The Ultimate Guide to Building Custom Stairs: My Step-by-Step Process
(This is the fifth in a 10 part series. Credit: Akribis Leather. Luke Riemer, owner, was the framing contractor we hired for our build. The project consisted of a carriage house, garage extension with suite above, and renovation/expansion of the existing residence. All 3 phases of the project had some timber framing elements. Text below is a cleaned up transcript of the video above)
Building stairs might seem straightforward, but it’s one of those elements in a house that truly defines craftsmanship. Over the years, I’ve built hundreds of stair sets, refining my method with each project. In this post, I’ll walk you through my process for building high-quality, durable stairs that are precise, solid, and easy to finish.
Understanding Your Stair Requirements
For this particular project, I was working with:
- Wall height: 8 feet
- Floor system thickness: 11-7/8 inches
- Stairs with a landing in the middle (turn halfway up)
The first step in stair construction is calculating the total rise. I measured from the top of the subfloor I was standing on to the subfloor above, giving me a total rise of 109-5/8 inches.
Flooring materials impact rise calculations. In this project:
- Bottom floor: in-floor heated tile, 3/4-inch thickness
- Upper floor/stairs: vinyl, 1/4-inch thickness
Subtracting the difference, my adjusted total rise was 109-1/8 inches.
Determining Risers and Treads
To calculate the number of risers, I divided the total rise by 7-1/2 inches, a comfortable riser height in North America. This resulted in 14 risers, each measuring just over 7-3/4 inches.
The run (tread depth) was specified on the plans as 10 inches. Since I was adding finished flooring and nosings later, the stairs themselves would be square, with no nosings installed.
Summary of counts:
- 14 risers at 7-3/4 inches each
- 13 treads at 10 inches each
- Landing replaces one tread
The landing height was calculated by multiplying the riser height by the number of risers to the landing, giving a precise fit.
I split the stair construction into two sets:
- Bottom set: 8 risers, 7 runs
- Top set: 6 risers, 5 runs
Materials I Use
Over the years, I’ve switched from 2x12 stringers to 1-3/4-inch LVL because it doesn’t cup, twist, shrink, or warp. While slightly more expensive, it’s extremely strong and worth it.
- Stringers: 1-3/4" × 11-7/8" LVL
- Treads: 1-inch standard-grade plywood
- Risers: 3/4-inch plywood
- Blocking: 2×2 at tread/riser intersections
Laying Out the Stringers
I start by setting up a framing square with stair gauges. Accuracy here is critical: if your gauges are off, rises and runs grow or shrink, and the stairs won’t be level.
- Bottom set: 8 risers, 7 runs
- Add 1/2 inch to the bottom rise for thicker flooring
- Subtract 1 inch at the top for plywood tread thickness
- Remove 3/4 inch from the last run to accommodate plywood hanging
I repeat the same process for the top set, making adjustments for the top riser and plywood thickness.
I cut one stringer first, then use it as a template for the other two. This ensures all three stringers are identical. Some people stack and cut all three at once, but even a slightly misaligned saw blade can ruin your alignment.
Cutting Treads and Risers
- Treads: Cut from 1-inch plywood. Length with a circular saw, width on a table saw for accurate laps.
- Risers: Cut from 3/4-inch plywood. Set stair width 1-1/2 inches narrower than the stairwell opening.
Spacers on either side allow drywall to slide in later. Centers are marked to ensure stringers stay parallel and plumb.
The bottom two risers are unique, as they account for differences in floor thickness and the lack of a riser beneath.
Hanging and Securing Stairs
I hang stairs using 3/4-inch plywood as a backer. The stringers butt into the backer, glued and screwed, and the stairs hang from it.
- Snap lines for rise and run, accounting for tread and floor thickness
- Glue all risers
- Install treads in place, securing with screws at stringers and blocking
- Use screws from the back while still accessible to fine-tune alignment
Once installed, stairs are solid, square, and free of squeaks or bounce.
Finishing Touches
- No nosings are installed at this stage; they will be added with finished flooring.
- After treads are anchored, everything is checked for alignment, and screws are added into studs for additional security.
Why I Build Stairs This Way
Stairs are often the framer’s signature. The way they are built says a lot about attention to detail and overall quality. My method may be overbuilt for some, but it’s a system that works—hundreds of times over.
This approach ensures durable, safe, and perfectly aligned stairs that make installation of finishing materials easy and professional-looking.
