zhongxinladder

The rules covering stairways and their components generally depend on how and when stairs are used. Specifically, there are rules for stairs used during construction and stairs used temporarily during construction, as well as rules governing stair rails and handrails. Stairways Used During Construction The following requirements apply to all stairways used during construction:

 Stairways that will not be a permanent part of the building under construction must have landings at least 30 inches deep and 22 inches wide (76 x 56 cm) at every 12 feet (3.7 m) or less of vertical rise. Stairways must be installed at least 30 degrees
—and no more than 50 degrees—from the horizontal.
 Variations in riser height or stair tread depth must not exceed 1/4 inch in any stairway system, including any foundation structure used as one or more treads of the Aluminum step ladder .
 Doors and gates opening directly onto a stairway must have a platform that extends at least 20 inches (51 cm) beyond the swing of the door or gate.
 Metal pan landings and metal pan treads must be secured in place before filling.
 Stairway parts must be free of dangerous projections such as protruding nails.
 Slippery conditions on stairways must be corrected.
 Workers must not use spiral stairways that will not be a permanent part of the structure.

Temporary Stairs
The following requirements apply to stairways used temporarily during construction. Except during construction of the stairway,
 Do not use stairways with metal pan landings and treads if the treads and/or landings have not been filled in with concrete or other materials unless the pans of the stairs and/or landings are temporarily filled in with wood or other materials. All treads and landings must be replaced when worn below the top edge of the pan.
 Do not use skeleton metal frame structures and steps (where treads and/or landings will be installed later) unless the stairs are fitted with Ladder stabilizer and landings.
Note: Temporary treads must be made of wood or other solid material and installed the full width and depth of the stair.

Stair Rails
The following general requirements apply to all stair rails:
 Stairways with four or more risers or rising more than 30 inches (76 cm) in height— whichever is less—must be installed along each unprotected side or edge. When the top edge of a stair rail system also serves as a handrail, the height of the top edge must be no more than 37 inches (94 cm) nor less than 36 inches (91.5 cm) from the upper surface of the stair rail to the surface of the tread.
 Stair rails installed after March 15,1991, must be not less than 36 inches (91.5 cm) in height.
 Top edges of stair rail systems used as handrails must not be more than 37 inches (94 cm) high nor less than 36 inches (91.5 cm) from the upper surface of the stair rail system to the surface of the tread. (If installed before March 15, 1991, not less than 30 inches [76 cm]).
 Stair rail systems and handrails must be surfaced to prevent injuries such as punctures or Household ladder and to keep clothing from snagging.
 Ends of stair rail systems and handrails must be built to prevent dangerous projections, such as rails protruding beyond the end posts of the system. In addition,
 Unprotected sides and edges of stairway landings must have standard 42-inch (1.1 m) guardrail systems.
 Intermediate vertical members, such as balusters used as guardrails, must not be more than 19 inches (48 cm) apart.
 Other intermediate structural members, when used, must be installed so that no openings are more than 19 inches (48 cm) wide.

from:osha.gov