Building Code for Stairs
Each of our stair lines, from custom indoor stairs lines to prefab outdoor stairs lines, 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 stair 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 of building code for stairs in your area before placing your order.
If you have any questions on what stair code-compliance means for your desired stair line, or want to learn more about spiral stairs, please feel free to contact us and we’ll help develop your spiral staircase plans.
Download stair building code specifications for prefab outdoor stairs and more Salter Spiral Stair products
Stair Building Code Requirement Highlights
- Minimum clear walking path of 26 inches. A 5-foot diameter or larger stair will provide this standard stair width
- Stair tread codes states that 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 staircase width. 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 Stair 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 according to stair codes
- Stair railing height code, 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 stair 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
R3126.96.36.199 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).