Trimming Curved Stairs
Site-laminated handrails, flexible skirtboards, and off-angle miters are standard on winding walkways.
Synopsis: Trim carpenter Jason Mollak is used to trimming basic stairs, but he always enjoys the extra challenge of working on curved stairs. In this article, he lays out the steps he takes, from bending the handrail, to installing a flexible PVC skirtboard, to dressing up the treads and risers, to prepping and fitting the handrail.
Most of the whole-house finish carpentry my crew tackles includes basic stair packages — skirtboards, false treads for the ends of the rough risers and treads, one or more newels, and a handrail with balusters. So it’s a nice change of pace when we’re thrown a curve.
While I don’t recommend that your first set of stairs be curved — or even your fifth — the skills needed to do this work aren’t new to finish carpenters, the process is just slightly different than that of a standard stair. Rather than treads with a consistent depth, you’re faced with pie-shaped treads. The 45° miters on open-stringer nosings on a standard stair are replaced with off-angle cuts to bridge the curvature of the skirtboard, which must be bent to fit the ascending curve of the stairway rather than just following a simple rise and run on a standard stairway. The key to all of this curved work is to think of the framed stairway as your template. Following this method, and using materials suited for the job, your task is simply to bend, measure, and fit the pieces to the curved template provided by the framers.
It’s common practice here in Nebraska for stairs to be fully carpeted, so the framers usually set the stage with particle-board treads that have a rounded front edge. But many jobs, including this one, are trimmed to accommodate false tread ends and a swath of carpet that mimics…