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Stairs

Stairs are a series of steps that connect one floor level to another. Each step has a horizontal tread to stand on and a vertical riser between treads, and a full run of steps with its landings is called a staircase or stairway.

Common layouts include straight runs, L-shaped stairs with a landing, U-shaped stairs that turn back on themselves, and spiral stairs. In the United States, the International Residential Code limits riser height to 7 3/4 inches and requires treads at least 10 inches deep, along with minimum headroom and handrail rules.

On a plan, stairs appear as a row of parallel lines with an arrow showing the direction of travel. For square footage, ANSI Z765 includes a staircase in the floor from which it descends, so the stair opening on that floor is not deducted. See do stairs count as square footage.