Library STEPS

Mitered box joints give rise to an updated classic

- Sarah Marriage

Ever since I was a young girl, spiral stairs have caught my fancy, and from the first time I saw a small flight of traditional library steps, I knew I wanted to build a set one day. Fast forward a few decades, and I offer you my take on this classic three-step spiral stair. Featuring coopered risers box-joined to trapezoidal treads with mitered corners, these three steps pack in a wide range of both machine and hand tool techniques. Careful, precise work will bring all your joints home at final glue up, resulting in a dazzling spiral that’s practical, too: they’re easy to move around as needed for a lift, and they stow beautifully in any corner.

Box joints with a mitered corner

Two sets of coopered risers support three trapezoidal treads that step up while rotating counter-clockwise 30° at a time. The treads are secured to the risers via box joints with overwide mitered outer fingers. (Take your time to center your box joints carefully and you’ll avoid some headaches.) The coopered risers are also biscuited for added strength and aid in alignment during glue-up. To echo the coopered faces, a hexagonal post serves as a central handrail leading up to a faceted finial, while half round cutouts at the base of the risers lighten things up and add a few contrasting curves. The post is edge-joined and biscuited onto the tallest narrow riser, and the finial is secured with a dowel. I used Kentucky Coffeetree (read all about this species in Woodsense p. 54), which resulted in a very strong and tough set of steps that are still fairly lightweight.