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This document lists 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.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Newell posts in stairways are more than decorative and are often grasped or leant-upon as you can see in this photo(left) from Tlaxcala, Mexico. The enclosed masonry stair guard being rested upon by the tourists is certainly at adequate height and strength; a graspable handrailing was installed on the opposite side of the stairway.
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.
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
See RAILINGS, DECK & PORCH where we provide deck, porch, and retaining wall safety railing design and building code details. There we cite several building codes that require safety railings at outdoor retaining walls, and we express the opinion that seating or a "seat wall" does not provide the equivalent safety as a properly constructed railing.
Also see Exterior stairs.
Balusters for Guards & Railings
Stair Railing Specifications - guards along stairways
Railings in stair codes and specifications refer to the safety barrier along steps or stairs. Also see Guards for details about safety railings on landings and open hallways, porches, screened porches, balconies - horizontal walking surfaces.
Stair Handrail Dimensions & Shape Specifications
Clarification on Handrails and Guardrails
Clarification from Residential exit doors, stairways, landings, handrails and guards for New York:
An exception to step riser height is permitted
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 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.
Details about stair step tread codes and specs are at STAIR TREAD DIMENSIONS. A summary is below
[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
Note: 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 Stair Tread Slope below
2008 New York State Stair Code R3188.8.131.52: Tread depth.
The minimum [stair] tread depth shall be 9 inches (229 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).
Winder treads shall have a minimum tread depth of 10 inches (254 mm) measured as above at a point 12 inches (305) mm from the side where the treads are narrower. Winder treads shall have a minimum tread depth of 6 inches (152 mm) at any point. Within any flight of stairs, the greatest winder tread depth at the 12 inch (305 mm) walk line shall not exceed the smallest by more than 3/8 inch (9.5 mm). (Courtesy Arlene Puentes).
Another Stair Code Example - Source BOCA 2001 stair construction code details:
Details about stair step or tread nose specifications are at Stair tread nose dimensions. 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.
2008 New York State Stair Code R3184.108.40.206: 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]:
A nosing is not required where the tread depth is a minimum of 11 inches (279 mm). >
The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less(Courtesy Arlene Puentes).
Another Stair Code Example of stair tread nose profile and projection - BOCA 2001.
Clarification of Stair width, handrail height, handrail projection, stairway width
Clarification from Residential exit doors, stairways, landings, handrails and guards for New York:
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 Algae, Ice, Fungus, Wet Surfaces & Other Stair Slip, Trip & Fall Hazards. Also see Exterior Stair Falls for a catalog of causes of falls on stairs that includes surface conditions and other defects.
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 for New York:
And from the same document
Sketch at above right, courtesy Carson Dunlop Associates.
Details about circular, spiral, and winder stairs and their code & construction requirements are at CIRCULAR & CURVED STAIRS
Alternating Tread Stair Definition & Codes
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.
Definition of Alternating Tread Stairs or "Devices:
Open or Closed Stair Tread Codes
Definitionof Scissors Stair:
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.
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
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 building code update for stairway design specifications was provided courtesy Arlene Puentes.
R3220.127.116.11 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).
R318.104.22.168 Stair Tread Depth Code Requirements
The minimum tread depth shall be 9 inches (229 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge.
The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3 / 8 inch (9.5 mm). Winder treads shall have a minimum tread depth of 10 inches (254 mm) measured as above at a point 12 inches (305) mm from the side where the treads are narrower.
Winder treads shall have a minimum tread depth of 6 inches (152 mm) at any point. Within any flight of stairs, the greatest winder tread depth at the 12 inch (305 mm) walk line shall not exceed the smallest by more than 3 / 8 inch (9.5 mm).
R322.214.171.124 Stair Tread Nose Profile Code Requirements
The radius of curvature at the leading edge of the 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 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 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:
1. A nosing is not required where the tread depth is a minimum of 11 inches (279 mm).
2. The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less
Stair Tread Anti-Slip or Coefficient of Friction Recommendations for Safe Walking Surfaces
[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. Other sources (cited in the two articles listed just below) cite a coefficient of friction of 0.5 (OSHA) or 0.6 (ADA) as the minimum recommended COF to avoid slippery walking surfaces and stairways.
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.
R3126.96.36.199 Spiral Stairway Building Codes
Spiral stairways are permitted for interior use as a component of the means of egress from a habitable room, a basement or an attic, provided the minimum width shall be 26 inches (660 mm) with each tread having a 7 1 / 2 -inch (190 mm) minimum tread depth at 12 inches from the narrower edge.
All treads shall be identical, and the rise shall be no more than 9 1 / 2 inches (241 mm).
A minimum headroom of 6 feet 6 inches (1982 mm) shall be provided. A spiral stair is not permitted to be the only means of egress from a story of a building.
1003.3.3.4 Stairway Landing Codes
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.
1003.3.3.11.3 Handrail Grasp Ability (Graspability) Requirements
Our photo (left) illustrates the author (DF) holding on to a secure, graspable handrail in a building in Bar Harbor, Maine. Also see
Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent grasp ability.
If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (159 mm) with a maximum cross-section dimension of 2.25 inches (57 mm). Edges shall have a minimum radius of 0.125 inch (3.2 mm).
100333.11.4 Handrail or Guardrail Continuity
Handrail-gripping surfaces shall be continuous, without interruption by newel posts or other obstructions.
1607.7 Loads on Handrails, guards, grab bars and vehicle barriers
1607.7.1.1 Concentrated Load on Railings
Handrail assemblies and guards shall be able to resist a single concentrated load of 200 pounds (0.89kN), applied in any direction at any point along the top, and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building.
1607.7.1.2 Component of Railings and Guardrails
Intermediate rails (all those except the handrail), balusters and panel fillers shall be designed to withstand a horizontally applied normal load of 50 pounds (0.22 kN) on an area not to exceed one square foot (305mm2) including openings and space between rails.
PM-305.5 Stairs and Railings in Good Condition
all interior stairs and railings shall be maintained in sound condition and good repair.
Commentary: Handrails, treads and risers must be structurally sound, firmly attached to the structure, and properly maintained to perform their intended function safely. During an inspection the code official should inspect all stringers, risers, treads, and handrails.
PM-305.6 Handrails and guards
Every handrail and guard shall be firmly fastened and capable of supporting normally imposed loads and shall be maintained in good condition.
Commentary: This section provides for the safety and maintenance of handrails and guards. See Section PM-702.9 for additional requirements.
PM-702.9 Stairways, handrails and guards
Every exterior and interior flight of stairs having more than four risers, and every open portion of a stair, landing or balcony which is more than 30 inches (762mm) high, nor more than 42 inches (1067mm) high, measured vertically above the nosing of the tread or above the finished floor of the landing or walking surfaces. Guards shall be not less than 30 inches (762mm) high above the floor of the landing or balcony.
Commentary: Handrails are required on all stairs more than four risers in height. Handrails cannot be less than 30 inches nor more than 42 inches above the nosing of the treads (see Figure PM-702.9).
Guards are required on the open side of stairs and on landings and balconies which are more than 30 inches above the floor or grade below. The guard must be at least 30 inches above the floor of the landing or balcony. Guards are to contain intermediate rails, balusters or other construction to reduce the chance of an adult or child from falling through the guard. If the guard is missing some intermediate rails or balustrades, it is recommended that the guard be repaired to its original condition if it will provide protection equivalent to the protection it provided when originally constructed.
STAIRWAYS - see OSHA at references
OSHA Regulations for Stair Railings & Guardrails
STAIRRAILS AND HANDRAILS
Why do we need to worry so much about falls on stairs?
Stairs of all types have been used since ancient times, and because they are inherently hazardous, people have been falling on them, getting hurt or even killed in the process. In North America tens of people die and tens of thousand people get injured every year from the falls on stairs. The American National Council on Compensation Insurance estimated in 2001-2002 that the cost of such fall injuries was second only to those caused by motor vehicles.
The vast majority of stairway falls result from a loss of balance, just as falls are on the level. Please see the Canadian OSH Answers document on Prevention of Slips, Trips and Falls.
A very common contributing factor is neglecting to use handrails. The consequences can be quite nasty.
Because stairway accidents can cause severe injury and even death, building codes for stairs and ramps are justifiably very rigorous. Good design can substantially reduce the potential for mis-stepping by providing us with the means to retrieve our balance, but even the best design cannot eliminate falling hazards entirely. The need for proper design also applies to ramps. The fact is that some incidents can be caused by inattention and unsafe behaviour.
The best approach to minimize the hazard of falling down stairs is to encourage the building of well-designed stairways, combined with training focused on raising our awareness of the potential for disaster.
What factors must we consider in designing safer stairs?
Stair dimensions - Canadian Rules
From: Kodak's ergonomic design for people at work. 2nd ed. John Wiley & Sons, 2004. p.244
The dimension of risers or treads in a stairway should not vary more than 1 cm. When doors open directly into the stairwell, a 50 cm-wide platform should be provided beyond the swing of the door. The recommended maximum number of steps between landings is 18, with no more than two flights without a change of direction. The depth of any landing should be at least equal to the width of the stairs.
Stair surface - Canadian Rules
To reduce the risk of slipping on stairs, non-slippery surface on the whole steps or at least on the leading edges is crucial. Such a surface can be made of rubber, or metal or painted with special slip-resistant paint. Regular maintenance of the stairs in good repair plus good housekeeping can reduce hazards for tripping.
Stair handrails - Canadian Requirements
Attempts to design aesthetically pleasing stairways including handrails must not compromise functionality.
The prime function of the handrail is for holding as support while going up or down stairs.
It is therefore crucial to be able to grasp it quickly, easily and firmly if you should start losing your balance.
Visibility on stairs
Improving visibility on stairs significantly reduces the risk for common mishaps caused by misjudging distances. Otherwise you can trip on a step or miss it completely. You can catch a heel on the edge of a step. Such mishaps are a routine cause of twisted ankles, sprained knees or more serious injuries incurred by a total fall.
Work activity on stairs
Good housekeeping is also vital to stair safety:
Frequently Asked Questions (FAQs) about stair codes, design, construction, & safety
Question: Is the final stair rise from top thread to threshold of building considered a riser?
We have a back door onto a slab 4" patio. The door's threshold is ~20" above above grade. The slab is continous up to the house. Building a concrete stairway/flight to code will require 2 treads, to reach the threshhold.
Is the final rise from the top tread to the treshhold considered a riser, even though the stairway/flight has no such riser? To make the question more understandable, you build a stairway/flight and then position it against the house. If the elevation from the top tread to the threshhold considered a riser?
Also, is a footing required, even though the stairway/flight is on a 4" concrete slab? - dansbysa
Question: is an exception to step riser height uniformity allowed when using pre-fab stair stringters?
Is there an exception to the riser height variation for the very first step of the staircase? Let me attempt to clarify the question. I have a deck (exterior porch) for which the distance from the top of the deck to the slab which forms the footing for the set of stairs is just shy of the 5 steps within a pre-fabricated 5 step stair stringer which can be purchased at a Home Depot or Lowes, for example.
If I attach the pre-made stringer from the deck to the slab, ensuring that the top of the deck to the next stair down is the same height as the rest, then the riser height from the slab to the first stair is greater than a 3/8" variation from the rest of the riser heights by 1/8th of an inch (ie. it's 1/2 inch shorter than the rest of the stairs - I actually need to remove a half inch from the bottom most stair of the stringer to fit). If this is a violation of code, than it means I need to cut my own customer stringer. Just verifying. Any feedback is appreciated. - Dan
Reply: In short, no, but in this case you can adjust the stringer to meet code
Dan we answered this question previously in detail at Step riser dimensions - please take a look at that article. In short, because your step riser height variation at the first step is 1/2" shorter than the rest of the stairs, you can trim the top and bottom of the stair stringer to split that difference, making sure that the variation in step riser height is 1/4" or less - which meets code.
Question: stair weight capacity requirements: stair load design specifications
Is there a minimum weight capacity for wooden stairs? - Hendrick
Hendrick: regarding stair load capacity, the best answer is to start by asking your local building department - the local code officials are the final authority on stair load capacity requirements.
Question: do I need to remodel stairs in a 1979 rental cabin to comply with current building codes
I purchased a cabin recently, the cabin was built in 1979, at that time the building code for stairs was different than the code today. I do rent the cabin. Do I need to remodeled the stair to be conform to the new building codes? - Mike Jones
Reply: requirement to update stairs to meet current building codes: no, sometimes yes, but ...
Mike, re: requirement to update stairs to meet current building codes:
While the final answer to your question is in the hands of your local building department, usually building owners are not required to change or update their building to keep up with building code updates.
In my OPINION, because stair falls are the greatest source of injuries and hospitalizations in North America after automobile accidents, it is worth making stairs, railings, landings, and guardrails as safe as possible. You didn't mention anything specific about your cabin stairs, but certainly as a landlord, renting the property, you have an extra level of responsibility to your tenants to make the building safe, and you certainly don't want someone to be injured. I'd be sure to pay attention to basic trip and fall hazards such as uneven risers or treads, and inadequate railings.
Question: Elecrical boxes intalled in stairway in the walking path - hazards and stair fall, injury report
Questions & answers or comments about the design requirements and code specifications for building stairs, landings, railings, and guard railings.
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Technical Reviewers & References
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