How to Do a Skirtboard for a Staircase

Stand a carpenter’s level on the topmost and lowermost treads, in turn, and mark the spot on the wall, 3 inches upward from the stair. Ensure the level reads plumb before making the marks, or adjust it if required, so it is vertical.

Snap a chalk line between both the wall marks along the stairway. The diagonal chalk line is 3 inches above each stair tread.

Hold an 8-1/2 by 11-inch sheet of paper against the upper stair tread. Adjust the paper so it rests flush against the triangular wallboard. Cut pieces of masking tape and attach it to this sheet of paper to secure it in place.

Trace the edges of the bullnose tread molding, if any, on the sheet of paper. Carefully trim excess paper off along the lines so its top falls in line with the snapped chalk line. Continue to secure pieces of paper on the wallboards adjoining each tread and marking the outlines. The sheets of paper form the templates for the stair skirting.

Tape the paper templates to each other before removing it from the wall. Spread the paper template on a 1-by-10-inch skirting stock. Tape the edges of the template to the stock to keep it from moving while you trace its outline with pencil. Carefully remove the tape and set the template aside.

Cut over the lines on the skirtboard with a circular saw. Use a handsaw to cut the inner corners.

Position the skirtboard over the treads along the stairway. Push it so it rests flush against the wall. Drive 2-inch screws to secure the skirting to the adjacent wall studs.

Cover the screw heads with tinted putty so they blend with the surface. Once the putty cures, sand it lightly to remove any bumps, giving it a smooth and even finish.