BUILDING CODES FOR STAIRS
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Building Code for Stairs
Whether you are building new stairs or renovating old stairways, it is important to understand applicable stair codes. Codes vary by type of stair (residential stair codes versus commercial stair codes and interior versus exterior). In this article, building codes for stairs will be broken down to give a general understanding of stair code requirements. Remember to check your local building codes for stair specifications to ensure proper compliance.
Defining Stair Parts
What is a stair tread and stair riser? The tread and riser are referred to in all building codes. The stair tread is the horizontal portion of the staircase on which people walk, the stair riser is the vertical portion of the staircase between each tread. Stair treads and stair risers can be made of a variety of materials with treads often having a partial or total surface with some non-slip properties for safe egress.
Another important question is: what is stair nosing? Stair nosing can refer to two things. First it refers to the front portion of a stair tread, this can extend over the riser, meet at a 90 degree angle with the riser, or be angled back at a slight return.
The second definition of stair nosing is a piece of non-slip and/or color contrasting material embedded in or secured onto the front of a stair tread. Usually these stair nosings are from just under 2 inches to as much as 5 inches deep. They can contain material that will help prevent slips, provide a visual aid in seeing the next tread and even glow in the dark properties to help in power outages and emergency evacuations. If people need to exit the building these safety features can allow them to egress quickly via an exterior exit.
Stair Building Code and Tread Requirements & Compliance with Building Standards
Stair code requirements vary slightly between commercial and residential buildings. When beginning construction on a new building or doing renovations on an existing structure, it is important to be familiar with the different regulations and inspector practice. This includes ensuring that the correct dimensions are being used, based on the type of building or home. This applies to both an interior or exterior stair. The International Code Council (ICC) supervises many various codes, including two which are specific to stairs.
International Residential Code (IRC)
The International Residential Code dictates stair code requirements specific to residential buildings. The IRC stairs code states that, to comply with stairway requirements, the minimum width for residential stairs be no less than 36 inches. The stair riser code is up to 7.75 inches, and can not vary more than 3/8 of an inch. There are also section codes in place for standard stair tread dimensions. The tread depth code for residential stairs should be no less than 10 inches with nosing, no less than 11 inches without nosing, and maximum tread depth variation should also be less than 3/8 of an inch.
International Building Code (IBC)
Alternately, there are commercial stair code regulations to comply with as well. There are small variations in stair tread dimension for residential vs. commercial buildings. The International Building Code sets the commercial building code for stairs. The IBC stair codes are slightly different than the ones set by the IRC. For example, the maximum stair riser height is 7 inches, and minimum is 4 inches. The stair tread code requirements are also slightly different, with a minimum depth of 11 inches. For both of those codes, the maximum tolerated difference in height and depth is 3/8 of an inch, the same as for residential stair code measurements. Another stair specification section by the IBC commercial stair codes is that stair tread nosing is not required as long as the minimum depth is 11 inches.
Americans with Disabilities Act (ADA) Compliance
Another thing to consider when building or altering a set of stairs is the Americans with Disabilities Act. The ADA protects individuals with disabilities in many aspects of their lives, including ensuring that all buildings are safe and compliant with acceptable standards. The ADA states that all stairs and stairway must have uniform riser heights and tread widths. One section also states that stair treads cannot project past the stair riser by more than 1/2″ and should be curved or beveled to help prevent falls from a step.
Importance of Safe Stairways
The building code for steps are in place for the safety of everyone that may use those stairs. It is important to remember that uniformity is perhaps the most important thing to take away from this and that your inspector will be watching for you to comply. If all step & stair measurements are the same for tread depth and riser height, any safety risk will be greatly reduced. Stairway code requirements are in place for a reason, and with stairs that fall into the mandatory dimensions specified by the IRC and IBC, the worry for any hazard should be eliminated.