A worn but salvageable staircase can be rehabilitated as long as its framing is still solid and strong. Decisions have to be made whether to refinish or replace components such as the handrail and its balusters and newel posts, treads, risers and skirt board, which extends along outer face, or side, of the entire length of the staircase run. Staircases typically have a skirt board on the exposed side if the stairs extend out from a wall, or on both sides if the staircase is completely open and freestanding.
In this project, the exposed staircase side requires a new skirt board to be cut to fit. It will be installed over the existing skirt, and the original treads and risers will remain in place. The original Mission-style handrail, balusters and newel posts are first removed, refinished and replaced.
The new skirt board must be long enough to reach from top to bottom of the staircase run and wide enough to span the tread width and riser height. Typically, a 1x12" board is used. Because a staircase is often a showpiece fixture in the home, choose a quality board such as A-grade "clear" (no knots) lumber stock.
Position the board against the edge of the staircase and temporarily secure it in place.
Make a vertical mark where each of the risers meets the skirt board. Also make a horizontal mark on the board for each of the tread tops.
Remove the skirt board and lay it on a bench to readjust the marks. Move the line for each tread down one inch so the finished skirt will fit under the existing treads.
Use a circular saw to cut the riser and tread lines at a standard 90-degree angle. Start with the power saw, then finish the cut with a hand saw or jigsaw.
Test fit the skirt board against the side of the staircase. The board should fit snugly below each of the treads, and the riser cuts should be flush with the face of the original risers. It is most important that the riser cuts line up – the tread cuts don't have to be as accurate because cove moldings are typically installed below tread nosings and cover any gaps.
Use wood glue and 2-1/2" finishing nails or a pneumatic finish nailer to fasten the skirt board to the existing staircase.
Test-fit and mark the location of each tread to its specific place in the staircase. Then apply construction adhesive to the stair stringers and set the fitted treads in place (Image 1).
Use a nail gun to fasten the treads to the stringers (Image 2). If the treads are hardwood and you use a hammer and finish nails, predrill holes for the nails.
Slide the hollow newel post over the 4x4" post support base (Image 1).
Next, attach the lower end of the handrail to the post.
Refit the balusters to their appropriate places. In this staircase, there are three different lengths of spindles for each tread, and the baluster bottoms have tenons that fit into notched grooves in the treads.
Toenail the tops of the balusters into the handrail.
With all of the spindles set into the treads and into the handrail, fasten the top end of the handrail to the upper newel post (Image 2).