We recently devised a method for trimming enclosed staircases that resulted in gap-free intersections between the treads, the risers and the skirtboards. Here’s how we did it. Before installing the 1/4-in. veneered plywood skirtboards, we stapled a layer of 1/8-in. foam to the walls behind the skirts. The foam allowed enough give so that we could then install all the treads and the risers — cut 1/6 in. oversized — and get a perfect fit all the way up the staircase. If a small gap turned up somewhere, we drove a thin wedge between the plywood and the foam. Then we capped the exposed edge of the plywood with a piece of solid wood trim.
Howie Roman, Whaletown, None