Stairs, Landings, Handrails, Guardrails
(Single-Family Residential)

Stairways must be constructed according to the requirements of the California Building Code (1998 CBC Chapter 10) to insure a safe means of access and egress.

Stairs: A run of steps with two or more risers is a stairway.

Alternate stairway types: Spiral stairs and winding stairs are rarely used and therefore not discussed herein. Refer to the building code for information on these types of stairs.

Materials: Exterior stairways, when constructed of wood, shall be built with 2" nominal lumber. When exposed to the elements, they shall be constructed of pressure treated wood or wood with a natural resistance to decay (i.e., redwood free of sapwood).

Width: Stairways serving a single-family dwelling shall be a minimum of 36" wide. Stringers, decorative trim, etc., may project a maximum of 1-1/2" into the required width from either side.

Rise and Run: For residential stairs, the maximum riser shall be 8" and the minimum run shall be 9".

The rise and run shall be uniform with a maximum tolerance, from the largest to the smallest riser or tread, of 3/8".

When the top or bottom riser meets a sloping grade, the design riser height shall be maintained at the centerline of the stairway width.

Headroom: All stairways shall have minimum headroom of 6-feet 8-inches measured vertically from the line of the tread nosings to any soffit or projection above.

Loads: Treads shall be capable of supporting a 300 lbs. concentrated load applied at any point. The stringers shall be capable of supporting a 40-lb./sq. ft. uniform load.

Drainage: Each stairway shall have a landing at the top and bottom of the run of stairs. The landing dimension in the direction of travel shall not be less than 36". For stairways with a straight run, having a total rise exceeding 12 feet, an intermediate landing shall be provided. Landings shall be at least as wide as the stairs.

Handrails

A handrail shall:
· Have a gripable surface not less than 1-1/4" and not more than 2" in cross-sectional dimension or shall provide an equivalent gripping surface. Note: Traditional handrail profiles that do not conform to the 1-1/4"-2" dimensions may be acceptable; check with the Building Division regarding the particular installation.
· When projecting from a wall, a minimum 1-1/2" space between the wall and the rail is required.
· Be installed and not less than 34" nor more than 38" from the top of the rail to the line of the nosings of the stairs.
· Have returned ends or rounded terminations or bends.
· Be continuous the full length of each flight of stairs and shall extend, as a minimum, from the bottom riser to the top riser.
· Be so constructed that it is capable of supporting a 200 lb. load applied at any point along the rail in any direction
· Be required on one side only for stairways serving individual dwelling units.
· Not be required for stairways having less than four risers when serving individual dwelling units.

Guardrails: Guardrails are required along open sides of stairways, landings, balconies, porches, decks, floor openings, ramps, and roofs used for other than service of the building, which are more than 30" above grade.

Detailed guardrail requirements:

· Guardrails are required at the sides of stairways, landings, ramps, porches, and balconies that are more than 30" above grade or the floor below.
· Guardrails shall have a 36" minimum height, 34" high along open sides of stairways.
· Guardrails must be able to withstand a load of 20 pounds per lineal foot applied horizontally at the top of the guardrail.
· Intermediate rails, panels or fillers, and their connections, shall be capable of withstanding a load of 25 pounds per square foot applied at right angles to the guardrail.
· Guardrails shall be designed so that a 4" diameter sphere cannot pass through the triangular space formed by the bottom of the rail, the riser and the tread.

If you additional information, please call the Building Division at (650) 991-8061.

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