A prior art method of forming a mould for the casting therein of a concrete edge beam and slab of a raft foundation is shown schematically in Figure 10. In this method, a trench 1 is dug into the ground and a timber board 2 is disposed vertically at a side of the trench 1. The board requires the provision of supports (not shown) to prevent the board from toppling over under the action of the hydrostatic pressure of poured concrete. A laterally facing mould surface 3 of the timber board forms a shutter wall 2. This mould surface 3, and an upwardly facing surface 4 and a laterally facing surface 5 of the trench 1 itself, form a generally U-shaped mould for the casting therein of the edge beam 6, integrally with slab 8. In order to be able to lay bricks at a level below the surface of the ground at the edge of the trench it is necessary to avoid casting concrete right up to the top of the timber shutter wall 2.

To achieve this a sacrificial shutter 7 made of for example polystyrene or cardboard is attached to the top of the timber shutter wall on its inside mould surface 3. In this way, by removing the sacrificial shutter 7 after casting, an upwardly facing surface 9 on which a course of bricks can be laid may be formed at or below ground and/or floor level at the outer edge of the slab 8 above the edge beam 6.

A problem with this prior art shuttering method is that the shuttering is difficult to assemble, requiring carpentry skills, and requires the timber board to be properly supported if the board is not to topple over either before casting, due to back-filling of the trench 1 with excavated earth (i. e. positioning earth on the left hand side of the timber 2 as shown), or during casting due to the pressure of the poured concrete. Additionally, it is a building requirement to have a damp-proof membrane between the ground and the concrete on the side wall 3 of the mould formed by the timber shutter and on the base 4 of the trench. It is complicated to arrange a damp-proof membrane around the shutter component before pouring

concrete into the mould when a sacrificial shutter component 7 such as the one for forming the upwardly facing surface 9 for laying thereon of bricks is used.

In the first aspect of the present invention there is provided a system for assembly into a self-supporting shuttering for the casting thereagainst of a beam, the system comprising a base shutter component, a lower wall shutter component and an upper wall shutter component, the lower wall shutter component being provided with first and second locating portions, the base shutter component being provided with a third locating portion and the upper wall shutter component being provided with a fourth locating portion, whereby the first and third locating portions are engageable to locate the lower wall shutter component on the base shutter component when the lower wall shutter component is assembled on the base shutter component and the second and fourth locating portions are engageable to locate the upper wall shutter component on the lower wall shutter component when the upper wall shutter component is assembled on the lower wall shutter component, whereby the assembled shutter components form the self-supporting shuttering and wherein the first and third locating portions are adapted, when engaged, to lock said lower wall shutter component to said base shutter component and to resist any tendencies, occasioned by the action of casting the beam, of the lower wall shutter component to pivot relative to the base shutter component about the line of their engaged locating portions and of the lower wall shutter component to move upwardly relative to the base shutter component.

The hereinafter described embodiment of the present invention allows shuttering to be easily assembled from dry components without the need for motar joints or to glue or nail the components of the shuttering together. The components of the self-supporting shuttering can be carried to the site and assembled there without the need for mechanical lifting machinery. Also there is no need to attach additional sacrificial polystyrene shuttering to form an upwardly facing surface for bricks. The shuttering components allow for easy attachment of a damp-proof membrane.

In a second aspect of the present invention there is provided a self-supporting

shuttering for the casting thereagainst of a beam, said self-supporting shuttering comprising : a lower wall shutter component provided with first and second locating portions; a base shutter component provided with a third locating portion; and an upper wall shutter component provided with a fourth locating portion; wherein said lower wall shutter component is located on said base shutter component by engagement of said first and third locating portions; and said upper wall shutter component is located on said lower wall shutter component by engagement of said second and fourth locating portions and wherein the engaged first and third locating portions lock said lower wall shutter component to said base shutter component and resist any tendencies, occasioned by the action of casting the beam, of the lower wall shutter component to pivot relative to the base shutter component about the line of their engaged locating portions and of the lower wall shutter component to move upwardly relative to the base shutter component.

In a third aspect of the present invention there is provided a method of assembling a self-supporting shuttering for the casting thereagainst of a beam, the method comprising the steps of : providing a lower wall shutter component with first and second locating portions; assembling said lower wall shutter component on a base shutter component by engaging said first locating portion with a third locating portion on said base component thereby to locate said lower wall shutter component on said base shutter component; and assembling an upper wall shutter component provided with a fourth locating portion on said lower shutter wall component by engaging said second locating portion with said fourth locating portion thereby to locate said upper wall shutter component on said lower wall shutter component; and wherein in the assembled shuttering the first and third locating portions lock said lower wall shutter component to said base shutter component and resist any tendencies, occasioned by the action of casting the beam, of the lower wall shutter component to pivot relative to the base shutter component about the line of their

engaged locating portions and of the lower wall shutter component to move upwardly relative to the base shutter component.

The present invention will now be described by way of example only with reference to the following drawings in which: Figure 1 is a schematic perspective view of a first embodiment of self- supporting shuttering and foundation according to the present invention; Figure 2 is a schematic longitudinal cross-section of the lower wall shutter component of Figure 1 ; Figure 3 is a schematic longitudinal cross-section of the base shutter component of Figure 1 ; Figure 4 is a schematic longitudinal cross-sectional view of the upper wall shutter component of Figure 1 ; Figure 5 is a schematic longitudinal cross-section of a self-supporting shuttering and foundation according to the present invention; Figure 6 is a perspective view of a self-supporting shuttering according to the present invention; Figure 7 is a perspective view of a self-supporting shuttering according to the present invention; Figure 8 is a schematic longitudinal cross-section of a lower wall shutter component of a second embodiment of the present invention; Figure 9 is a schematic longitudinal cross-section of an upper wall shutter component of a second embodiment of the present invention; and Figure 10 is a schematic longitudinal cross-section through a prior art shuttering arrangement with a foundation cast therein.

The self-supporting shuttering of the first embodiment of the present invention is shown in Figure 1 can be assembled from three main shutter components which make up a system for assembly into a self-supporting shuttering for the casting therein of a concrete beam. The three main components are a lower wall shutter component 10, a base shutter component 20 and an upper wall shutter component 30.

The lower wall shutter component 10 is provided with a first locating portion 12 and a second locating portion 14 to enable it to be located on the base shutter component 20 and to enable the upper wall shutter component 30 to be located on it respectively. For this purpose the base shutter component 20 is provided with a third locating portion 22,24 which is engageable with the first locating portion 12 and the upper wall shutter component 30 is provided with a fourth locating portion 32,38, which is engageable with the first locating portion 14 of the lower wall shutter component 10. By assembling the lower wall shutter component 10 on the base shutter component 20 with the first and third locating portions engaged the lower wall shutter component 10 can be locked to the base shutter component 20, as will be described below. By assembling the upper wall shutter component 30 on the lower wall shutter component with the second and fourth locating portions engaged the upper wall shutter component 30 can be locked to the lower wall shutter component 10, as will be described below. In this way the shutter components can be assembled to form a self-supporting shuttering.

In order to enable a course of bricks to be laid subsequently on the upwardly facing surface 36 of the upper wall shutter component 30, so that the course of bricks can be at or below the level of the concrete to be cast in the shuttering, the upper wall shutter component may, as shown, be provided with supporting means 34 for supporting a top wall shutter component 40. In the illustrated embodiment the supporting means take the form of a recess 34 in the upwardly facing surface 35 of the upper wall shutter component 30. The top wall shutter component 40 is provided with means for co-operating with the supporting means. In the illustrated embodiment these cooperating means take the form of the lower edge of the top wall shutter component 40. By engaging that lower edge in the recess 34, the top wall shutter component 40 can be assembled and supported on the upper wall shutter component 30.

Preferably the upper 30 and lower 10 wall shutter components and the base shutter component 20 are fabricated in concrete, or a polymer based concrete, whilst the top wall shutter component 40 is a metal or wooden sheet. Preferably the top

wall shutter component 40 is comprised of a corrugated metal sheet to increase its stiffness and thereby reduce the thickness, weight and cost of the metal sheet required.

As can be seen from Figure 1, when assembled the shutter components 10,20,30,40 form a generally L-shaped shuttering when viewed in longitudinal transverse cross-section. The upwardly facing surface 35 of the upper wall shutter component 30 and the upwardly facing surface 16 of the lower wall shutter component 10 are elongate. The width of the upwardly facing surface 35 of the upper wall shutter component 30 in a direction perpendicular to the elongate direction of that component is larger than the width of the upwardly facing surface 16 of the lower wall shutter component 10 in the same direction. The upper wall shutter component 30 thus overhangs the lower wall shutter component 10 on both sides. In this way it is possible to minimise the weight of the components of the self- supporting shuttering whilst still enabling the self-supporting shuttering, when assembled, to present a surface along which a course of bricks 90 may be laid.

Conveniently, when the course of bricks 90 is laid along the top surface 35 of the upper wall shutter component 30, spaced away from the top wall shutter component 40, a wall cavity 92 is formed between the course of bricks 90 and the top wall shutter component 40.

A procedure for assembling the illustrated embodiment of shuttering will now be described. The initial step is to dig a generally U-shaped trench in the ground.

Next, wet mortar is placed in the bottom of the trench so that a plurality of base shutter components 20,120,220 can be laid on the mortar in a substantially horizontal plane abutting each other end to end with their third locating portions generally aligned, as shown in Figure 1. A plurality of lower wall shutter components 10,110,210 are then assembled onto the base shutter components to abut each other end to end and with their first locating portions engaging the third locating portions of the base shutter components, again as shown in Figure 1.

Finally, a plurality of upper wall shutter components 30,130,230 are assembled onto the lower wall shutter components 10,110,210 to abut each other end to end and with

their fourth locating portions engaging the second locating portions of the lower wall shutter components. In this way a longitudinal run of self-supporting shuttering can be assembled.

The strength and stability of the self-supporting shuttering can be increased by staggering the joins of the layers of components, as shown. For example, the abutted pairs of ends 100 of the base shutter components 20,120,220, are arranged such that they do not vertically align with the abutted pairs of ends 115 of the lower wall shutter components 10, 110, 210. Additionally, the abutted pairs of ends 125 of the upper wall shutter components 30,130,230 are not vertically aligned with the abutted pairs of ends 115 of the lower shutter component 10,110,210. This staggering of the joins has the effect of the upper wall shutter components and the base shutter components holding adjacent lower wall shutter components together, with a corresponding increase in strength and stability. Where the three main shutter components 10,20,30 all have the same length, for example 600 mm, the abutted pairs of ends 100 of the base shutter components, 20,120,220 and the abutted pairs of ends 125 of the upper wall shutter components 30,130,230 are preferably aligned and the abutted pairs of ends 115 of the lower wall shutter components 10,110,210 are positioned approximately half way along the length of the base shutter components 20,120,220 and the upper wall shutter components 30,130,230, as shown in Figure 1.

A laterally facing surface 70 of the trench, an upwardly facing surface 26 of the base component 20, a laterally facing surface 18 of the lower wall shutter component 10 and the laterally facing surface 36 of the upper wall shutter component 30 define a mould having a generally U-shaped cross-section. The laterally facing surfaces 70,18,36 are surfaces with at least some vertical component. Any residual trench space to the side of the lower wall shutter component 10 that is opposite to the laterally facing surface 70 may be back filled such that earth abuts the left hand side (as drawn) of the lower and upper wall shutter components 10,20.

In the first embodiment described, the locating portions are formed as locking portions to substantially prevent movement apart as well as relative sliding

movement of the lower wall shutter component 10 to the base shutter component 20 and the upper wall shutter component 30 relative to the lower wall shutter component.

As can be seen from Figure 2, the first locating portion, at one edge of the lower wall shutter component 10, comprises a triangular shaped lip-receiving recess 12 which runs adjacent the edge of the generally elongate slab shaped lower wall shutter component 10 on the moulding surface 18. The third locating portion of the base shutter component 20, as shown in Figure 3, comprises a recess 22 in the moulding surface 26 of the base shutter component 20 running adjacent, but spaced apart from, an edge with a generally triangular shaped lip 24 protruding laterally into the recess 22. The protrusion of the lip 24 into the recess causes the lip to overhang the base of the recess 22. The top surface of the lip is flush with the moulding surface 26.

During assembly of the self-supporting shuttering in the trench, after arranging the base shutter component (s) generally horizontally, the first locating portion is placed into the recess 22 in a base shutter component 20 whilst an acute angle is maintained between moulding faces 18,26 of the lower wall shutter component 10 and the base shutter component 20. The lower wall shutter component 10 is then pivoted around its first locating portion relative to the base shutter component 20 (in an anti-clockwise direction as drawn) to increase the angle between the moulding faces 18,26 and thereby to engage the lip 24 of the third locating portion in the lip-receiving recess 12 of the first locating portion 10. In the illustrated embodiment the lower wall shutter component 10 is pivoted by an amount such that the moulding faces 18,26 of the lower wall shutter component 10 and of the base shutter component 20 end up substantially perpendicular to one another. It will however be appreciated that for a forming beam of other cross-sectional shapes, the moulding faces of these two components need not be substantially perpendicular to one another. In such an alternative arrangement, the geometry of the locating portions would require modification.

The engagement of the laterally protruding lip 24 in the lip-receiving recess

12 means that the lower wall shutter component 10 is locked to the base shutter component 20 to resist the tendency for lateral sliding movement, as well as upward movement, of the lower wall shutter component 10 relative to the base shutter component 20, as well as resist further pivoting of the lower wall shutter component 10 relative to the base shutter component 20 occasioned by the action of casting the beam. When casting a concrete beam, hydrostatic forces can be quite high and the laterally protruding lip 24 engaging in the lip-receiving recess 12 resists the action of these forces. To make assembly easier, the recess 22 in the base shutter component 20 may be made oversize, necessitating the insertion of a spacer element into the back of the recess 22 between the base shutter component 20 and the lower wall shutter component 10 on the side opposite the moulding surface 18 to help to jam the lower wall shutter component 10 into the recess 22 of the base shutter component 20.

These spacer elements may, for example, be wedges fabricated in wood, concrete or any other suitable material.

The second locating portion of the lower wall shutter component 10, as shown in Figure 2, comprises a laterally protruding lip 14 which extends beyond the moulding surface 18 of the lower wall shutter component 10 to overhang the base shutter component 20 and is of generally a triangular cross-section. In this way, the first and second locating portions are provided on opposite longitudinal elongate edges of the moulding surface 18 of the generally slab-shaped lower wall shutter component 10.

The fourth locating portion 32 of the upper wall shutter component is shown in Figure 4 and comprises a lip-receiving lateral recess 32 for receiving the laterally protruding lip 14 of the second locating portion. The lip-receiving lateral recess 32 is formed in a portion of the upper wall shutter component 30 which, in use, overhangs the base shutter component 10 and extends down the moulding surface 18 of the lower wall shutter component 10.

A back lip 38 may, as shown, be provided as part of the fourth locating portion on the upper wall shutter component 30 to co-operate with the back surface of the lower wall shutter component, this back surface being the surface opposite to

the moulding surface 18 when assembled. In use, the back lip 38 can help to lock the upper wall shutter component 30 to the lower wall shutter component 10 to prevent misalignment and sliding movement of the upper wall shutter component 30 relative to the lower wall shutter component 10.

In the first embodiment, once the lower wall shutter component 10 has been pivoted into final position, the upper wall shutter component 30 may be assembled on the lower wall shutter component 10. If the optional back lip 38 is provided on the upper wall shutter component, as is illustrated in Figures 1 and 4, assembly is achieved by first orientating the upper wall shutter component 30 such that its moulding surface 36 is positioned to face the laterally facing wall 70 of the trench and the back lip 38 is close or in contact with the upwardly facing surface 16 of the lower wall shutter component. The upper wall shutter component 30 is then moved relative to the lower wall shutter component in a direction away from the laterally facing wall 70 of the trench until the back lip 38 can engage behind the back surface of the lower wall shutter component 10. This happens by a pivoting action of the upper wall shutter component 30 around the lip receiving lateral recess 32 and lip 14.

If there is no back lip, as denoted by the dotted lines in Figure 4, the upper wall shutter component 30 may be assembled on the lower wall shutter component by being slid into place without the above-mentioned pivoting action.

When engaged, the laterally protruding lip 14 and lip-receiving lateral recess 32 resist the tendency of the upper wall shutter component 30 to move laterally (to the left as drawn) as well as upwardly relative to the lower wall shutter component 10 occasioned by the action of casting of a beam in the generally U-shaped mould.

It will be appreciated that the locating portion may be configured differently to those in the illustrated embodiments and still have the effect of holding the various shutter components together to enhance overall stability of the assembled shuttering.

The depth of the trench and the height of the main shutter components may be adjusted such that the upwardly facing surface 35 of the upper wall shutter component 30 is substantially level with or below the edge of the trench. In this way, the outer bricks 90 of a building can start at or below the level of the ground which is

aesthetically more appealing than having concrete visible above the level of the ground.

If it is desired to integrally form a slab 60 of a raft foundation with the beam to be cast in the trench, with the slab having an upwardly facing surface above the level of the upwardly facing surface 36 of the upper wall shutter component 30, the top wall shutter component 40 is assembled onto the upper wall shutter component 30. This arrangement allows a course of bricks to be laid below the level of the upwardly facing surface of the raft as well as at or below the edge of the trench.

Once the upper wall shutter components 30 have been assembled onto the lower wall shutter components, the top wall shutter components 40 can be assembled onto the upper wall shutter components 30 by inserting edge portions of the top wall shutter components 40 into the recesses 34 in the upwardly facing surfaces 36 of the upper wall shutter components 30 to support the top wall shutter components 40. This enables the height of the shuttering to be sufficient to cast a beam and a slab of a raft foundation whilst still presenting an upwardly facing surface 36 at or below the edge of the trench along which a course of bricks 90 may be laid and below the level of the slab 60.

The shutter wall components are preferably made both of a material and of a size such that the components of the self-supporting shuttering can be readily carried by one or two people and easily assembled without the need for special skills. The weight of each component is advantageously under 50 kg, preferably less than 30 kg.

The components may be cut by an angle grinder. To simplify the action of staggering the joins of the different layers of the main shutter components, the main shutter components 10,20,30 are all of the same length, for example 600 mm long in their an elongate direction (dimension'X'in Figure 1). The base shutter component may be 450 mm wide and 15 mm thick. The lower wall shutter component may be 75 mm thick and 240 mm high. The top wall shutter component may be 115 mm thick at its maximum thickness and 190 mm wide at its maximum width. When assembled, the upper wall shutter component 30 may extend the height of the shuttering by about 65 mm. It is envisaged that the main shutter components will all

be at least 0.3 m long, that the base shutter component 20 will be at least 0.2 m wide and 0.01 thick, that the lower wall shutter component will be at least 0.3 m high and 0.01 m thick and that the maximum height of the upper wall shutter component will be at least 0.05 m and the maximum thickness will be at least 0.15 m. It will be appreciated that the components may readily be supplied in other sizes and/or materials.

Using the shuttering assembled in a trench, a beam 50 can be cast in the generally U-shaped mould integrally with the slab 60 of a raft foundation assembly.

The upwardly facing surface of the raft 60 may be used to form the floor of a building. To enable the formation of a cavity wall, a further course of bricks (not shown) may be built on the edge of the slab 60, and the built up like course 90, to form a pair of parallel walls with a cavity therebetween.

Current building regulations require that the foundation of a building is damp-proofed against water ingress from the ground. In Figure 1, a damp-proof membrane 80 (denoted by a dotted line) is placed along the entire surface of the generally U-shaped mould as well as along the ground onto which the slab 60 of the raft foundation is to be cast. The damp-proof membrane may also extend beyond the top of the top wall shutter component 40 to lap with a damp-proof course which would be laid under the internal skin of the building as described below in conjunction with Figure 5.

An alternative arrangement to the one illustrated in Figure 1 is to damp-proof the shutter wall components by painting them with bituminous paint. In such a case a damp proof membrane laid on top of the ground onto which slab 60 is to be cast is lapped to base shutter component 20. This arrangement can also be used without applying bituminous paint to the main shutter components 10,20,30 if those components are made of a material which is substantially impermeable to water, for example a polymer based concrete.

The modular nature and ease of assembly of the illustrated embodiment of self-supporting shuttering allow the shuttering to be assembled without the need for fasteners or various glues. It is anticipated that the beam and raft foundations which

can be cast using the illustrated embodiment of self-supporting shuttering will be able to meet today's building regulations for one and two storey buildings and when used in conjunction with a piling system would be suitable for almost any building.

Figure 5 shows an embodiment of the invention in which several further features, which may be used together, individually or in any combination have been incorporated.

In order to minimise the possibility of relative movement between the base and lower wall shutter components 20,10 during casting of the beam, as shown a lower wedge or lower wedges 210 can be driven into the recess 22 of the third locating portion on the opposite side to lip 24 and abutting the lower wall shutter component 10 to lock the first locating portion in the recess 22 of the third locating portion.

Similarly, an upper wedge or upper wedges 220 can be driven between the back lip 38 of the fourth locating portion and the lower wall shutter component 10 thereby to assist in preventing relative movement between the upper and lower wall shutter components 10,30 during casting of the beam.

A metal clip can also be used, if necessary, to improve the resistance of the assembled main components 10,20,30 to toppling over prior to the casting of the beam. The clip 230 is of a generally U-shaped construction and, when attached to the assembled main components, engages the base shutter component on a face 28 which is on the other side of the base shutter component to the moulding surface 26 and the upwardly facing surface 35 of the upper wall shutter component 30.

Conveniently the metal clip 230 can be removed after the casting of the beam and prior to back filling of earth against the shutter wall components.

It is also possible to manufacture the lower wall shutter component 10 integrally with reinforcing members 250 protruding from the moulding surface 18 into the area into which the beam is to be cast. In the illustrated embodiment these take the form of a plurality of closed loops of metal in spaced apart relationship to each other along the elongate direction of the lower wall shutter component 10. As will be understood, any shape or configuration (eg spiral) of reinforcing members

250 can be utilised. If required, links 260 (eg in the form of bars) may be attached to the reinforcing members to maintain the spacing of the reinforcing members 250 in the elongate direction of the lower wall shutter component 10. Also, supporting blocks 270 may be used to transfer the load of the reinforcing members 250 to the base shutter component 20 before casting of the beam to support the reinforcing members 250. If reinforcing members 250 are used, which are preferably steel, damp proofing of the shuttering may be achieved by applying liquid bituminous paint to the shutter components 10,20,30. This can either be applied at the manufacturing stage or after assembly of the shuttering. The use of reinforcing elements 250 advantageously provides shear reinforcement between the precast shutter components and the final cast beam.

The raft 60 of the foundation may, as illustrated in Figure 5, also be reinforced by raft reinforcing members 280,290 supported by reinforcing members 250. If the foundation is to be supported by piles, these are positioned under the base shutter component 20 in a position approximately as indicated by 300 in Figure 5.

If the shuttering is supported by piles, the optimum position for the raft reinforcing members is lower (position 280) than the optimum position (position 290) for the case where the foundation is not supported by piles.

A course of bricks 304, above ground level, built on top of the course of bricks 90 is separated from the course of bricks 90 by a damp-proof membrane 3. An inner course of bricks 300 is built on a top surface of the raft 60 of the foundation.

The inner course of bricks is also damp-proofed from the foundation by a sheet 305 which is lapped to the damp-proofing of the main shutter components, for example to the damp proof membrane 80.

The skilled person will recognise that there are several ways in which the shuttering can be arranged to accommodate changes in direction. Two examples are shown schematically in Figures 6 and 7.

Figure 6 shows how the direction of the shuttering might be changed through a small angle. Standard base and lower wall shutter components 20,10 (as described above in relation to Figures 1 to 4) can be used, albeit cut to shape. In this regard

two corner base shutter components 20'are cut along the moulding surface 26 and perpendicular thereto such that, when the cut ends of the two corner base shutter components 20'abut each other, their third locating portions lie at the desired angle to each other. The ends of the corner lower wall shutter components 10'are cut to the desired angle (i. e. not perpendicular to the moulding surface 18) such that those cut ends abut each other when the corner lower wall shutter components 10'are assembled onto the corner base shutter components 20'.

The corner upper wall shutter component 30'is manufactured as a single component and is essentially in the shape of two upper wall shutter components joined together at an angle end to end. It comprises all of the features of the standard upper wall shutter component mentioned above except for one of either back lip 38 or recess 32, such that it can be assembled onto the two corner lower wall shutter components 20'without rotation. As in the embodiment shown in Figure 1, the main shutter components 10,20,30 are staggered in the longitudinal direction to improve strength. This is achieved by the choice of length of the corner shutter components 10', 20', 30'.

Figure 7 illustrates a further method of changing the direction of the shuttering. The base shutter components 20 are all standard (i. e. as discussed in relation to Figures 1 to 4) and uncut. Two longitudinal runs of base shutter components 20 come together with their third locating portions at approximately 90° to each other. The corner lower wall shutter component 10"is generally L-shaped with only the base of the L-shape provided with a first locking portion which engages with the third locking portion of one of the base shutter components 20. The corner upper wall shutter component 30"is also generally L-shaped and is otherwise the same as corner upper wall shutter component 30'. The size of the corner components are preferably chosen such that the main components are longitudinally staggered to increase the strength of the assembled shuttering.

Figures 8 and 9 respectively show a lower wall shutter component 410 and an upper wall shutter component 430 of a second embodiment of the present invention.

The lower and upper wall shutter components 410,430 of the second embodiment

may be used with a base shutter component 20 shown in Figure 3 of the first embodiment of the present invention.

The lower wall shutter component 410 of the second embodiment differs from the lower wall shutter component 10 of the first embodiment in three major ways. First, with regard to the first locating portion, the lower wall shutter component 410 of the second embodiment has a protruding lip 412 rather than a lip receiving recess 12. The protruding lip 412 slots underneath the lip 24 of the third locating portion of the base wall shutter component 20.

The second difference is that the outer surface 417 which is opposite the moulding surface 418 is not parallel to the moulding surface 418. In fact the outer surface 417 is at an angle to the moulding surface 418 such that an overhang 419 is formed at the first locating portion of the lower wall shutter component 410 of the second embodiment. The overhang 419, when the lower wall shutter component 410 is located on the base wall shutter component 20, engages with and rests on the moulding surface 26 of the base wall shutter component 20. This means that the engagement of the protruding lip 412 of the lower wall shutter component 410 with the lip 24 of the base wall shutter component 20, as well as the engagement of the overhang 419 and the moulding surface 26, resist the tendency of the lower wall shutter component 410 to pivot relative to the base shutter component 20 about the line of their engaged locating portions occasioned by the action of casting the beam.

In fact, it is possible that the downwardly facing surface of the first locating portion (i. e. the lowest surface as illustrated in Figure 8) may be inclined at an angle (for example, perpendicular to the outer surface 417). Such an angle also helps in resisting the tendency to pivot occasioned by the action of casting the beam.

In the embodiment illustrated in Figure 8 the outer surface 417 is in a single plane. This is not necessarily the case. The outer surface 417 may be mainly parallel to the moulding surface 418 and the overhang 419 may only be formed at the first locating portion by protrusion of the outer surface 417 locally.

The third difference between the lower wall shutter component 410 of the second embodiment and that of the first embodiment is in the second locating

portion. Here an upwardly facing surface 416 is inclined at an angle (i. e. it is not perpendicular to the moulding surface 418 as is the case in the first embodiment).

The direction of slant is such that when the upwardly facing surface 416 comes into contact with the upper wall shutter component 430, a component of the force is in the direction towards where the beam is to be cast. In this way, the angle of the upwardly facing surface 416 helps resist the tendency of the upper wall shutter component to pivot relative to the lower wall shutter component about the line of their engaged locating portions occasioned by the action of casting the beam.

Other changes to the shape of the lower wall shutter component 10 apart from those illustrated in Figure 8 are possible. For instance, certain shape changes may be advantageous in order to help the casting of the lower wall shutter component itself.

Any combination of features described and illustrated is possible.

The upper wall shutter component 430 illustrated in Figure 9 has a fourth locating portion adapted for use with the lower wall shutter component 410 illustrated in Figure 8. As can be seen from Figure 9, the upper wall shutter component 430 of the second embodiment has a lateral recess 132 which is similar to the lateral recess 32 of the first embodiment. The upper wall shutter component 430 of the second embodiment also has a back lip 438 similar to the one illustrated as optional in Figure 4. One of the major differences is that the wall 433 between the lateral recess 132 and the back lip 438 is at an angle which corresponds with the angle of the upwardly facing surface 416 of the lower wall shutter component 410.

As stated above, this angle ensures that a component of the force between the upper and lower shutter wall components is in the direction towards where the beam is to be cast and will help in resisting the tendency to pivot caused by the action of casting the beam.

The upper wall shutter component 430 of the second embodiment is also designed for easy moulding of the upper wall shutter component 430 itself. This is achieved by providing side walls 435 and 437 inclined towards one another rather than parallel to one another as is illustrated in Figure 4. These inclined surfaces aid in the extraction of the upper wall shutter component 430 after casting in a mould.

The side wall 435 which forms part of the moulding surface against which a beam is cast, may be inclined in the opposite direction to that illustrated in Figure 9. Such an inclination results in a downwards force being exerted on the upper wall shutter component 430 when cement is cast against the assembled shuttering. Such a downwards force helps to resist the tendency of the upper wall shutter component 430 to float off the lower wall shutter component.

Many modifications may be made to the three main components of the shuttering. These include changes in dimensions and shape which might depend upon which materials are used to manufacture the components.