grade.

Building Code for Stairway Lighting Requirements

Stairway Lighting requirements (C) Carson Dunlop Associates

Stairway Lighting is Required, with light switches at top and bottom of the stairway if the stairs encompass more than three stair treads (Canada) or six stair treads (U.S.).

Details about lighting requirements and codes for lighting requirements over stairs are at

Sketch courtesy Carson Dunlop Associates.

Stairway Width, handrail height, handrail projection specifications

Clarification from Residential exit doors, stairways, landings, handrails and guards for New York:

Stairways are regulated by section R314 and include winders, spiral stairs, circular stairs, and bulkhead enclosure stairs.

Stairways shall be not less than 36 inches in clear width at all points above the handrail height and the handrail may project no more than 4 ½ inches on either side of the stairway.

Thus, the minimum clear width of a stairway at or below the handrail, when one is required, is 31 ½ inches, and 27 inches where two are required. Stair trim, stringers and other features may reduce the stairway width as long as they do not extend beyond the allowable handrail projection.

There is a width exception for spiral stairways. The maximum riser height is 8 ¼ inches and the minimum tread depth is 9 inches.

Open risers are permitted provided the vertical opening between treads does not permit the passage of a 4-inch-diameter sphere in stairways which have a rise exceeding 30 inches.

The minimum headroom is 6 feet, 8 inches measured vertically from a sloped plane along the tread nosings or from the floor or landing surface.

Details are


Exceptions may be at ATTIC STAIR CODES & HAZARDS and

at BASEMENT STAIRS depending on how these areas are used or intended to be occupied.

Code Specifications for Stairs that are Angled, Curved, Circular, Spiral, or Winder Stairs

Stairway Lighting requirements (C) Carson Dunlop Associates

Sketch at above right, courtesy Carson Dunlop Associates.

Angled stairs in Manhattan (C) Daniel Friedman

Details about circular, spiral, and winder stairs and their code & construction requirements are at

Alternating Tread Stair Definition & Codes

Alternating tread stairway, Pearson-Murphy Guanajuato (C) Daniel Friedman

Definition of Alternating Tread Stairs or "Devices:

A device that has a series of steps between 50 and 70 degrees (0.87 and 1.22 rad) from horizontal, usually attached to a center support rail in an alternating manner so that the user does not have both feet on the same level at the same time. - IRC R-202 - [14a]

1009.10 Alternating tread devices. Alternating tread devices are limited to an element of a means of egress in buildings of Groups F, H and S from a mezzanine not more than 250 square feet (23 m2) in area and which serves not more than five occupants; in buildings of Group I-3 from a guard tower, observation station or control room not more than 250 square feet (23 m2) in area and for access to unoccupied roofs.

Shown above: alternating tread stairs used to access a rooftop utility area, Guanajuato, Mexico. Courtesy D.P. & L.M.

Scissors Stairways Defined

Definition of a Scissors Stair:

Two interlocking stairways providing two separate paths of egress located within one stairwell enclosure - IBC 1002 [14a]

Scissors stairways may be installed to avoid crowding or safety issues between people ascending and descending between building floors - where you may see an UP staircase marked separately from a DOWN staircase.

Stairway Height, Width, Headroom Code Specifications & Requirements

Stairway Lighting requirements (C) Carson Dunlop AssociatesStairway headroom (=> 6'8" over tread or landing)

Stairways shall have a minimum headroom clearance of 80 inches (2032 mm) measured vertically from a line connecting the edge of the nosings.

Such headroom shall be continuous above the stairway to the point where the line intersects the landing below, one tread depth beyond the bottom riser.

The minimum clearance shall be maintained the full width of the stairway and landing. - NYS

Headroom is allowed to be reduced to 78" over spiral stairs in some codes such as New York State.

Details are at STAIR HEADROOM

Sketch showing stairwell width and landing details is provided courtesy Carson Dunlop Associates.

Stairwell width and stair landing platform requirements are summarized by this sketch.

The minimum recommended stair width is between 34" and 36" ACROSS.

The minimum recommended stair landing length is 36" (or a length and width sufficiently greater than the swing of the door if a wider door is present.

Notice that a stair top landing is not required if the door at the top of the stair opens away from the stairwell.

In these sketches required handrails have been omitted for clarity.

1009.1 Stairway width. The width of stairways shall be determined as specified in Section 1005.1, but such width shall not be less than 44 inches (1118 mm). See Section 1007.3 for accessible means of egress stairways.

Maximum Permitted Height for Stairways - between floors or landings

1009.6 Vertical rise. A flight of stairs shall not have a vertical rise greater than 12 feet (3658 mm) between floor levels or landings.

This means that if the floor to floor height traversed by a stairway is more than 12 feet of vertical distance, one or more landings is required.

Stairway Fire Stopping Code Requirements

Stairway Lighting requirements (C) Carson Dunlop Associates

Fire stopping for stairs is required to slow the spread of building fires between floors and to assist in emergency exit.

Sketch courtesy Carson Dunlop Associates, a Toronto home inspection, report writing & education company.

Notes Comparing Building Codes Specifying Stair & Railing Requirements         

Sample excerpts of sources which a building code compliance inspector would be expected to cite in support of requiring a properly-designed, properly-secured guard rail include but are not limited to the citations below.


Building Codes, including Full Text Copies of Model Building Codes & Local Codes

This list has moved to BUILDING CODE DOWNLOADS

In the REFERENCES section of this article you will find more model codes and other key documents on building codes and stair and railing safety.


Continue reading at BUILDING CODES for STAIRS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see CODES for STAIRS & RAILING, FAQs - questions and answers about stair and railing codes and standards posted originally at this article

Or see BUILDING CODE DOWNLOADS - free downloadable PDF files of building codes & standards

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CODES for STAIRS & RAILINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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