I built this timber frame staircase from reclaimed beams that came from another client’s house a few miles up the road. The beams were used to support a pergola that was torn down during their remodel.
We templated the area where the stairs were going to go, brought it back to the shop, and premade them. The installation was fairly straightforward as they were already assembled in sections. All that was left was to put them in place and bolt them in.
The through tenons with the wedges were, of course, as much of my work. Inspired by traditional Japanese joinery techniques.
Building Through-Tenon Stair Treads
I recently tackled a challenging woodworking project: creating stair treads with through-tenons and decorative wedges using reclaimed Douglas fir beams. The beams had already been milled and sanded to thickness, so I was ready to dive into the joinery work. Here’s how I approached this build.
Cutting the Beams to Length
I started by cutting the beams to length on my table saw. Since I needed the blade at full height for these thick pieces, safety was my top priority. I developed a technique where I use my knee to shut down the saw immediately after completing each cut, before I even think about moving the workpiece. It might seem overly cautious, but it’s become second nature to me.
Here’s the thing about this reclaimed material—it was just a little too thick for my table saw to cut all the way through in one pass. No problem. I grabbed my Japanese pull saw and finished each cut by hand. It’s one of those hybrid approaches that just works when you’re dealing with oversized stock.
The cuts weren’t perfectly flush after that two-step process, so I used a pattern bit in my router to clean everything up and make the cuts perfectly flush.
Creating the Tenons
Working with soft Douglas fir is beautiful, but it comes with a challenge: it’s prone to splintering. To keep clean shoulders on my tenons, I took the time to sever the grain with a knife before making any cuts. This simple step makes all the difference in preventing tear-out.
I cut the shoulder of each tenon to depth using my router, taking it slow and steady. Once I established those shoulders, I switched to a more aggressive bit and hogged off the rest of the material to form the tenon. This method is fast, but it leaves a lot of tool marks on the tenons.
Normally, tool marks on a tenon wouldn’t bother me since they’re hidden inside the joint. But these tenons are going to be both functional and decorative—they’ll be visible on the finished stairs. So I came back with a hand plane and cleaned them all up until they were smooth and presentable.
Sizing the Tenons
I set up the fence on my band saw to rip the tenons to width, then used my Japanese pull saw to trim off the excess material. Just like before, I used the knife scoring technique to prevent any tear-out on these visible surfaces.
Before moving on, I took a few minutes to finesse each shoulder, making sure everything was seated tightly and square to the stringers. It’s tedious work, but having tight-fitting shoulders makes the entire staircase look professional.
Cutting the Mortises
With the tenons complete, it was time to tackle the mortises in the stringers. I laid out the rise and run of the stair treads and marked out where each through mortise needed to go. Then I headed over to the drill press and used a Forstner bit to hog out most of the material.
Here’s where a little upfront work saved me a ton of time: I made a plywood template that fits perfectly over the tenons. With this template, I could use my router to quickly and accurately clean out the rest of the material from each mortise. Since my router bit wasn’t long enough to cut all the way through the thick stringers, I came back with a chisel to square up the corners and finish chopping through to the other side.
Making the Wedges
Remember all those scrap pieces I cut off from the tenons earlier? I was able to rip them down and use them to create the wedges that would lock everything together. I love finding ways to use every bit of material, especially with reclaimed wood.
To create the wedges, I set up a stop block on the band saw so I could quickly and consistently cut the decorative notch on each one. Then I positioned a wedge against the fence to cut a matching taper, completing the shape. A little cleanup on the spindle sander refined the profile nicely.
To speed up the layout process, I built a simple plywood jig that let me quickly mark out the location for the wedges on all 15 steps. Consistency is everything when you’re repeating the same operation that many times.
Creating the Wedge Mortises
For the mortises that would hold the wedges, I used my chisel trick again—staking out the perimeter first to prevent tear-out. Then I drilled out the bulk of the material and used my router to clean up the perimeter of each mortise.
Once I had the basic shape established, I returned with a chisel and carefully chopped out the rest of the material to match the taper of the wedges. This step requires patience, but it’s what makes the wedges fit snugly and look intentional.
The Finessing Phase
From this point forward, the project became an exercise in patience and precision. I spent hours driving the treads in, testing the fit, driving them back out, and removing material with chisels and hand planes. Then repeating the whole process again. And again. It’s not glamorous work, but it’s absolutely necessary to get that perfect, snug fit on all 15 steps.
The end result? A beautiful staircase with exposed through-tenons and decorative wedges that showcase both the joinery and the character of the reclaimed Douglas fir. Sometimes the old-school techniques really are the best way to get the job done.
I’m the owner of Benham Design Concepts, a mixed media art studio where I design and build custom furniture and other works of art using wood, glass, stone, and various metals.
In this blog, I talk about the art I create, my journey, and the things I learn along the way.