Spiral Staircase Calculator
Spiral Staircase Design
Calculate dimensions and materials for a spiral staircase
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Formula
Steps = ceil(FloorHeight / RiserHeight); Rotation = Steps x 30°; Headroom = (360/30) x ActualRiser
Frequently Asked Questions
What is the minimum diameter for a spiral staircase?
Building codes typically require a minimum diameter of 60 inches (5 feet) for a spiral staircase. However, 66-72 inches is more comfortable. The minimum clear width should be 26 inches.
How do you calculate headroom for spiral stairs?
Headroom is the vertical distance gained in one full 360-degree revolution. It must be at least 78 inches (6.5 feet) per most building codes. Calculate it as (360 / degrees_per_step) x riser_height.
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