Commercial Stair Codes

IBC code Requirements for Stairs

(last updated to IBC 2021)

• The difference between a Stairway, an Egress Stairway1011, an Accessible Egress Stairway1009.3, an Exit Access Stairway 1019, an Interior Exit Stairway 1023 and an ExteriorExit Stairway 1027?

  • Section 1011.1 General says that all stairways weather an egress stairway or not must comply with the requirements of the sections outlined. There are rules throughout that only apply to egress stairways however that will not apply to non egress stairways such as winder treads, etc.

1011 Stairways (Egress)

• 1011.2 Width and Capacity determining min width of a stairway and how to measure

  • Min width of any stair

  • Sections 1005.3.2 Other Egress components and 1005.6 Egress Convergence

  • 1009.3.2 Stairway Width min width of accessible egress stair

• 1011.3 Headroom min clearance req’d and how to measure

• 1011.4 Walkline defines walkline for determining winder tread design (curved stairs)

• 1011.5 Stair Treads and Risers Rules for design

  • 1011.5.2 Riser Height and Tread Depth

    • max & min riser heights allowed and how to measure.

      • Never design stairs to max or min riser height allowed to allow for construction tolerances as this is the max allowed after it is constructed.

    • min tread depth allowed and how to measure it.

      • Tread depths can be built exactly so designing them to the code min is fine.

  • 1011.5.3 Winder Treads are not allowed in means of egress stairways except within a dwelling unit.

  • 1011.5.4 Dimensional Uniformity

    • 1011.5.4.1 Nonuniform Height Risers allows for some tolerance at the top and bottom riser of exterior stair conditions.

  • 1011.5.5 Nosing and Riser Profile rules for nosings if provided, and open riser stairs.

    • Specific locations where non-solid risers are allowed. otherwise solid risers are required everywhere.

• 1011.6 Stairway Landings locations and sizing of req’d landings

• 1011.7 Stairway Construction

  • 1011.7.1 Stairway Walking Surface flatness and opening requirements.

  • 1011.7.2 Outdoor Conditions drainage of walking surfaces

  • 1011.7.3 Enclosures Under Interior Stairways Fire protection requirements

  • 1011.7.4 Enclosures Under Exterior Stairways Fire protection and use restrictions

• 1011.8 Vertical Rise max vert rise on a flight of stairs before a landing or level

• 1011.9 Curved Stairways requirements

  • Difference between a curved stair and a spiral stair

• 1011.10 Spiral Stairways where allowed and design req’s

• 1011.11 Handrails are to be provided on both sides and other req’s and exceptions

• 1011.12 Stairway to Roof where req’d and penthouse requirement

• 1011.13 Guards where req’d

• 1011.14-16 Alternating Tread Devices, Ship’s Ladders, and Ladders

Accessible Egress Stair 1009.3

• Additional requirements and the exceptions

  • Exit Access Stairways are not allowed to be counted as Accessible Egress stairs

  • Additional stairway width requirements with exceptions

  • Area of Refuge requirements with exceptions