Like a curtain, the frame of the new wall goes into place not from the floor up, but from the ceiling down. Only in the last stage of assembly is it fastened to the floor.

In the simplest building methods, most of the frame is assembled flat on the floor. It is lifted as a unit over a beam called a sole plate that is nailed to the floor. Once upright, the wall frame is fastened into place by nails driven through a second beam, called a top plate, into the joists hidden above the ceiling. Finally, the bottom of the assembly is secured by nails driven through the sole plate.

For this final step, in which vertical beams called studs are nailed to the horizontal sole plate, you must master the knack of toenailing - that is, of fastening two pieces of lumber together at a right angle by driving a nail through them at an angle of about 45 degrees. Toenailing a stud into a plate is easy after some practice, but at first you may prefer to make a path for the toenails by drilling starter holes downward through the stud and into the plate, using a bit slightly smaller than the nail.

Ideally, the new wall should run either across the ceiling joists or under a single joist, to that the top plate can be nailed directly to a beam or beams above it. Ideally, too, the outermost stud of the new wall should lie directly against a stud in the existing wall, for easy stud-to-stud fastening. These ideal placements are not always practical. When you must run a wall between joists or end it between studs, you will have to install short lengths of wood as nailing blocks between the joists or studs to support it.

Sometimes age and traffic will have caused the ceiling or the floor joists to sag. In these cases, you may have to insert shims between the top plate and the ceiling or between the sole plate and the floor to make sure that a plate is level and firm before nailing it into place.

The other decisions you must make will affect the interior and the sheathing of the wall frame. One has to do with electrical outlets. You can install them easily in the open frame before the wallboard is installed and place them wherever you please. Usually, power for the new outlets can be taken from an existing outlet box in a nearby house circuit. Turn off the power to the circuit and make connections from the hot, neutral and ground wires in the existing box to the corresponding wires of a sheathed cable. Then run the cable through holes drilled through the new wall studs to new outlet boxes installed on the studs, secure the cable inside the boxes with clamps and strip the ends of the cable wires. Do not install new outlets back-to-back: this arrangement is common when new wiring is installed in walls because it reduces the need for wall patching, but back-to-back outlets can increase sound-carrying problems in a house.

Michael Russell

Your Independent guide to Remodelling