Cornices formed from gypsum based settable materials are known. In one commercially available cornice of this type, reinforcing in the form of teased sisal is embedded in the gypsum based settable material to increase the strength of the cornice. Generally, apart from being fairly time consuming, the manufacture of such a cornice is relatively difficult and requires skilled or semi-skilled labour. In addition, these cornices tend to be relatively thick in order to accommodate the teased sisal, and consequently are comparatively expensive to manufacture.

Another type of cornice currently available is formed from a gypsum based settable material carrying glass fibres in the form of chopped strands. An advantage associated with this type of cornice is that it is easy to manufacture. However, these cornices tend to be weak, especially when subjected to shear stresses, and often break under relatively low lateral loads. It is an object of the present invention to provide an alternative method of moulding a cornice from a gypsum based settable material which does not require skilled or semi-skilled labour, and which can be used to produce relatively high strength cornices at a comparatively low cost.

SUMMARY OF THE INVENTION According to the invention there is provided a method of manufacturing a cornice comprising the steps of : providing first and second elongate mould members which are arranged to define an open-topped, open-ended mould cavity when connected to one another; locating an end stop at each of the ends of the first elongate mould member, the end stops being designed to form a seal between the ends of the elongate mould members when the members are connected to one another; securing at least one fibrous strand to the two end stops to provide one or more lengths of strand which extend across the first mould member from one end stop to the other; connecting the second mould member to the first mould member to define an open-topped mould cavity across which the one or more lengths of strand extend; introducing into the mould cavity a gypsum based settable material to form a cornice; allowing the settable material to set; separating the second mould member from the first mould member; separating the end stops from the cornice; and removing the cornice from the first mould member.

In a preferred embodiment of the invention, the gypsum based settable material includes fibre reinforcing, typically in the form of glass fibres.

Preferably, the method includes the step of vibrating the mould formed by the two elongate mould members after the gypsum based settable material has been introduced into the mould cavity and before the settable material sets to remove air pockets from within the settable material.

Each of the elongate mould members may include a timber frame and a mould face formed from a plastics material such as fibreglass supported on the timber frame.

Typically, the mould face for shaping an operatively concealed face of the cornice includes formations for forming longitudinal and transverse ribs on this face of the cornice. In a preferred arrangement, at least one of the ribs is aligned with the one or more lengths of strand. Conveniently, the end stops are formed from a synthetic rubber and include a plurality of openings through which the ends of the at least one fibrous strand can be threaded.

In one arrangement, the first elongate mould member includes recesses which are shaped and sized to receive locating projections on the end stops.

The edges of the end stops may be shaped to form interlocking formations on edges of cornices formed in accordance with the method of the invention so that the cornices are interlockable with one another end to end.

Preferably, the at least one fibrous strand comprises one or more glass fibre strands.

The invention also provides for a cornice formed from a gypsum based settable material carrying glass fibres, the cornice including at least one reinforcing fibrous strand which extends along the length of the cornice from a first longitudinal end thereof to another, and at least one reinforcing rib on one of the faces of the cornice.

In a preferred embodiment, the cornice has a longitudinal rib and a plurality of transverse ribs extending along an operatively concealed face of the cornice.

Typically, there are three pairs of fibrous strands embedded in the cornice, one pair of which is arranged to run along the length of the cornice so as to be aligned with the longitudinal reinforcing rib.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows an exploded perspective view of a mould for forming a cornice in accordance with the method of the present invention; Figure 2 shows a perspective view of a portion of the mould illustrated in Figure 1 in an inoperative, open condition; Figure 3 shows a cross-sectional view of the mould illustrated in Figure 1 in an operative, closed condition; and Figure 4 shows a perspective view of a portion of a cornice formed in accordance with the method of the invention.

DESCRIPTION OF AN EMBODIMENT In Figure 1 of the drawings there is shown a mould 10 for forming a cornice in accordance with the method of the present invention. As can be seen, the mould 10 essentially comprises first and second elongate mould members 12 and 14 which are connectable to one another to form a mould cavity.

The first, lower mould member 12 has a mould face 16 which is formed from a plastics material, typically fibreglass, and which is supported on a timber frame generally designated with the reference numeral 18. The frame 18 comprises two timber planks 20 and 22 which are arranged substantially orthogonally with respect to one another, and a further timber plank 24 connected to the planks 20 and 22 to form a base for the mould face 16, as shown.

In Figure 1 of the drawings the mould face 16 can be seen to stop short of the end of the timber frame 18 thereby to expose a portion of the timber plank 24 at each end of the mould member 12. Each of the exposed portions of the plank 24 (only one of which is shown in Figure 1) defines two locating recesses 26 for locating a synthetic rubber end stop 28 on the mould member 12. The end stops 28 include locating projections (not visible) on the underside thereof which are sized and shaped to fit within the recesses 26.

Each end stop 28 also defines six openings 30 which are arranged in three pairs, as illustrated.

The plank 24 carries a plurality of spaced-apart screws 32 which project from the upper face of this plank. The heads of the screws 32 are tapered, as shown most clearly in Figure 3, and facilitate the bonding of the mould face 16 to the plank 24.

The second mould member 14 is similar in many respects to the first mould member 12 and also includes a timber frame comprising two timber planks 34 and 36 arranged substantially orthogonally with respect to one another, and a plank 38 forming a base for a mould face 40. Unlike the first mould member though, the mould face 40 extends to the ends of the second mould member 14 without leaving end portions of the plank 38 exposed.

With reference also to Figures 2 and 3 of the accompanying drawings, the method of manufacturing a cornice according to the present invention will now be described.

Initially, the first mould member 12 is placed on a substantially level surface (not illustrated) with the plank 22 resting on the level surface and the plank 20 projecting upwardly away from this surface. The synthetic rubber end stops 28 are then located at the ends of the first mould member 12 by inserting the locating projections on the end stops into the recesses 26 in the plank 24. One of the end stops is illustrated in this position in Figure 2.

At least one glass fibre strand is then threaded through the openings 30 in the end stops 28 and is secured so as to form three pairs of strands 42 which extend over the mould face 16 from one end stop to the other, as shown in Figure 2. If desired, an oil for facilitating the removal of the cornice once moulded may be applied to the mould face 16 before the strands 42 are installed.

Thereafter, the second mould member 14 is fitted over the first mould member 12 in the manner illustrated in Figure 3 and the two mould members are clamped together in a conventional manner to define a mould cavity 44. As can be seen in Figure 3, the mould formed by the two mould members 12 and 14 defines an opening 46 in an upper wall thereof which leads into the mould cavity 44. The end stops 28 are slightly thicker than the gap which they fill between the first and second mould members 12 and 14 so that as the first and second mould members are brought together to form the mould cavity 44, the end stops are compressed between the two mould members and seal off the end regions of these mould members.

In this condition, the mould formed by the mould members 12 and 14 is ready to receive material for moulding the cornice. A gypsum based settable material including glass fibres, typically in the form of chopped strands, is then introduced into the mould cavity 44 through the opening 46. Once the cavity 44 has been filled with the settable material, the mould is vibrated to release air pockets from within the settable material. In this embodiment of the invention, a vibrating table is used to vibrate the mould.

Thereafter, the settable material is allowed to set, the mould is stripped by removing the second mould member from the first mould member and detaching the end stops from the moulded cornice, and the cornice is then removed from the first mould member.

Figure 4 illustrates a cornice 50 produced by the method of the present invention. In this Figure, the cornice 50 can be seen to include a longitudinal rib 52 and a series of transverse ribs 54 (only one of which is shown) which have been formed by surface formations on the mould face 40 and which extend along an operatively concealed surface of the cornice. These ribs serve to strengthen the cornice, thereby allowing the average thickness of the cornice to be relatively small, and this in turn allows for material savings. Typically, the longitudinal rib 52 is arranged so as to be aligned with the middle pair of fibrous strands, as shown in Figure 4. It should be appreciated that the mould used in the method of the present invention is relatively easy to assemble and disassemble and that unskilled labour could be used to form cornices in accordance with the method of the invention. Also, by reinforcing the cornice with ribs and fibrous strands, the average thickness of the cornice can be reduced so as to be relatively small when compared with conventional cornices.

Accordingly, the method of the present invention allows a gypsum based cornice which is comparatively strong to be manufactured relatively easily and cheaply.