Building Code

Each of our stair lines for indoor and outdoor applications is available in code-compliant options.

Our spiral stair building code specifications provide technical details about the different code and non-code packages we offer for commercial and residential projects. These specifications show dimensions for height, tread degree, rotation degree, and many more details for each Salter Spiral Stair product type. Please check with your local building inspector for the dimensional requirements in your area before placing your order.

If you have any questions on what code-compliance means for your desired stair line, please feel free to contact us.

Download building code specifications for Salter Spiral Stair products

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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

IRC Stair Building Code

R311.1.10.1 Spiral stairways. Spiral stairways are permitted, provided the minimum clear width at and below the handrail shall be 26 inches (660 mm) with each tread having a 71/2-inch(190 mm) minimum tread depth at 12 inches (914 mm) from the narrower edge. All treads shall be identical. and the rise shall be no more than 91/2inches (241mm). A minimum headroom of 6 feet 6 inches (1982mm) shall be provided (See diagram).

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