How to Remodel a Stairway to the Basement Using a Half Wall

Remove any existing rough railings on the side of the stairway where you want to install the partial wall. Usually, these are installed with framing nails and can be easily removed with a claw hammer. Examine the staircase carefully to make sure it is in good repair and that it was constructed as a permanent structure.

Measure the side of the staircase from the front riser to where the new partial wall will end. Usually, the half wall will merge into the existing ceiling of the basement as the wall angles upward. The actual wall may continue at ceiling height to the beginning of the staircase.

Measure the width of each tread. It is likely that the treads will vary. Look for the shortest tread. Measure 1/2 inch for drywall beyond the edge of the tread. Drop a plumb bob over your location and mark the exact spot on the concrete. This is the distance from the side of the staircase for your stud placement.

Lay a 2-by-4-inch board along the floor, starting where you want the wall to begin and stopping where you want the wall to end. Make sure the board is parallel to the staircase. Apply painter's tape around the perimeter of the board on the floor, as a guide.

Cut sheet plastic to cover the concrete at your tape outline. Wood should never rest directly against concrete. Cut and place a 2-by-4-inch board flat inside your outline. Shoot masonry nails through the wood into the concrete. You can rent a masonry nail gun at home improvement stores. Attach a fastener every 24 inches.

Cut two 2-by-4-inch boards 42 inches long. Position the boards on top of the wood plate at the bottom of the staircase. Square the ends. Toenail the bottom of the upright board into the floor plate with a framing nail gun. Nail the second board to the first. Measure from the top of the staircase treads, looking for the exact spot where the distance is 32 inches from the tread to the bottom of the ceiling joist. Mark the spot. Measure from the top of the lowest tread 32 inches on your upright set of boards. Mark the lowest point.

Hold a board up along your two marks and check that the angle matches the angle of the staircase. Mark the board with the ceiling cut angle. Mark the double board post with the top cut angle. Make your cuts with a circular saw. Fit the board into position and mark the outside cut on the board. Cut the outside cut. Nail the board into position from the double post to the ceiling joist.

Measure away from the center line of your inside upright board 16 inches and mark the floor plate. Mark every 16 inches. Stand up a stud on the floor plate centered on the 16-inch mark and mark the angle of the wood on the stud, using the top board as a guide. Cut the stud with a table saw or circular saw. Center the stud and make sure it is vertically straight. Toenail and downward nail the stud to the floor plate and top board. Repeat for each stud.

Add blocking between the outside of the staircase stringer and the stud wall to help make the wall stronger. It may also be necessary to add blocking between your ceiling joist for good attachment points.

Remove the stair treads and risers before installing your drywall. Unscrew the treads. Slide your drywall between the new wall and the stringers. Screw the drywall to the new wall, using drywall screws. Install the outside drywall by cutting the drywall to fit and screwing the wall board to the studs. Butt edges along studs.

Measure, cut and fit your treads and risers to fit snug to the drywall. You may want to upgrade the wood to hardwood quality if you are finishing the basement.

Apply outside corners to the bottom edge of the drywall. Cut the edging with tin snips. Screw the edging to the drywall with drywall screws. Spread joint compound over all drywall screw heads, using a wide drywall knife. Apply flexible mesh tape over the seams. Fill, blend, smooth and scrape off any excess compound.

Measure 1-by-6-inch board to fit over the top of the wall. The board should overhang all sides evenly. Cut the board to length. Create a contoured finished edge, using a router. Apply construction adhesive to the back of the board, and glue the board to the top of the wall. Add finish nails for additional security.

Measure and miter-cut the ends of quarter round wood trim to trim out the underside of the wood cap. Install the quarter round with adhesive and finish nails.