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Construction Tip Sheet 01 March 15, 2024 MyBuildingPermit.com I Basic Stairs 1 Basic Stairs This tip sheet reflects code requirements of the 2021 International Residential Code (IRC) with Washington State Amendments. Figure 1: Typical Stair Treads and Risers Stair Treads and Risers □ The largest tread or riser within any flight of stairs is not to exceed the smallest by more than 3/8 inches. (R311.7.5.1) Illumination □ Interior stairways shall be provided with an artificial light source to illuminate the landings and treads. There shall be a wall switch at each floor level to control the light source where the stairway has 6 or more risers. (R303.7) □ Exterior stairways shall be provided with an artificial light source located at the top landing of the stairway and located at the bottom landing where accessing a basement. Stairway illumination shall receive primary power from the building wiring. (R303.8) Handrails □ Handrails are required on at least one side for stairways with four or more risers. See Tip Sheet 2 for additional information regarding handrails. (R311.7.8) 2018 ---PAGE BREAK--- Construction Tip Sheet 01 March 15, 2024 MyBuildingPermit.com I Basic Stairs 2 Landings □ Landings are required at the top and the bottom of stairways. A floor landing is not required at the top of an interior flight of stairs, including stairs in an enclosed garage, provided a door does not swing over the stairs. (R311.7.6) □ A landing extending the width of the stairs and measuring a minimum of 36 inches in the direction of travel is required at the top and bottom of every stairway. (R311.7.6) Circular, Winding, or Spiral Stairways □ For exceptions related to the construction of circular, winding, or spiral stairways, see IRC R311.7.5.2.1 and R311.7.10. Figure 2: Typical Stair Elevation ---PAGE BREAK--- Construction Tip Sheet 01 March 15, 2024 MyBuildingPermit.com I Basic Stairs 3 Figure 3: Headroom Clearance Requirements