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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.

Having investigated cases of severe injury related to falls and railing collapses we developed this field data collection checklist. We also include references to key documents on building codes and stair and railing safety. DECK COLLAPSE Case Study describes a catastrophic exterior deck collapse.

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

Below we illustrate and summarize typical building code requirements for stairs, railings, landings, and guardrails. Links at page left 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.

Stairway, Railing, Landing Basic Dimensions & Rules

Stair Guardrail, Newell Post & Baluster Specifications

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. The equivalent safety barrier placed along a stairway itself is discussed at >Railings.

Balusters for Guards & Railings

Stair Railing Specifications

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

Stair Riser Specifications

Stair Tread Specifications

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).
• 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

2008 New York State Stair Code R311.5.3.2: 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:

• 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 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.

Stair Step Tread Nose

• 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

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]:

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

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

• Stair tread nose projection missing or wrong dimension: (falling hazard on descending) or tread nose extends out too far over tread (risk splitting off or trip on climbing up). Example: A nosing not less than 0.75 inch (19.1 mm) but not more than 1.25 inches (32 mm) shall be provided on stairways with solid risers where the tread depth is less than 11 inches (279 mm). - BOCA 2001.

Stair Platform or Landing Specifications

Building Code for Stairway Lighting Requirements

Code Specifications for Stairs that are Curved or Angled, & Winder Stairs

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.

2008 New York State Residential Building Code Stair Design Specifications:

This building code update for stairway design specifications was provided courtesy Arlene Puentes.

R311.5.3.1 Riser height.

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).

R311.5.3.2 Tread depth.

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).

R311.5.3.3 Profile.

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:

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

R311.5.8.1 Spiral stairways.

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.

International Building Code 2000 (BOCA, ICBO, SBCCI)

1003.3.3.4 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.

1003.3.3.11.3 Handrail grasp ability. 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 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. 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 Components. 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.

BOCA National Property Maintenance Code 1993:

PM-305.5 Stairs and railings: 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.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

STAIRS, RAILINGS, LANDINGS, RAMPS
  Attic stairs
  Balusters & Railing Enclosures
  Basement Stairs & Walkout Covers
  Books on Stair Construction
  Checklist for Stair Inspections
  Codes for Stairs
  Exterior stairs
  Fire Stopping for Stairways
  Guardrails on Balconies & Landings
  Lighting over Stairs
  Railings on Stairways
  Ramps, access
  Stair dimensions: width height &c
  Stairway headroom
  Stairway landings
  Step riser dimensions
  Step stringer defects
  Step tread dimensions
  Stair tread nose dimensions
  Winder stairs

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Arlene Puentes, 845-339-7984, is an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at ap@octoberhome.com.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• "The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
• "Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
• Slips, Trips, Missteps and Their Consequences, Second Edition, Gary M. Bakken, H. Harvey Cohen,A. S. Hyde, Jon R. Abele, ISBN-13: 978-1-933264-01-1 or ISBN 10: 1-933264-01-2, available from the publisher, Lawyers ^ Judges Publishing Company,Inc., www.lawyersandjudges.com sales@lawyersandjudges.com and also from the InspectAPedia Bookstore (Amazon.com)
• The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code.
• The following stair books and other books on stair history, design, and architecture can be purchased at our Amazon-Supported InspectAPedia Bookstore
• Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
• The Staircase: History and Theories, John Templar, MIT Press 1995
• The Staircase (two volumes), John Templar, Cambridge: the MIT Press, 1992.
• "The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
• ...

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