The present invention relates to precast concrete building panels such as are used in the construction of the walls of buildings. Many forms of precast building panel have been proposed and are in use. The object of the present invention is to provide a concrete building panel which is simple to produce by precasting in a mould, which has all the required characteristics for such panels and in addition provides a barrier against the passage of moisture, additional reinforcement of the sheet and, where a lining material such as fibrous plaster sheets to the inner face of the panel.

The present invention consists in a precast concrete building panel consisting of a slab having a plane exterior face and an interior face from which project a series of parallel longitudinally extending ribs spaced apart across the width of the panel the inner end faces of the ribs being aligned, each of said ribs being capped by a channel section member of metal or plastic material. The term "plane exterior face" is to be taken to include faces to which some decorative treatment has been applied and which are therefore not strictly plane.

In order that the nature of the invention may be better understood preferred forms of the invention are hereinafter described by way of example with reference to the accompanying drawings, in which: -

Figure 1 is a perspective view of a precast concrete building panel according to the invention; Figure 2 is a cross-sectional view thereof;

Figure 2a is a sectional view to an enlarged scale of one rib;

Figure 3 is a cross-sectional view of an alternative rib shape; and Figure 4 is a cross-sectional view of a mould in

which a panel according to the invention can be cast.

A panel according to the invention is made in concrete or reinforced concrete utilising any suitable conventional concrete mix or method of reinforcing. The panel consists of a slab 10 having a substantially smooth plane outer face 11. The face 11 may be the subject of any desired superficial decorative treatment. Reinforcing steel (not shown) is included in the slab in accordance with normal design requirements. The rear face 12 of the slab 10 has projecting from it a plurality of ribs 13 cast integrally with the slab 10. Appropriate reinforcing steel is included if necessary in each of the ribs. Each rib 13 is capped by means of a metal or plastic channel section member 14 extending over the end and a substantial portion of the sides of each rib. The inner end faces 15 of the ribs 13 are aligned and all lie in the same plane so that a sheet of lining material such as fibrous plaster may be applied to the interior of the panel. The normal requirements for the fixing of such sheets is that they be secured by means of at least two screws arranged near the centre of the panel the remainder of the panel being secured by gluing. The metal or plastic channel section members enable this to be done. In the particular case illustrated a projecting flange 16 is fixed to the channel section member 14 on the central rib 13 near the middle of the rib to which the lining sheet may be secured by screwing. The remainder of the sheet is secured to the inner end faces 15 of the channel section members 14 J?y gluing. Horizontal bracing members may be secured as required between the ribs 13 as illustrated and 17 and such a bracing member could also be used as a means for securing a lining sheet.

The construction of the panels is by casting in a mould, the channel section members 14 being incorporated

in and forming part of the mould.

The ribs 13 need not be parallel sided as illustrated in Figure 2 but may be shaped as shown in Figure 3 in which case the channel section member is correspondingly shaped.

The vertical edges of the panel may be provided with tongues such as that shown at 18 and grooves such as that shown at 19 to facilitate the connection of panels edge to edge in a building. Figure 4 shows a cross-sectional view of a mould in which a panel according to the invention can be cast. The mould includes longitudinally extending channels 21 and 22 which are adapted to receive metal or plastic rib covering members 23 and 24. In a practical construction these would be of the same cross-sectional shape. In Figure 4, however, they are shown as being of different shapes to illustrate different possibilities for the cross-sectional shape of rib covering member, the member 23 being of "top-hat" section and the member 24 being of cuneiform or wedge shaped section. It is to be noted that both the members 23 and 24 have lateral extensions overlying the bottom surface of the mould. In an alternative form of construction the rib covering members may be formed from a single sheet of material which will thus cover the whole of the surface of the mould.

In addition to the rib covering members there is placed in the mould, metal or plastic side members which act to define the edges of the mould. It is to be noted that whereas the left hand member 25 as feen in Figure 4 is shaped to form a protruding tongue 27 the member 26 is shaped to form a corresponding groove 28. This enables panels to be laid side by side with the tongue of one panel fitting to into the groove of the adjacent panel.

In an alternative form of construction the member 25, for example, may be formed in one piece with the adjacent

member 23.

The panel is formed by placing suitable reinforcing in the mould and casting concrete around it to form a panel with a plane face but with the rib covering members and the edge members incorporated in the panel.

Panels constructed according to the invention are simple to make, relatively light in weight and provide what is in effect a cavity wall construction.

The metal or plastic channel section members have a three-fold effect. Firstly, they act as a barrier for the transmission of moisture through the panel to any lining material attached to the inner face of the slab. They provide additional reinforcement to the slab and can be taken into account when calculating the amount of internal reinforcement required for a particular slab. Finally, where a lining material is used in conjunction with the slab they provide a ready means for attachment of the lining material.

The panels according to the invention may be constructed in a wide variety of different configurations within the scope of the invention as defined above, the particular forms of the invention described are by way of illustration only.