In North Carolina, deck stair stringers have to follow the same residential code the rest of your deck does: risers no taller than 7¾ inches, treads at least 10 inches deep, stringers cut from solid 2×12 lumber, and enough of them that a step stays firm when you put your weight on it.
Get those dimensions right and the stairs pass. Miss them and it is usually the stairs an inspector flags first.
Stairs take more abuse than any other part of a deck, so it helps to know what code is asking for before you build.
What a Stair Stringer Actually Does
A stringer is the sawtooth board running at an angle from the deck down to the ground. The treads (the parts you step on) and the risers (the vertical backs of each step) both fasten to it. Every set of deck stairs rides on at least two or three of these boards, and they carry the entire load of anyone walking up and down.
Because they hold so much, code treats them as structural framing. Cut the boards wrong and you have more than an ugly staircase, you have one that can fail.
The Stair Numbers NC Code Cares About
North Carolina follows the state residential code, which sets firm limits on stair dimensions. These are the required figures that matter most:
|
Requirement |
What code asks for |
|
Maximum riser height |
7¾ inches |
|
Minimum tread depth |
10 inches |
|
Variation between steps |
No more than 3/8 inch across the whole flight |
|
Minimum stair width |
36 inches |
|
Guard height on the deck |
36 inches minimum |
A tall staircase has one more limit: total rise. Once the total rise of a single flight climbs past about 12 feet, code requires an intermediate landing to break it up.
That 3/8-inch rule, though, catches more people than any single number. Your foot memorizes the first step, so a bottom step that is even half an inch off becomes a trip hazard. Inspectors measure it, and you can read the full breakdown in our guide to the North Carolina deck building code.
Stringer Lumber, Notching, and Spacing
Stair stringers are cut from 2×12 pressure-treated lumber for a reason. Once you notch out the treads and risers, you need at least about five inches of solid, uncut wood left behind the deepest notch. Start with a 2×10 and there is not enough material there to trust.
Spacing is the other half of it. Put them too far apart and the treads bounce:
- Wood treads: stringers no more than 16 inches apart, center to center.
- Composite treads: usually 12 inches apart, and some brands want 10 or even 8.
- Stairs wider than 36 inches: plan on a fourth stringer, not just the two outer ones and a middle.
Cut (notched) stringers also cannot span forever. Past roughly six to seven feet of run, they need mid-span support underneath, which is why a taller flight often lands on a small footing partway down. Our overview of NC deck footing rules covers how those pads get sized.
Landings, Handrails, and What Fails Inspection
The stairs do not end at the bottom step. Code wants a firm landing there, at least as wide as the stairs and 36 inches deep in the direction you are walking, so a concrete pad or pavers rather than bare grass.
Handrails come into play once a flight has four or more risers. They sit 34 to 38 inches above the stair nosings and have to be graspable the whole way down.
Guards along the open sides run at least 36 inches tall, with pickets close enough that a four-inch sphere cannot pass between them. NC building departments hold to those measurements closely, and the state’s deck safety guidance spells out the same stringer, guard, and handrail checks.
Stairs are also the spot most likely to send you back for a second inspection. Loose stringers, a missing handrail, or risers that vary too much are the usual culprits.
Frequently Asked Questions
What is the maximum riser height for deck stairs in NC?
7¾ inches. Every riser in the flight should land within 3/8 inch of that first one.
What is the minimum tread depth?
10 inches, measured from the front of one step to the front of the next.
What size lumber should stair stringers be?
2×12 pressure-treated. After notching, you want roughly five inches of solid wood still behind the cuts.
How far apart can deck stair stringers be?
16 inches on center for wood treads, and usually 12 inches for composite. Anything wider than a standard flight needs an extra stringer.
Do my deck stairs need a handrail?
Yes, once there are four or more risers. It sits 34 to 38 inches above the step edges.
Do the stairs need a landing at the bottom?
They do, on a solid surface at least 36 inches deep. Grass or loose soil will not pass.
Let Us Take the Guesswork Off Your Steps
Stair math is fussy, if you’d rather hand it to someone else, it’s worth comparing a few Durham deck builders before you commit. and a set of stairs that is off by a fraction is both a code problem and a daily annoyance. We handle the layout, the cuts, and the inspection so your steps feel solid the first time you walk down them, whether they are part of a new build or a deck repair on stairs that have started to sag.
Call us at (919) 638-0986 or message us here.
