How to Add a Dividing Wall to a Room

Decide on the length and thickness of the wall. Measure out this area on the ceiling and floor, using a tape measure and chalk. Locate the joists in the ceiling. Where joists run perpendicular to the new wall, fix head plates to each joist; otherwise fix the plates directly along one joist. Nail sole plates to the floor directly below each head plate, using a plumb line for guidance.

Determine the position of each stud to be placed in the wall. The first stud will be fixed to the existing wall, with a stud every 2 feet after that. Measure the height of the room at each point and cut the stud to be a tight fit; as the height may vary across the length of the room. Nail each stud in place using oval nails.

Cut lengths of studwork timber to place between the studs for reinforcement, using a reciprocating saw. These are known as "noggins," and should run along the middle of the wall, parallel to the floor. Nail the noggins in place using oval nails. Cut and nail extra noggins where heavy fixtures will be mounted on the wall, such as televisions, as these provide extra stability.

Screw drywall to the wood frame using one drywall screw every foot around the perimeter of the sheet. The sheets should be cut so they end at the mid-point on a stud, with the top and bottom of the sheet touching a head plate or a noggin. The drywall should touch the ceiling, but gaps can be left at the bottom that will be covered with a skirting board.

Apply jointing compound to the joins between the drywall sheets. Apply jointing tape over the joins, pressing it into the jointing compound. Cover the tape with more jointing compound, using a caulking tool to achieve a smooth surface. Cover the gap between the existing wall and the new partition in the same manner. Allow the compound to set. Plaster or decorate the wall as desired.