Inspecting Spiral Staircases
Many staircases are poorly built. In addition to tripping hazards, many times they are not built to code. We know the requirements for “traditional” staircases. When inspecting a spiral staircase recently, my client and I both tripped when descending. My client asked me if the spiral staircase was built “up to code” I had to get my tape measure out. The requirements for rectangular treads differ from winder treads which also are different from a spiral staircase. All staircases with more than two treads should have a railing. A light and switch should be at the top and bottom of every staircase. The difference in height between any two risers should not exceed 3/8”. Riser boards should be used and open risers should not allow a 4” diameter sphere to pass. The minimum stairway width is 36” measured from the handrail. Minimum stairway headroom is 80”. So what are the requirements for a properly built spiral staircase?
Spiral Stairway Requirements:
- All treads should be identical
- The minimum tread depth is 7 ½” measured 12 inches from the narrowest side
- The maximum riser height is 9 ½”
- The minimum staircase width is 26”
- A stairway should not be more than 12 feet in height without a landing
- A landing should be as wide as the widest part of the staircase. If a door is present, the landing should be at least 36” X 36 “
- The spiral staircase should be properly attached with minimal movement
- It is recommended that another rectangular 36” staircase is present in addition to a spiral staircase
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