International Building Code for Stairs

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The International Building Code (IBC) provides for step and stairway rules in chapter ten of the IBC code book. California’s building code is adopted from and closely mirrors the IBC. Here are some of the rules that are in the building code:

international building code for stairs

The depth of all the treads on a staircase must be the same from front to back, with a maximum variation of 0.375 inches between the deepest and shallowest treads. Treads shall be a minimum depth of 11 inches.


A step riser is the distance from the top of one step to the top of the next step, measured vertically. Risers must have a maximum variance of 0.375 inches between the highest and lowest risers on the staircase. Risers must have a maximum height of seven inches and a minimum height of four inches. Single-family homes and townhouses are permitted to have a maximum riser height of 7.75 inches.


Stairways of more than a single step within or attached to residential or commercial structures must have a handrail along either or both sides of the stairway.


Stairways must be a minimum of 36 inches wide and have a headroom minimum of 80 inches along the full course of the stairs and one tread length beyond the bottom step. Every stairway is required to have a landing with a length equal to the width of the stair, but landing lengths over 48 inches are not required. Stairs with a total vertical rise of more than 12 feet must have a landing between the top and bottom landings.


Spiral and circular steps and staircases have special codes that apply only to them, as specified by IBC sections 1009.7, 1009.8 and 1009.9. There are also alternating tread devices are also allowed in special circumstances, as provided for in section 1009.10.


Do you suspect that your stairs don’t follow the IBC rules on stairs and are worried about your safety? If you live in the Los Angeles area, call us at 310 994 4626 or e-mail us at We can do the staircase inspection for you and work on the necessary adjustments.