Spiral Stairway Minimum Headroom Clearance
The minimum spiral
stairway headroom clearance is 6 feet and 6 inches.
However, the Minimum Headroom Stair Clearance for almost every other stairway is going to be 6 feet and 8 inches. Don't get these two measurements confused.
The headroom clearance is going to be measured from the tip of the stair nosing on the stair tread to the closest vertical distance, directly above.
Special Tip: If you're designing a set of spiral stairs, make sure that you allow for a minimum of 6'6" in headroom, otherwise you could find yourself working on the demolition crew, as the building inspector makes you tare the stairway part and rebuild it correctly.