You can build the new ceiling at any height providing it complies with the regulations. However, the height of window openings may limit your choice. About 2.4m (8ft) is a useful height for a lowered ceiling. It is a common room height for modern houses and relates to standard wallboard sheet sizes. Most manufacturers of built-in furniture adopt it as a standard height for ceilings.
Planning the layout
Making a lowered ceiling requires a considerable amount of timber for the framework and boarding to cover it. Work out your material requirements by drawing a plan to establish the most economical way to construct it. If you intend to use plasterboard choose a vapour-check type. Arrange the panels with the paper-covered edges set at right angles to the timber supports. Stagger the end joints between each row of boards and arrange them so as to fall on a joist.
If you plan to use tongued and grooved boarding, buy it in lengths that can be economically cut to suit your joist arrangement, as short off-cuts are wasteful. Avoid butt joints coinciding on adjacent boards.
Materials for the framework
Make a cutting list of the materials you will need to make up the structure. Use 75 x 50mm (3 x 2in) sawn softwood for the ceiling joists. These should span the room in the shortest direction. Calculate the number of joists you will need. These should be spaced at 400mm (1 ft 4in) or 600mm (2ft) centres according to the thickness of the plasterboard. These dimensions will also suit other types of boarding.
You will need extra joist timber for the noggings fitted between the joists. In addition 50 x 25mm (2 x 1 in) sawn softwood is used for wall battens to run round the perimeter of the room.
Spans of over 2.4m (8ft) should be supported by hangers and ties, made from timber not less than 50 x 50mm (2 x 2in) which are fixed to the ceiling above. Place the hangers about the middle of the joists’ span.
It is possible to use more hangers and reduce the section of the joists from 75 x 50mm (3 x 2in) to 50 x 50mm (2 x 2in). In this case place the hangers about 1m (3ft) apart.
Constructing the ceiling
Mark the height of the new ceiling, including the thickness of the boarding, on one wall. At this level draw a horizontal line across the wall using a straightedge and spirit level for accuracy. Continue the line around the room at this height. Cut the 50 x 25mm (2 x 1 in) wall battens to length. Nail or screw them to the walls at 400mm (1 ft 4in) intervals, with the bottom edge level with the line.
Cut the 75 x 50mm (3 x 2in) ceiling joists to length. Notch the ends to sit over the wall battens to bring the bottom edges flush. Skew-nail the joists to the wall battens. Cut and fit hangers and ties to prevent long joists sagging. These supports also stiffen the structure.
Cut and nail noggings between the joists to support the edges of the plasterboard. Nail tapered-edge plasterboard to the joists, noggings and wall battening. Fill and tape the joints between boards and walls.
Lowering part of a ceiling
You can lower part of a ceiling to overcome problems around tall window openings or to create a split-level effect. Follow the method for constructing a ceiling as described above but enclose the end drop with plasterboard nailed to hangers fixed in a line to a cross-tie member set above the last joist.
Making a slatted ceiling
Planed softwood planks 150 x 25mm (6 x 1 in) in size, set on edge and spaced apart can create a simple yet effective slatted ceiling. Smaller sections can be used where the span is short, as with a narrow hallway.
Cut four lengths of planking to line the walls all round. Before nailing or screwing them at the required height, mark and cut housings in two of the planks opposite one another. Space the housings 225mm (9in) apart. For boards less than 150mm (6in) wide, space them about 100 to 150mm (4 to 6in) apart. Cut notches in the ends of the ‘slat’ boards to sit in the housings so that the bottom edges finish flush.
Before fitting the slats, paint walls and ceilings above the lining boards with a dark emulsion paint. Also paint ducting or plumbing to disguise it. Finish the slats with varnish, stain or paint.