City of Hopkins • Stairs & Guardrails

This page provides basic information for residential stairs, handrails, and guardrails. Because circular and spiral stairs are rarely used in residential construction, those types of stairs are not covered in this handout. If you are contemplating the use of one of those stair designs, please contact the Inspections Division.

The information in this handout is based on Sections 314, 315, and 316 of the International Residential Code.

The following spatial requirements apply to stairs:

Minimum width above the handrail height is 36 inches.
Handrails may project not more than 4 ½ inches from the side of the stair.
The minimum clear width from the handrail height to the treads is 31 ½ inches for stairs with rails on one side and 27 inches for stairs with rails on both sides.
A minimum of 6 feet, 8 inches of headroom is required measured vertically from the nosing of the treads. 6 feet, 8 inches of headroom is required at all landings.
The maximum riser height in any stair may not exceed 8 inches measured from the top of one tread to the top of any adjacent tread.
The minimum tread depth shall be 9 inches measured from the nosing of one tread to the nosing of any adjacent tread.
The greatest tread or riser dimension shall not exceed the smallest tread or riser dimension by more than 3/8 inch.
Open risers are not permitted when the total rise of the stair exceeds 30 inches unless the open space is such that a 4-inch diameter sphere will not pass through.
For winder stairs, the width of the tread must be at least 9 inches at a point 12 inches from the side where the treads are narrowest. The minimum width of any tread may not be less than 6 inches. A continuous handrail is required on the side of the stair where the treads are narrowest.
When the underside of stairs is enclosed with walls and a door, the walls, ceilings, and under side of the stair must be covered with ½ inch gypsum board.

Stairs must be designed for a 40 pound per square foot uniformly distributed live load. Treads must be designed for the uniformly distributed live load or a 300-pound concentrated load acting over an area of 4 square inches, whichever produces the greatest stresses.

How to measure stair headroom

Note: The maximum tread depth cannot exceed the minimum tread depth by more than 3/8 inch and the maximum riser height cannot exceed the minimum riser height by more than 3/8 inch.

Handrails are required on at least one side of all stairs with four (4) or more risers.
Handrails must be mounted between 34 and 38 inches above the nosing of the stair treads.
Handrails must extend from a point directly above the bottom riser to a point directly above the top riser.
Handrails must be continuous for the entire length of a flight of stairs.
The ends of handrails must be returned to the wall or terminate in a newel post.
Handrails adjacent to a wall must have a space of not less than 1 ½ inches between the handrail and the wall.
Handrails must be designed to support a 200 lb load applied in any direction at any point along the top of the rail.
Handrails must meet the following grip size requirements:
1. The handrail must have a circular cross section of 1¼ inches to 25/8 inches.
2. Other handrail shapes that provide an equivalent grasping surface are permissible.
3. Edges of handrails shall have a minimum radius of 1/8 inch.
4. The use of a 2X4 or other dimension lumber placed either on edge or flat is not an acceptable handrail.

Acceptable handrail details

Note: Other shapes may be acceptable if they provide an equivalent gripping surface.

Guards are required for any porch, balcony, deck, or other raised floor surface that is located more than 30 inches above the floor or grade below. Guards at these locations must be not less than 36 inches in height.
Guards are required on the open side(s) of stairs with a total rise of more than 30 inches above the floor or grade below. Guards on stairs must be not less than 34 inches high measured from the nosing of the treads.
All required guards must have intermediate rails or a decorative pattern such that a 4-inch diameter sphere will not pass though except that the triangular space formed by the bottom or a guard, a stair riser and stair tread may be such that a 6-inch diameter sphere will not pass through.
Guards must be designed to support a 200 lb load applied in any direction at any point along the top of the guard.

Guardrails

Summary of stair, handrail, and guardrail requirements

Minimum width - 36"
Maximum rise - 8". Minimum rise - 4".
Minimum run - 9".
Handrail must be between 34" and 38" above nosing of treads.
Minimum headroom clearance - 6'8", measured vertically from the plane of tread nosings to soffit above.
Guardrail height - 36".
Intermediate rails placed so that a sphere 4" in diameter cannot pass through.
Guardrail required if deck, porch, balcony, landing, etc. more than 30" above grade.

Note: Enclosed usable space under stairs must be protected on the enclosed side by ½ inch gypsum wallboard.

For more information, contact at 952-548-6320.