Are Stairs Considered Structural Elements in Building Design?

Stairs play a crucial role in building construction, not just as a means of vertical transportation but also as structural components. They are designed to carry specified loads similar to slabs and platforms intended to support human traffic. Understanding the structural aspects of stairs is essential for ensuring safety and compliance with building codes.

Stairs as Structural Elements

Any platform, whether flat or slightly slanted, that is intended to support humans temporarily or permanently, whether they are maintenance workers or office employees, should be designed as a structure. Stairs can indeed be and often are used as part of the crossbracing in a building, making them an essential structural part of the architecture.

Building Codes and Stair Loads

Stairs must be strong enough to support both dead and live loads. Dead loads refer to the weight of the stairs themselves, while live loads include the weight of people and any other imposed loads. For instance, if moving heavy items such as washers or fridges, stairs must be strong enough to handle these additional loads.

Code Requirements for Stairs

Stairs serving single or two-family dwellings must support 40 pounds per square foot over the entire stair and a point load of 300 pounds anywhere on the stair. Stairs for other buildings must support 100 pounds per square foot over the entire stair and a point load of 300 pounds anywhere on the stair. The stringers supporting the stairs, the treads, and the rest of the structure must be designed to meet these load requirements.

OSHA Standards and Industrial Facilities

The Occupational Safety and Health Administration (OSHA) provides specific requirements for stairs in industrial facilities. These requirements can sometimes exceed those of the Uniform Building Code. For example, industrial facilities often have stricter requirements to ensure the safety of workers who handle heavy machinery or hazardous materials.

Designing for Higher Loads

Building codes are designed to anticipate common use, but sometimes, the intended use may result in higher loads than what the codes require. In such cases, the stairs must be designed to support the expected loads. This proactive approach ensures that the structure can handle the intended use without structural failure.

Construction Materials and Stability

Often, the stair shaft is made of poured concrete or concrete block, which helps to withstand horizontal forces such as wind or earthquakes. This design ensures stability and resilience, contributing to the overall structural integrity of the building.

Liability and Maintenance

Should a stair collapse and cause an accident, there can be significant liability issues. Legal and safety considerations require that stairs be maintained to ensure structural integrity. Regular inspection and maintenance can prevent accidents and ensure that stairs continue to support their intended loads safely.