What Are the California Building Codes for Stairways?

• Stairway construction requires strict adherence to detail in California.stairway image by jeancliclac from Fotolia.com
  
  The California Department of Industrial Relations maintains an online directory of the Code of Regulations governing the construction and specifications for all stairways in the state. Part (a) of subchapter seven states that every stairway in or on any building must follow all requirements set forth in the rest of the code. The code is current as of June 2010.
  
  

Stairway Width

• Public and private stairways in a building with an occupant load of above 50 people must be 44 inches wide or wider. Stairways that will serve a load of 50 people or fewer must be at least 36 inches wide, and private stairways with a load of fewer than 10 people must be at least 30 inches wide.
  
  You are allowed to include handrails and trim that extend out three and a half inches from each side of the stairway as part of the width requirements. Stringers can project out 1 and 1/2 inches or less.
  
  

Rise, Run and Step Surfaces

• The code requires the rise, or vertical height, of stairs to fall between 4 and 7 and 1/2 inches. The run, or horizontal depth, of stairs to be 10 inches or greater. The law further specifies that the variance in tread run and rise height between the largest and smallest stairs must be no greater than 3/8 inch. Private stairways with occupant loads of fewer than 10 may have up to an 8-inch rise and a minimum of a 9-inch run.
  
  The code also stipulates that stairways must be well maintained and kept clear at all times and that all stairway treads must be slip-resistant.
  
  

Circular Stairways

• The code allows for circular stairways as building exits as long as the minimum run width is 10 inches or more. All treads in any given flight of circular stairs must have identical dimensions to one another within a 3/8-inch tolerance.
  
  

Landings

• The code states that landings must be equal in width to the width of the stairway. Landings are to be measured in the direction of travel of the stairway according to the code. On stairways with straight runs, the landing never needs to be more than 4 feet. Doors in landings must not reduce the required width by less than half at any part of the swing of the door. When completely open, the door must not reduce the width by more than 7 inches.
  
  

Roof Stairways

• Every building 4 stories high or higher must have a stairway to the roof except in cases of roofs with slopes more than 4 in 12, which means the roof rises more than 4 inches for every 12 inches of horizontal run.
  
  

Headroom Clearance

• Every stairway must have a headroom clearance of at least 6 feet and 6 inches measured vertically from the stairway tread to the ceiling. Stairways that predate the current code with overhead clearances of less than 6 feet 6 inches must be made to conform to the requirements. If it is impossible to increase the clearance, a warning must be posted at the stairway indicating the lower clearance. The code requires padding to be installed in cases where it will enhance the safety of the stairway.