Overview of Standard Stair Rules & Regulations
How do you build a staircase that meets building codes? A staircase built here in Florida needs to meet different regulations than one built in Washington or New York. However, these local codes mostly follow regulations laid out by OSHA and IBC. Standards from these organizations are a great starting point for designing your stairs, no matter where you’re building them.
How Do Building Codes Improve Stairs?
Codes aim to make stairs that are easy and safe for people of all sizes to use. This boils down to five main elements of design.
Stairs must be even to be safe. When we go up or down stairs, our bodies get in a rhythm. If one step is taller, shorter, deeper or shallower than the others, we’ll misstep and stumble.
We need plenty of space for our feet to land. Some extra space can be added to risers with nosing. However, if the nosing extends too far, we can trip on it going up stairs.
The space above the stairway must have space for tall people, while the height of each step must be small enough for the strides of short people.
Handrails provide support for stability. They need to be positioned where they’re within easy reach of most people, without intruding too much into the stairwell.
Climbing and descending stairs is difficult for many people, especially if they’re carrying something. By breaking up a stairway into flights, they have a chance to rest at landings.
What Is the Code for Stairs in a House?
Local building codes are generally designed around the International Building Code for stairs and handrails and the International Residential Code for One and Two Family Dwellings. The IBC and IRC codes lay out the following requirements for stairs.
The minimum width of each stair is 36 inches. Handrails can project up to 4 ½ inches into this space. This leaves at least 31 ½ inches of space with one rail, and 27 inches with two rails.
Handrails are required on at least one side if there are more than four risers. The rail must have at least 1 ½ inches of clearance from the wall. Round handrails can be 1 ¼ to 2 inches in diameter, while square rails can have a cross section up to 2 ¼ inches. If you want to install another shape of handrail, the total perimeter must be under 6 ¼ inches. The rail must be mounted between 34 and 38 inches above the risers.
The difference in height between each riser can be a maximum of 7 ¾ inches. Variation between step heights can be no more than 3/8ths of an inch. These measurements should be taken from bare risers, since the height of runners and carpeting varies depending on the load put on them.
The depth of each stair must be at least 10 inches. If you want to install stairs without nosing, each stair must have a depth of at least 11 inches. Like stair height, depth between stairs can’t vary by more than 3/8ths of an inch. All nosing must be between ¾ and 1 ¼ inches in length.
Each flight of stairs can be no more than 12 feet 7 inches from the floor. For taller staircases, flights should be divided by landings.
Headroom — the distance between the top of each stair and the ceiling — must be at least 6 feet 8 inches.
What Is the OSHA Standard for Stairs?
No matter where you are, the commercial building code for stairs is based on requirements from OSHA. Stairs are covered by OSHA standard 1910.25, while handrails and guardrails fall under standard 1910.28. Stairs that meet IBC residential regulations also meet most of the requirements for OSHA. However, there are a few key differences due to how and where commercial stairs are used.
Stairs under 44 inches in width require at least one handrail. Stairs over 88 inches in width require handrails on both sides, as well as a center handrail. A handrail must be installed on open sides of the staircase, and these rails must meet guardrail requirements. They can have a mid-rail at half the height of the handrail, or a series of posts no more than 19 inches apart. These rails and posts keep people from falling off of the stairs if they trip.
Stair width, excluding handrails, must be at least 22 inches, while height clearance between the steps and the ceiling must be at least 6 feet 6 inches. Risers can have a maximum height of 9.5 inches, and treads must be at least 9.5 inches deep.
Standard staircases must have an angle between 30 and 50 degrees.
How Can I Build a Staircase That’s Comfortable To Use?
These codes leave some leeway, so you choose angle and height based on available space. However, if you're working with new construction, you have the option of optimizing your design for easy climbs and descents. A shallower angle makes stairs easier to climb, up to a point. Stairs of 30 degrees are the easiest to climb, while anything over 45 degrees is difficult to climb. The OSHA code makes exceptions for angle limits in areas with limited space, like ships. A riser height between 6 to 6 ½ inches is comfortable for most people.