Codes

Local and state building authorities define the standards by which staircases and railings are constructed in their jurisdictions. Unless contractors meet these requirements, their constructions will not receive inspection clearance for use. Nearly all codes in the U.S. are based on the International Residential Code; the IRC is maintained by the International Code Council. Founded in 1994, this nonprofit organization streamlined the three existing codes at the time and eliminated conflict and duplication. The council also manages other regulations that affect staircase construction, including the International Fire Code and the International Building Code.

Basics

The IRC mandates at least one handrail on one side of a continuous flight of stairs with four or more steps. The rail must be about 34 to 38 inches high, measuring from the top of the rail grip to either the sloped plane next to the treads or an adjacent ramp slope. These height requirements needn't be complied with on rails that provide a transition between flights, or from stairs to a landing. This code can also be ignored on a rail over the lowest tread, which can use a volute, turnout or starting easing.

Sides

Stairways must maintain a minimum width of 36 inches from the handrail height up to the required headroom height of 80 inches. A handrail can project up to 4.5 inches on either side of the stairway, as long as it does not reduce the minimum clear width of the stair below the handrail. This width runs 31.5 inches for one handrail and 27 inches for handrails on both sides. Handrails must continue unbroken for the full length of the flight, starting from above the top riser to above the lowest riser. However, they can have a newel post at the turn. Handrails must be at least 1.5 inches from the wall or adjacent surfaces.

Bulkhead Enclosure Stairways

Bulkhead enclosure stairways are stairs that connect an outside grade level, such as a lawn, to an interior finished level, such as a basement. If these stairways meet the following conditions, handrail spacing can be ignored: The maximum height from the finished lower level to the outside grade must be 8 feet or less. The stairway must not be the only required exit from the basement. And the opening from the outside grade level to the stairway must be covered with hinged doors or other approved means.