How to Build Stairs: Mastering the Art of Vertical Navigation in Your Home

Stairs represent one of humanity's most elegant solutions to a fundamental problem—moving between different levels efficiently while maintaining structural integrity. Every time I walk up a well-crafted staircase, I'm reminded that these aren't just functional elements; they're architectural poetry that marries mathematics, physics, and craftsmanship into something we use without thinking twice. Building stairs yourself might seem daunting at first glance, but once you understand the underlying principles, it becomes less mysterious and more like solving a three-dimensional puzzle where every piece has a purpose.

The Mathematics Behind Every Step

Before touching a single piece of lumber, you need to embrace the numbers. Stair building revolves around two critical measurements: rise and run. The rise is the vertical distance between steps, while the run is the horizontal depth of each tread. These aren't arbitrary—they're governed by both building codes and the biomechanics of human movement.

Most building codes specify that risers should be between 7 and 7.75 inches high, with a maximum variation of 3/8 inch between the tallest and shortest riser in a flight. Treads typically need to be at least 10 inches deep. But here's what the codes don't tell you: there's an ancient formula that carpenters have passed down through generations. Two risers plus one tread should equal between 24 and 25 inches. This isn't just tradition—it reflects the natural stride length of most adults.

I learned this the hard way when I built my first staircase with risers that were technically within code but felt awkward to climb. The stairs were legal but uncomfortable. That experience taught me that building stairs isn't just about following rules; it's about understanding why those rules exist.

Planning Your Staircase Like a Chess Master

Start by measuring your total rise—the vertical distance from the lower floor to the upper floor. Don't just measure once. I measure at least three points along where the stairs will go because floors aren't always perfectly level. Use the largest measurement to ensure your stairs will work everywhere.

Divide your total rise by 7.5 inches to get a rough number of steps. If you get 13.4, you'll need either 13 or 14 risers. Now divide your total rise by each option to find your exact riser height. Choose the one that gives you a riser height closest to 7.5 inches.

Here's something most DIY guides gloss over: your top step is actually the upper floor itself. So if you need 14 risers, you'll only build 13 treads. This trips up more beginners than any other aspect of stair building.

Once you know your riser height, calculate your tread depth using that old formula. If your risers are 7.25 inches, your treads should be about 10.5 inches (25 - 14.5 = 10.5). This creates a comfortable rhythm for climbing.

Choosing Materials That Won't Let You Down

The stringers—those diagonal supports that hold everything together—need to be strong enough to carry significant weight without flexing. I prefer using 2x12 lumber for stringers, though 2x10 can work for shorter runs. Southern yellow pine offers excellent strength for the price, though Douglas fir remains the gold standard if your budget allows.

For treads, you want something that can handle daily abuse. Solid hardwood looks beautiful but costs a fortune. Pine treads work fine if you're planning to carpet. For painted stairs, I've had great success with laminated pine treads—they're stable, affordable, and take paint well.

One material choice that surprises people: I often use engineered lumber for stringers in challenging installations. Yes, it costs more, but engineered lumber won't warp or twist over time, which can turn a perfect staircase into a squeaky nightmare after a few years.

Laying Out Stringers Without Losing Your Mind

Stringer layout separates amateur hour from professional results. You'll need a framing square, and not just any square—invest in a good one. Those $15 squares at the hardware store might be fine for rough framing, but stair building demands precision.

Attach stair gauges to your square at your rise and run measurements. These little clamps turn your square into a specialized stair-laying tool. Starting at one end of your stringer board, position the square so both gauges touch the edge. Mark along both edges of the square. Slide the square along until the rise mark aligns with your previous run mark. Repeat until you've marked all your steps.

The bottom of your stringer needs special attention. You'll cut off a portion equal to your tread thickness so your first step isn't taller than the others. The top gets a similar treatment, with cuts that allow it to attach properly to your upper floor framing.

Cutting Stringers: Where Precision Meets Reality

Cutting stringers intimidates people, and rightfully so. One wrong cut can ruin an expensive piece of lumber. I always cut my first stringer, then use it as a template for the others. This ensures consistency even if my initial measurements were slightly off.

Use a circular saw for most cuts, but stop short of the corners. Finish with a handsaw to avoid overcutting, which weakens the stringer. Some builders use a jigsaw for the corners, but I find a sharp handsaw gives cleaner results.

After cutting your first stringer, test fit it in place. This is your last chance to catch errors before committing to the full set. Check that your rise and run are consistent, and that the stringer sits properly at both top and bottom.

Assembly: Where Planning Pays Off

Installing stringers requires patience and often a helper. The outside stringers go up first, attached to the wall framing with lag screws or structural screws. Don't skimp here—use fasteners rated for the load. I space them every 16 inches vertically.

The middle stringer (for stairs over 30 inches wide) floats between the outer ones. Some builders skip this, but I've seen too many bouncy staircases to take that shortcut. Support the bottom of all stringers properly—a 2x4 kickplate secured to the floor works well.

Installing treads seems straightforward, but technique matters. I glue and screw from underneath whenever possible, which hides fasteners and creates a cleaner look. Construction adhesive on every connection point reduces squeaks—apply it liberally but neatly.

For risers, the debate rages on whether to install them before or after treads. I prefer installing risers first, as it creates a backing for the treads and looks cleaner from below. Others swear by treads first. Both methods work if executed properly.

The Details That Separate Good from Great

Nosing—that little overhang at the front of each tread—serves both aesthetic and safety purposes. A 1-inch nosing is standard, though I prefer 1.25 inches for a more substantial look. You can buy treads with pre-milled nosing or add it yourself with a router.

Speaking of routers, easing the edges of your treads isn't just about looks. A small roundover on the nosing prevents splintering and feels better underfoot. It's a five-minute detail that pays dividends for years.

Consider adding a subtle back-bevel to your treads—about 1/8 inch from back to front. This nearly imperceptible slope helps water run off and makes the stairs feel more secure when descending. Most people never notice it consciously, but their feet appreciate it.

Building Codes and Common Sense

Every jurisdiction has specific requirements for stairs, and ignoring them invites both danger and legal troubles. Handrail height, baluster spacing, and headroom clearance aren't suggestions—they're requirements backed by decades of safety data.

That said, some code requirements seem arbitrary until you understand their origins. The 4-inch sphere rule for baluster spacing? That's based on the size of a young child's head. The 6'8" headroom requirement? That accounts for tall people carrying objects up the stairs.

I've found that exceeding code minimums often results in better stairs. If code requires 36-inch-high handrails, I might go to 37 inches for taller clients. If treads must be 10 inches minimum, I'll push for 11 when space allows.

Troubleshooting When Things Go Sideways

Even experienced builders encounter problems. Uneven floors throw off calculations. Walls aren't plumb. Material dimensions vary. The key is catching these issues early and adapting.

If your risers come out slightly uneven despite careful planning, distribute the error across all steps rather than having one oddball. A series of 7.4-inch risers feels better than mixing 7.5-inch and 7-inch risers.

Squeaky stairs plague many installations. Prevention beats cure—use construction adhesive liberally during assembly. For existing squeaks, driving screws from below often solves the problem. Sometimes you need to shim between treads and stringers to eliminate movement.

The Satisfaction of Self-Built Stairs

Building your own stairs transforms how you see every staircase. You'll notice clever solutions in public buildings, appreciate fine craftsmanship in historic homes, and yes, silently judge poor construction everywhere you go.

More importantly, you'll have created something fundamental—a safe, functional path between levels that will serve for decades. Every trip up and down reinforces the satisfaction of building something substantial with your own hands.

The first time someone compliments your stairs without knowing you built them? That's when you know you've succeeded. They're not being polite—they're responding to something that feels right because you took the time to understand not just how to build stairs, but why they're built that way.

Remember, stairs aren't just about getting from point A to point B. They're about creating a rhythm, a flow through space that feels natural and safe. When you build stairs properly, people use them without thinking. That invisibility is the highest compliment your work can receive.

Authoritative Sources:

Ching, Francis D.K., and Cassandra Adams. Building Construction Illustrated. 6th ed., John Wiley & Sons, 2020.

International Code Council. 2021 International Residential Code for One- and Two-Family Dwellings. International Code Council, 2020.

Spence, William P. Residential Framing: A Homebuilder's Construction Guide. Sterling Publishing, 2004.

U.S. Department of Housing and Urban Development. "Stairways." Residential Rehabilitation Inspection Guide, www.hud.gov/sites/documents/DOC_12487.PDF

Wagner, John D. Building Stairs. The Taunton Press, 2003.