How to Close Off a Half-Wall Room Divider

Pry off any molding and countertop surface that rests on top of the half-wall.

Measure the length of the half-wall and cut two 2-by-4 boards to match. These boards will be used as the top and bottom plates in the framing for the extension.

Lay the top and bottom plates on top of each other on the half-wall. Measure the distance between them and the ceiling to determine the length of the studs.

Put on safety goggles. Cut studs for the extension from 2-by-4 boards using a circular saw. Cut enough studs so that you can install them no more than 16 inches apart.

Move the top and bottom plates from atop the half-wall to a flat surface. Nail a stud into each end of the bottom plate, forming a U. Nail studs in between the two end studs, spacing them no more than 16 inches apart.

Nail the top plate to the studs along the top edge.

Place the frame for the wall extension on top of the half-wall. Nail the framing to the half-wall, the side wall and the ceiling every 6 inches.

Cut pieces of half-inch drywall with a utility knife to fit over the sides and outside edge of the end stud on the extension framing.

Screw the drywall sheets to the framing with drywall screws, using one screw every 16 inches and driving the screws deep enough that the heads go below the surface of the drywall. This allows the screws to be concealed when you finish the wall.

Nail metal corner beads to the outer edges of the extension. This provides a smoother surface on the corners.

Apply joint compound to the joints between the drywall sheets and the existing drywall, and also over the metal corner beads. Place drywall tape over the joints, pushing the tape into the joint compound with the putty knife. Allow it to dry overnight.

Sand the joints smooth with fine-grit sandpaper. Wipe the dust off of the wall with a clean, dry rag.

Apply two more coats of joint compound and drywall tape to the wall, allowing each coat to dry overnight, then sanding it before adding the next coat.

Cover the extension with a coat of primer. If you're painting the surrounding walls, and not just the extension, apply primer to them as well. Allow the primer to dry.

Apply two coats of paint to the wall, allowing each coat to dry.