Plasterboard cannot be nailed directly to masonry walls, so battens of sawn timber known as furring strips are used to provide a good fixing for the nails and to counter any unevenness of the wall surface. These should be treated with a wood preserver. You can cover old plaster if it is sound, but if not strip it back to the brickwork. If damp has damaged the original plaster, it must be treated and, if possible, the area should be allowed to dry out before lining. Fix any plumbing pipe runs, electrical conduit or cable to the wall before the battens are fixed to conceal them.

Use a straightedge to mark the position of the battens on the wall with vertical chalk lines. The lines should be placed at 400mm (1ft 4in), 450mm (1ft 6in) or 600mm (2ft) centres according to the width and thickness of the plasterboard being used. Bear in mind that sheets of plasterboard must meet on the centre lines of the battens. Work away from any door or window opening and allow for the thickness of the battens and plasterboard at the reveals.

Cut the required number of furring battens from 50 x 32mm (2 x 1%in) sawn softwood. The vertical battens should oe cut 155mm (61/4in) less than the -.eight of the wall. Horizontal battens should be made to run along the tops and bottoms of the vertical ones and any short vertical infill battens above and below openings.

Nail the vertical furring battens on first, setting their bottom ends 100mm (4in) above the floor. Fix them with masonry nails or cut nails, with the face of each batten level with the guideline , and check with a straightedge and spirit level that they are also flat and plumb, packing them out as necessary.

To fix plasterboard to furring battens, follow the procedure described for nailing to a stud partition. However, the boards at the sides of windows and doors need not be notched to receive panels above or below the openings. The procedure for filling and finishing joints between the boards is identical. Cut the skirting board to length and nail it through the plasterboard to the bottom horizontal furring batten. If it is a high moulded skirting of the type used in period houses, it can be nailed to the vertical battens.

Now nail the horizontal battens across the tops and bottoms of the vertical members, inserting packing to bring them all to the same level.

Masonry walls are often uneven and, if the lining is to finish straight and flat, this must be taken into account. To check if the wall is flat, hold a long straightedge horizontally against it at different levels. If it is uneven, mark the vertical chalk line already drawn on the wall which is the closest to the point where the wall bulges most (1).

-Hold a straight furring batten vertically on the marked chalk line keeping it plumb with a straightedge and spirit level, then mark the floor (2) where the edge of the batten falls. Draw a straight guideline across the floor (3), passing through this mark and meeting the walls on each end at right angles. Align all furring battens with this line.