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US Spiral Stair Building Code
Building Code Requirement Highlights
- Minimum clear walking path of 26 inches. A 5-foot diameter or larger stair will provide this width
- Each tread will have a minimum of 7 1/2 inch tread depth at 12 inches from the narrow edge
- All treads will be identical
- The tread rise shall not be more than 9 1/2 inches high
- Minimum headroom of 6 foot 6 inches shall be provided, measuring plumb from the edge of the platform down to the tread below
- Landing width shall not be less than the required width of the stairway. Minimum spiral stair tread width is 26 inches – Salter’s code platforms start at 31 inches wide
- Stair balusters shall be spaced so a 4-inch object cannot pass between. The IRC Code permits a 4 3/8 inch space
- Balcony/Well Enclosure guardrail balusters shall be spaced so a 4-inch object cannot pass
- Balcony/Well Enclosure guardrail height shall not be less than 36 inches – If your state or municipality requires 42-inch tall guardrails, the sales order must reflect this detail
- The stairway shall be equipped with one handrail on the wide edge of the tread
- Handrail height, measured vertically from the tread nosing, shall be not less than 34 inches and not more than 38 inches
- Handrail grip size
- Type I-Handrails with a circular cross section shall have an outside diameter of at least 1 1/4 inches and not greater than 2 inches – Salter’s standard circular handrail is 1 1/2 inch diameter. This will address the UBC minimum cross section of 1 1/2 inch diameter. If the handrail is not circular, it shall have a perimeter dimension not greater than 6 1/4 inches
- Type II-Handrails, with a perimeter greater than 6 1/4 inches, shall provide a graspable finger recess area on both sides of the profile. For further information on our Type II options, please contact our sales department
- Verify what handrail size and shape your inspector will require. Handrail size and shape are a very controversial area within the building code. We recommend that you use our standard 1 1/2″ round handrails or our 1 3/4″ x 1 3/4″ solid wood handrail to comply with the proper circumference
- A 300 lb. concentrated load is required. On request, our sales department can provide structural calculations for your job specifications