Do Those Stair Meet Code? Well... It Depends
Do Those Stairs Meet Code? Well... It Depends
It happens, someone has fallen down the stairs. One of the first questions should be, “do those stairs meet code?” EDT engineers are often asked to inspect a set of stairs and determine if they comply with the applicable building codes. The actual onsite inspection is fairly straightforward, primarily requiring one tool – a tape measure. How high are the risers? How long and wide are the treads? How high is the handrail? This, that, and a few other things.
The code evaluation gets to be trickier and revolves around which edition of the local building code is applicable. Typically, a new edition of the model building code is published every three years and various states and local municipalities make changes or “modifications” to the national codes. The applicable code is based on the location of the building and the date of the construction.
In 2000, the International Building Code and International Residential Code became the model code accepted nationwide. Before that, different regions of the country preferred different codes. The Standard Building Code was used across most of the southeast. The Standard Building Code had evolved from the Southern Building Code. The City of Charleston (South Carolina) Building Department has a historical listing of adopted building codes dating back to 1895. The early codes were developed by insurance companies and mostly addressed fire safety. Most jurisdictions do not go back that far, but they often have a list of Historic Code Adoptions.
Why does the particular edition of the building code matter?
Because some of the stair requirements can change with each new code edition. It might just be a 1/4" variation, but that can be the difference between your stairs satisfying the requirement of the code or not. This is a pass/fail test.
Will you know the exact code edition that applies?
If you get real lucky, have great karma, and have never kicked a dog – maybe. The rest of us – probably not. But we can get close. Let’s say our house in question was built in 1987. The likely code editions for this house would be the 1985 CABO (Council of American Building Officials), One and Two Family Dwelling Code or the 1985 Standard Building Code. If you have access to those codes, that is great. If not, you bracket in with what you have available. In this case, the 1983 and 1989 CABO, and 1988 SBC were obtainable.
Our example 1987 stairs had the following conditions:
- Overall Width; 34" at the top and 36" at the bottom
- Head Height: 6'-9"
- Tread Depth: 8-3/4" to 9-1/2"
- Riser Height: 7-1/8" to 7-3/4"
- Handrail Height: 33-37"
- Tread Variance: 3/4"
- Riser Variance: 5/8"
Tabulating the actual conditions with the various code requirements will show any violation trends. The following chart is color-coded with red meaning there is a violation. An entry with (3/9) would indicate that 3 of the 9 treads did not meet that code provision.
In our example, we do not know the exact building code that is applicable and likely would not have access to that particular code even if we did. We do know that those stairs do not fully satisfy building codes issued both before and after the suspected time of construction. So It would be reasonable to expect these stairs did not satisfy the applicable building code at the time of construction. A measurement that is often out of compliance is the maximum variation of tread or riser dimensions of 3/8". This requirement has remained 3/8" for decades. An exception can be made for the bottom step onto a public walkway.
There are many other criteria – the diameter of the handrail, the distance of the handrail from the wall, the extension length and condition of the handrail ends, the radius of the tread nosing, slope of the treads… If you cannot pass the simple tread and riser dimension questions, do the others really matter? This was, after all, a pass/fail test.
About the Author
David Horne, P.E. is a Consulting Engineer in our Charleston, SC Office. Mr. Horne provides consultation related to construction evaluation of residential and commercial structures, failure analysis, evaluation of scope and cause of damage to structures, repair cost analysis, wind and hail damage assessment, and water intrusion investigations. You may contact him for your forensic engineering needs at firstname.lastname@example.org or (843) 832-1052.