A Complete Standards Guide for Interior Staircases in Public and Residential Spaces

1.       INTRO

If I could sum up all of architecture into one element, it would be the staircase: fundamentally functional and packed full of poetic potential. These dynamic circulation devices provide a building with opportunities for drama, perspective or simply a sculptural celebration.

However, like all things in architecture, our creativity is restricted by the laws of the real world. We can quickly lose inspiration in the mundanity of regulations and building codes. This article sums up globally recognized standards for residential and public building staircases, providing a solid reference so that you can focus on the poetry.  

Codes covered here are the IBC (International Building Code), ISO 21542 (Accessibility to the Built Environment), ADA (Americans with Disabilities Act), UK Part K/M (Building Regulations for Stairs & Access) and SIA 500 (Swiss Accessibility Standards).

2.       ANATOMY OF A STAIRCASE

Different terminology is sometimes used in different regions of the world and to avoid confusion, this section provides a recap of the fundamental “staircase anatomy”.  While most terms are best captured in the diagrams below, certain terms require some detailed explanation:

Balustrade: The collective term for the railing system on the side of a staircase, including the handrail, balusters, and posts.

Flight: A flight of stairs conventionally refers to a continuous set of uninterrupted steps between landings or floors.

Going: The horizontal distance between the front edges (nosings) of two consecutive steps.

Guardrail: A safety barrier along the open sides of stairs, landing or balconies to prevent falls. Guardrails are not always associated with staircases.

Slope / gradient / pitch: the angle or steepness of the stairs, determined by the ratio between the rise and tread, affecting both comfort and safety. Regulations for this value vary by region and application.

Springing point: The location where the incline of a staircase or handrail begins.

Staircase: The physical structure and system of stairs, including landings and balustrades.

Stairway: A passage or way consisting of a series of steps that connect different floors. The emphasis being on the route, not the structure.

Step formula: A widely accepted guideline in staircase design is the equation 2R + T = 600–630 mm, where R represents the riser height and T the tread depth. This formula ensures a comfortable and safe stair by aligning with the natural walking rhythm of an average person.

Stringer: The inclined support structure on the sides or middle of a staircase that holds the treads and risers.

Visual contrast: the use of distinct colors or materials on edges and nosings to enhance visibility and prevent trips or falls.

Wayfinding aid: tactile, visual, or auditory features designed to help users identify stair locations, changes in level, and safe pathways for easier and safer navigation.

Winder: A winder is a stair tread that is wider at one end than the other, used to allow a staircase to change direction without a landing. The tread width (T) is measured at the center.

3.       RESIDENTIAL STAIRCASES

Since homes usually serve only a small group of people, regulations are generally more flexible than for public spaces. For example, in most codes open risers are permitted and only a single handrail (or even just a barrier from falling, i.e. a wall) is mandatory.  Often narrower staircases are permitted with a steeper slope.

Fun fact: In many cases in traditional Dutch houses, especially in cities like Amsterdam, the staircases can be extremely steep and narrow to maximise usable space in small canal houses. These proportions make moving furniture impossible, so buildings are fitted with external hoists to allow furniture to come in through the window.

However, the key for contemporary staircase design is to provide comfort and practicality which needs to also include people with disabilities. The image below provides best practice dimensions that will satisfy most codes.  

Lighting is important for comfortable and safe movement along staircases. In residential settings, a combination of task lighting and ambient lights for a minimum of 11 lux should provide an even illumination along staircases and landings. Consider wall-mounted fixtures at each landing to avoid shadows and ensure safety.

Handrails should be continuous, graspable, and installed on at least one side of the stair (preferably both), with a height between 865–965 mm (34–38 in.) depending on the code. They should extend slightly beyond the top and bottom of the flight and return to the wall to prevent clothes or bags getting caught. Round or oval handrails of 32-52mm diameter (1.25-2in.) are the easiest to grip.

Stair materials should be durable, non-slip, and consistent with the home’s aesthetic—wood, metal, or concrete are common choices, but safety is paramount, so surfaces should have sufficient grip and avoid overly glossy finishes.

The table below offers more details about the specific requirements for different codes for residential staircase design. 

RESIDENTIAL STAIRCASE REGULATIONS BY CODE

4.       PUBLIC STAIRCASES

Public stairs are designed to serve larger groups of people at any one time and need to be functional to a wider range of users (all ages and abilities). Regulations around public stairs tend to focus on safety and security. Stairs that serve multiple residential units, such as those in apartment buildings, must satisfy the requirements for public staircases.  

Public stair width should accommodate expected traffic flow and meet code requirements—generally, a minimum of 1.2 meters (about 4 feet) is recommended, but wider stairs may be needed in high-occupancy areas for safe and comfortable movement.

Lighting in public stairs must always ensure safety and visibility. Use a uniform lighting strategy to provide a minimum of 11 lux, with bright fittings that are water-resistant if outside. Emergency backup systems are sometimes incorporated to maintain visibility during power outages.

Public stairs often serve as emergency routes which must be clearly marked, unobstructed, fire-rated, and lead directly to a safe area. Remember to check the local building fire codes for regulations that might restrict the design of a staircase.  

Handrails on public stairs should be provided on both sides, be continuous and easy to grip, and comply with accessibility standards (such as having extensions and proper clearances) to support users of all abilities.

The recommended height for children's handrails is 710 mm (28 in.), while standard adult handrails are typically installed at 865–965 mm (34–38in.) above the stair tread nosing. Ideally, both heights should be provided to accommodate users of different sizes.

Public stair materials must be hard-wearing, slip-resistant, and easy to maintain. Stone, concrete with anti-slip inserts, or treated metal are common choices designed to withstand heavy foot traffic.

To aid visibility and navigation, public stairs should have clearly defined edges. Use contrasting nosing colours, tactile indicators for the visually impaired, and avoid visual distractions that could cause missteps.

For specific requirements for different codes, see the table below for public staircase. 

PUBLIC STAIRCASE REGULATIONS BY CODE

 5.       STAIRCASE LIGHTING

Staircase lighting should balance safety and usability, with different considerations for public and private settings.

In both private and public stairs, overhead lights should be evenly spaced. Diffusers can be fitted to reduce harshness and glare.

In public stairs, clear nose visibility is critical for safety; using reflective materials or high-contrast colours, as well as dedicated lighting improves edge definition. Riser lighting can be achieved with LED strips, placed under stair noses, or with wall-mounted fixtures placed 100–300 mm (4–12 in) above treads. Light should always illuminate the full tread and shadows should be avoided.  

In public buildings, motion sensors can be fitted for energy conservation and emergency lights need to meet local regulations for emergency routes.

In private staircases, accent lighting can be used for a more subtle effect, such as LED strips under handrails to provide discreet, continuous lighting. Two-way switches offer convenient control from both ends of the stairs.

6.    COMMON MISTAKES IN STAIRCASE DESIGN

Common mistakes in staircase design can usually be easily avoided.

Research shows that a difference as small as 6mm (1/4 in.) between steps can significantly increase the risk of tripping. Humans are surprisingly sensitive to even tiny inconsistencies, and our bodies quickly adapt to a rhythm when climbing stairs, so even a slight deviation could cause a stumble. For internal staircases, following the “step formula” equation (2R + T = 600–630 mm) is the best way to ensure the tread and riser ratio is comfortable and safe.

Landscaping steps that are long and flat, are often miscalculated, resulting in an uncomfortable walking rhythm. The equation above does not work in this situation because our stride length on a flat ground is 600-700mm (1ft.11in.-2ft.3in.). An adjusted equation can be used to better suit flatter terrain: 2R + T = 630–700 mm.

Providing a minimum head clearance height of 2.1m (6ft.10in) is good practice anywhere in a building to avoid injury. With dangerous elements like steel stringers, head bumps can be particularly dangerous when combined with the risk of falling.

Horizontal rails on balustrades may look aesthetic, but they are also incredibly tempting to climb. Avoid these kinds of balustrades in schools or places where there are likely to be children around.

7.       CONCLUSION

As is often the case, good design goes unnoticed and bad design sticks out and hits you in the face. This is especially true in staircases where well-designed elements feel natural and secure, and poorly designed elements pose a significant safety risk. Understanding the general parameters, and being aware of common mistakes, will help to design better, safer staircases. The diagrams and tables here provide general guidelines to help you design fluidly and within industry standards, but please also always consult your local building codes.