Prefabricated building panels

Abstract

A pre-fabricated panel 12 comprising a rigid backing 10 and a plurality of slips 14 adhered thereto, the backing having at least one step portion 26, 30 which, in use, underlaps the backing of an adja

Description

Prefabricated Building Panels This invention relates to prefabricated building panels suitable for providing a wall surface on the exterior or interior of a building. More particularly, the invention concerns building panels including a plurality of building elements, such as shaped building pieces or blocks, arranged in courses in spaced apart relationship forming joint gaps occupied by mortar. Precast prefabricated concrete building panels incorporating building pieces or blocks in the form of so-called slips which may be cut from, or shaped out of, larger standard-sized blocks and cast into a concrete backing are known. Such slips may be formed from concrete, clay, brick, tile, terracotta, stone, reconstituted stone or architectural masonry. Brick is particularly preferred because it simulates aesthetically a brick wall whilst substantially reducing the building costs normally incurred with bricklayers. The panels can simply be placed in the desired position in the building structure, suitably fixed in that position and the joint gaps between the slip courses and between the end side edges and top and bottom edges of the adjacent panels filled with the same mortar. Such building panels are heavy, require expensive machinery to lift into position and because of their weight are not suitable for providing wall surfaces in timber-framed buildings in locations where there is no support from the ground. With a view to overcoming the disadvantages of precast slip-surfaced building panels for timber framed buildings, the applicant has developed a prefabricated slip-surfaced building panel in which the slips are adhesively bonded to a substantially rigid backing leaving a narrow peripheral lip in the backing projecting outwardly of and extending along the top and bottom edges and side end edges of the building panel. The panels are fixed to the timber frame to provide the wall surface with the backing lips of the side edges of adjacent panels and top and bottom edges of adjacent panels respectively in edge to edge abutment forming butt joints between the adjacent panels. The width of the narrow backing lips is such (typically 5mm) that when the backing lips are in edge to edge abutment, the combined width of the abutting lips between the assembled panels forms a joint gap (typically 10mm) between the adjacent panels of the same width as the joint gaps between the slip courses. Then, the joint gaps between the slip courses of the same panels and between those of adjacent panels are filled with the same cement mortar to complete the wall surface. Whilst such slip-surfaced building panels are of significantly lighter weight than the precast building panels and thus can be handled manually without recourse to expensive machinery and can be used unsupported in timber framed buildings, other problems have arisen in use. These problems concern lack of stability in walls formed from the slip- surfaced bonded building panels causing inter alia loss of water-tightness. This is due to movement occurring at the butt joints between the backing lips of adjacent panels because the-edge-to-edge butt contact area is small and can result in cracking of the cement mortar between the adjacent panels. Thus, there is an ever present risk of ingress of water by capillarity through the cracks and into the timber framed structure. This movement is not helped by the use of generally planar backings which although substantially rigid overall, may have a degree of flexibility in the region of the butt joints. Also, the narrow edge-to-edge butt contact area between the backing lips of adjacent panels does not readily accommodate movements that naturally occur in timber framed buildings, further contributing towards cracking of the mortar at the butt joints. Lack of stability can also cause misalignment of the panels and with time be detrimental to the overall aesthetic effect of the wall surface. Accordingly, the main object of the present invention is to provide a slip- surfaced bonded building panel for timber-framed buildings in which the aforesaid disadvantages are prevented or at least substantially avoided. To this end, the present invention resides in a prefabricated building panel having oppositely facing side edges and top and bottom edges, a substantially rigid backing having front and rear surfaces, the backing being provided with a plurality of laterally extending reinforcing ridges projecting from its rear projecting from its rear surface in parallel spaced apart relationship, a plurality of slips adhesively bonded to the front surface of the backing in a plurality of courses leaving joint gaps for the reception of mortar in same width spaces between the courses and the slips of each course, the backing also being provided with depressions which are formed by a step portion extending continuously beyond the slips along the top edge and along one of the side edges of the backing and providing a top edge step portion and a side edge step portion, and by rearward facing projections in the rear surface of the backing and lying in the same plane as that of the peaks of the ridges, the front surface of the backing having an area that is oversized compared to the area of the backing front surface covered by the bonded slips, leaving a narrow peripheral lip of the backing exposed immediately adjacent the slips and extending all the way around the bonded slips, the narrow lip having a width that is substantially one half that of the joint gaps between the slips, such that when a plurality of such building panels are assembled to form a wall surface, adjacent portions of the narrow lip along the top and bottom edges and oppositely facing side edges of adjacent building panels are brought into edge-to-edge abutment and the top edge step portion and side edge step portion respectively underlap the backings along the bottom edge and opposite side edge of two adjacent such building panels thereby to enable alignment of the front faces of the slips of adjacent assembled panels. By means of the underlapping backing of the invention with the step portion providing the top edge step portion and the side end edge step portion extending continuously along the top edge and along one of the side edges of the backing, stability of the building panels is increased in the joint gaps between adjacent assembled panels, such that cracking of the mortar filling the joint gaps between the adjacent building panels and thus the ingress of water into the building by capillary action through the cracks are at least substantially prevented. Stability is further improved by the laterally extending reinforcing ridges, the depressions forming the top and side edge step portions which also enable alignment of the front faces of the slips of adjacent assembled panels, and the depressions also formed by the rearward facing projections in the rear surface of the backing and lying in the same plane as that of the peaks of the ridges further improve stability and ease of fixing to the timber frame of the building. The front surface of the backing having an area that is slightly oversized compared to the area of the backing front surface covered by the bonded slips with the narrow peripheral lip of the backing left exposed immediately adjacent the slips ensures that the joint gaps between the siips of adjacent panels are of the same width as those between the slips of those panels. To accommodate adjacent top and bottom edge portions respectively of the backing and ensure alignment of the exposed front surfaces of the slips, the backing conveniently has diametrically opposite top and bottom corner regions provided with cut-outs respectively to accommodate adjacent top and bottom edge portions respectively of the backing of adjacent assembled panels. Advantageously, the ridges are in the form of corrugations whose peaks form the ridges that lie in a plane that is parallel to that of the rear surface and whose troughs open onto the front surface of the backing, thereby enabling the backing to be of substantially uniform thickness throughout which reduces the amount of material used to make the backing and therefore cost In a preferred embodiment of the invention, the slips are adhesively bonded to the front surface of the backing in a plurality of courses with at least one slip per course and with spaces of the same width between the slips providing joint gaps for the reception-of mortar and wherein the backing projects alternately to each side of the backing by substantially the length of one half slip to form a substantially vertical series of alternating laterally facing recesses and projections with the recesses and projections on one side being opposite the laterally facing projections and recesses respectively on the other side. The mortar may be cement mortar, epoxy mortar or any other suitable mortar. Ease of locating fixings, and thus ease of fixing the building panels to the timber frame of a building may be facilitated by aligning the corrugations opening onto the front surface of the backing with selected ones of the joint gaps between slip courses. Manual handling of any of the prefabricated building panels defined above may be facilitated by providing the side step portion of the backing with notches between the slips. The invention also comprehends a wall surface provided by a plurality of any of the prefabricated building panels defined hereinabove and a building having at least one such wall surface. In order that the invention may be more readily understood, some embodiments in accordance therewith will now be described, by way of example, with reference to the accompanying drawings, in which:- Fig. 1 is a front elevation of a backing for a prefabricated building panel constructed in accordance with the invention: Fig. 2 is a rear elevation of the backing of Figure 1; Fig. 3 is a perspective view from the front and left-hand, as illustrated, side edge of the backing of Figure 1; Fig. 4 is front elevation of a building panel bearing a multiplicity of slips laid in eight courses with five slips per course and fixed to the front surface of the backing of Figures 1 to 3; Fig. 5 is a perspective view from the front and left-hand side, as illustrated, of the building pane! of Figure 4; Fig. 6 is a perspective view from the rear and left-hand side, as illustrated, of the building panel of Figures 4 and 5; Fig. 7 is a left-hand side edge view of the building panel of Figures 4 to 6; Fig. 8 is a left-hand side edge view of the building panel of Figures 4 to 7; Fig. 8a is a vertical section to an enlarged scale through the building panel of Fig. 5 showing the construction of the backing: Fig 8b is a detail view of the vertical section of Fig.8a to greater enlarged scale; Fig. 9 is a top edge view of the building panel of Figures 4 to 8 and 8b; Fig. 10 is a bottom edge view of the building panel of Figures 4 to 8, 8b and 9; Fig. 11 is a picture of four building panels in front elevation like that of Figures 4 to 6 showing how the building panels are assembled together in adjacent side edge to side edge relationship and top edge to bottom edge relationship to form a wall surface: Fig. 12 is a detail view to an enlarged scale in picture format of two adjacent building panels like those in Figure 11 of parts of the top edges and side edges of the two adjacent panels in side edge to side edge relationship to show more fully how such building panels are assembled; Fig. 13 is a detail perspective view to an enlarged scale in picture format taken from the top and left-hand side, as illustrated, of a building panel like the right-hand, as illustrated panel, in the picture of Fig.12 to show the construction of the backing in the region of the top left-hand side, as illustrated, of the building panel of Figure 5; Fig. 14 is a front elevation of a prefabricated building panel like that of Figure 4 in having eight courses of slips but differing from that of Figure 4 in having four slips per course; Figs.15 and 16 are front and rear elevations respectively of the backing of the building panel of Figure 14; Fig. 17 is a front elevation of a prefabricated building panel like that of Figure 4 in having eight courses of slips but differing from that of Figure 5 in having three slips per course; Fig. 18 and 19 are front and rear elevations respectively of the backing of the building panel of Figure 17; Fig. 20 is a front elevation of a prefabricated building panel like that of Figure 4 in having eight courses of slips but differing from that of Figure 5 in having two slips per course; Fig. 21 and 22 are front and rear elevations respectively of the backing of the building panel of Figure 20; Fig. 23 is a front elevation of a prefabricated building panel like that of Figure 4 in having eight courses of slips but differing from that of Figure 5 in having one slip per course; Fig. 24 and 25 are front and rear elevations respectively of the backing of the building panel of Figure 23; Fig. 26 is a front elevation of a prefabricated building panel like that of Figure 5 in having eight courses of slips but differing from that of Figure 5 in having alternating half slip and one slip courses: Figs. 27 and 28 are front and rear elevations respectively of the backing of the building panel of Figure 26; Figs. 29, 30, 31, 32 and 33 show the building panels of Figs. 4, 14, 17, 20 and 23 respectively in picture format, Figs. 34, 35, 36, 37, 38 and 39 are perspective views in picture format of eight slip course internal and external corner building panels for suiting different requirements and utilising an alternating half slip and one slip formation on opposite sides respectively of the corners; Figs. 40, 41, 42 and 43 are perspective views in picture format of external corner building panels utilising eight half slip courses to the right hand and left hand sides and alternating half slip and one slip courses to the left hand and right hand sides of Figs. 40 and 43 respectively and alternating half slip and one slip courses on both left hand and right hand sides of Figs. 41 and 42 respectively; Figure 44 is a perspective view of a timber-framed building showing the timber frame and having partially and completely finished wall surfaces provided by a selection of the prefabricated building panels illustrated in Figures 4 to 43; Figures 45, 46 and 47 are a front elevation, a perspective view from the front and left-hand side, as illustrated, and a perspective view from the rear and left-hand side, as illustrated, of a modification of the backing of Figures 1 to 3, and Figures 48, 49 and 50 are a front elevation, a perspective view from the front and left-hand side, as illustrated, and a perspective view from the rear and left-hand side of a building panel bearing a multiplicity of slips laid in eight courses with five slips per course and fixed to the front surface of the backing of Figures 45 to 47. In the drawings, the same reference characters are used to designate the same or similar parts. Referring to the drawings, Figs. 1 to 3 show a backing 10 forming part of a prefabricated building panel 12 shown in Figures 4 to 13. The building panel 12 is of generally rectangular shape and incorporates a multiplicity of slips 14 adhesively bonded to the front surface 15 of the backing 10 in eight courses 16 with five slips 14 per course, leaving joint gaps 13 in the same width spaces between the courses 16 and the slips 14 of each course. The backing 10 may be made of any suitable material or materials consistent with the backing 10 having sufficient rigidity to provide a dimensionally stable support for the slips 14 without sacrificing the lightness of weight essential to ensure ease of manual lifting, positioning and fixing of the building panel 12 to form a wall surface with other such building panels 12 (see also Figures 14 to 43) and which is also cost-effective. The backing material is advantageously formed from a sheet of substantially uniform thickness and can be of a metal such as steel or aluminium. However, for reasons of cost and simplicity of construction, the backing 10 is advantageously made from a generally rectangular sheet of plastics material. In this connection, the Applicant has found that moulded glass-reinforced plastics (GRP) has the requisite characteristics and is currently the plastics material of choice for the backing 10. Rigidity and consequentially stability of the backing 10 and thus of the entire building panel 12, is enhanced by the provision of four reinforcing ridges 17 projecting from the rear surface 18, and extending lengthwise, of the backing 10 in parallel spaced apart relationship. The ridges 17 are in the form of corrugations with the peaks forming the ridges 17 that project from the rear surface 18 of the backing 10 and the troughs of the corrugations indicated at 19 in Figures 1a and 2 are formed in (open onto) the front surface 15 of the main body 21 of the backing 10. The corrugated construction forming the ridges 17 and troughs 19 enables the backing to be of substantially uniform thickness throughout, thereby reducing the amount of plastics material used for the backing 10 and thus the overall weight and cost. Moreover, the corrugations facilitate ease of locating fixings Accuracy of laying and bonding of the slips 14 in the courses 16 is facilitated by scoring a grid 20 of lines (shown as broken lines in Figs. 1 and 3) on the front surface 15 of the main body 21 of the backing 10. As shown in Figs. 1 to 3, the backing 10 projects alternately to each end side edge beyond the main body 21 for substantially the length of one half slip to form, on one end side A, the left-hand end side, as illustrated, in Figs. 1 and 3, (the right-hand end side, as illustrated, in Fig. 2), a substantially vertical series of alternating sideways (laterally) facing recesses 22 and projections 23 in the backing 10. On the opposite end side B, the right-hand hand end side as illustrated in Figs. 1 and 3, (the left hand end side, as illustrated in Fig. 2), there are alternating outwardly facing recesses forming depressions 24 and projections 25 in the backing member 10 which are opposite the projections 23 and recesses 22 respectively. The depressions 24 are formed by a side edge step portion 26 of the backing 10, which step portion 26 projects peripherally outwardly beyond main body 21 on the right hand side B as illustrated in Figs.1 and 3 (the left hand side A as illustrated in Fig. 2) and rearwardly beyond the rear surface 18 as indicated at 27 of the backing 10 as will be more readily appreciated from Fig. 2a. The step portion 26 stops short of the bottom edge 28 of the backing (bottom side D) to form a cut-out 29 and is continuous with a top edge step portion 30 extending peripherally beyond the main body 21 (top side C) to form the top edge 32 of the backing 10 and rearwardly beyond the rear surface 19 as indicated at 34 in Fig. 2a and Figs 8a and 8b. As with the side edge step portion 286, the top edge step portion 30 stops short of the left hand side edge of the backing 10, as illustrated in Figs. 1 and 3, (right hand side edge in Fig. 2), to form a cut-out 36. The apices of the rearward extensions 27 and 34 of the side edge and top edge step portions 26 and 30 lie in the same plane (extend for the same distance rearwards) as the reinforcing ridges 17 (see Figs. 8a and 8b). Following the score line grid 21, the slips 14 are bonded in broken bond, using a suitable adhesive, to the front surface 15 of the backing 10 in eight courses 16 with five slips 14 per course leaving the joint gaps 13 which are typically 10mm wide to produce the building panel 12 shown in Figures 4, 5,6, 7, 8, 9, 10, 11, 12 and 13. Applicant has used successfully a two part resin-based adhesive called SIKADUR 31 manufactured by Sika Products to bond the slips 14 to the backing 10. However, any other suitable adhesive may be used. To enhance adhesion of the slips 14 to the backing 10, the front surface 20 of the backing 10 may be suitably treated e.g. by being textured or otherwise roughened or prepared {not shown) to receive the slips 14. It will be appreciated that the projections 23 and 25 of the backing 10 each support half of a slip 14 in the building panel 12. The area of the front surface of the backing 10 is slightly oversized compared to the actual area of the front surface of the backing 10 covered by the bonded slips 14 in the building panel 12 of Figures 4 to 13, sc that a narrow peripheral lip 40 of the backing 10 is left exposed immediately adjacent the slips 14 and extends all the way around the bonded slips 14. The narrow lip 40 is shown in double-width black lines for clarity of illustration and is typically 5mm wide, i.e. one half of the 10mm joint gaps between the bonded slips 14. Thus, to assemble a plurality of the building panels 12 shown in Figs. 4 to 10 to form a wall surface, with particular reference to Fig. 11 as well as Figs. 10a, 12 and 13, the projections 23 (side A), each bearing half of a slip 14, of an adjacent building panel 12 are aligned with the depressions 24 (side B) and the projections 25, (side B), the projections 23 (side A), each bearing half of a slip 14, are aligned with the recesses 22 (side A) of the adjacent building panel 12 with the adjacent portions of the narrow lip 40 adjacent the bonded slips 14 being brought into edge-to-edge abutment with each other and with the side edge step portion 26 underlapping the backing 10 beneath the projections 23. Similarly, the adjacent portions of the narrow lip 40 along the top and bottom edges 32 and 28 adjacent the bonded slips 14 of adjacent panels 12 are brought into edge-to-edge abutment with each other so that the top edge step portion 30 on top side C underlaps the backing 10 along the bottom edge 28 on bottom side D. The cut-out 36 accommodates the top corner edge region of the step portion 30 of the right hand as illustrated panel 12 (see Figure 12) and the cut-out 29 accommodates the bottom edge 28 in the bottom corner region of the backing 10 to preserve alignment of the front surfaces of the slips of a multiplicity of adjacent assembled panels 12. Thus, the top and side edge step portions 30 and 26 form a continuous strip portion of the same width throughout its extent sufficient to provide an underlap with the backing 10 of adjacent building panels 12. The edge-to-edge abutting narrow lips 40 on oppositely facing sides A and B and top and bottom sides C and D of adjacent panels create 10mm joint gaps between adjacent panels which are of the same width as the joint gaps 13 between the slips 14. The embodiments of building panels 12a, 12b, 12c and 12d illustrated in Figures 14, 17, 20, and 23 respectively differ from that of Figures 4 to 6, only in that the backings 10 are progressively of reduced lateral extent as will be appreciated from Figs, 14 to 16, Figs 17 to 19, Figs 20 to 22 and Figs. 23 to 25 to accommodate each of the eight courses 16 of four slips 14, three slips 14, two slips 14 and one slip 14 respectively. The embodiment of building panel 12e of Figs. 26 to 28 differs from the embodiments of Figs. 4 to 6, Figs 14 to 16, Figs. 17 to 19, Figs. 20 to 22 and Figs. 24 and 25 in that there are alternating half slip (unreferenced) and full slips 14 in the eight vertical courses 16 and in that the vertical left hand surface 9 on side B of the backing 10e is flat and flush with the side edges of the unreferenced alternating half slips and slips 14. Thus, on side B there is no side edge step portion 26, depressions 24, projections 25, notches 56 and narrow lip 40: only the top edge step portion 30 underiaps the backing 10 of an adjacent panel 12. The flat, flush, side enables the building panel 12e to be at the end of a wall surface where there is no need for inter-relationship with another building panel 12. The building paneis 12, 12a, 12b, 12c and 12d of Figs. 4 to 6 and 29, Figs. 14 and 30, Figs, 17 and 31, Figs. 20 and 32 and Figs. 23 and 32 respectively, and 12e of Fig. 26 together with the corner building panels 12f, 12g, 12h, 12i, 12j, 12k, 121, 12m, 12n and 120 of Figs. 34, 35, 36, 38, 39, 40, 41, 42 and 43 provide for most conceivable situations that normally occur in assembling walls to provide wall surfaces in buildings. Thus, the building panels of the invention are capable of immense variation whilst providing stability and water tightness by virtue of the underlapping backing step portions 26 and 30. A multiplicity of the building panels 12 and selected ones of the building panels 12a, 12b, 12¢, 12e, 12f, 12g, 12h, 12i, 12}, 12k, 12I, 12m, 12n and 120, as required to suit the particular situation, are assembled together and fixed as by suitable fixings (not shown) such as screws. The screws are screwed into the timber frame 50 of a building 51 (Fig. 44) through the four troughs 18 and ridges 17 of the backing 10 which are aligned conveniently with four of the joint gaps 13 respectively. Then, the joint gaps 13 between the slips 14 and between the adjacent panels 12, 12a etc. are filled with the same mortar to form the wall surfaces 52 (completed) and 54 and 56 (partially completed). All the building panels are fixed to the timber fame though a breather membrane 58, known as housewrap. In the front of the building 51 in Fig. 44, there are four piles of building panels, namely a pile 60 comprising building panels 12 (five slips 14 per course 16, Fig. 4), a pile 61 comprising building panels 12a (four slips 14 per course, Fig. 14), a pile 62 comprising corner building panels 12m (Fig. 41) and a pile 63 comprising corner building panels 12I (Fig. 40). Corner building panels 12} and 120 can be seen on opposite sides respectively of a proposed window 64 and corner building panel 12j beneath a proposed window 66. The underlapping continuous strip formed by the top and side edge step portions 30 and 26 stabilises the backings 10 and thus the panels 12 in the joint gaps 13 between the adjacent panels 12, guarding against relative movement between the adjacent assembled panels 12 in the joint gaps therebetween which would otherwise cause cracking of the mortar and ingress of water into the building 51 and its timber frame 50 through the cracks by capillary action. Moreover, the recesses 22 in the backing member 10 on side A and notches 56 in the side edge step portion 26 not only reduce the amount of plastics material used to form the backing 10 and thus the overall weight and cost of the building panels 12 but also facilitate handling of the building panels 12 without needing to use expensive equipment. This is because the panels 12 can be grasped easily on the opposite sides A and B by the two hands respectively of a builder and carried to, and positioned and fixed to, the timber frame 50 of the building 51. And the same applies to all the building panels 12a, 12b, 12c and 12d. The lighter corner building panels 12f, 12g, 12h, 12i, 12j, 12k, 12m and 12n can be similarly and easily manually handied. Although, the building panel 12e and the corner building panels 121 and120 do not have notches 56 at one side because they have a flat surface 9 formed by the sides of the slips being flush with the backing, these building panels are easy to handle manually because of their relatively small size and reduced weight compared to the panels 12 for example. The embodiment of Figures 45 to 50 differs from all the previous embodiments of building panel 12 in that, on side B, the backing 10a is devoid of notches 56 where the backing forms the depressions 24 to form a wider side edge step portion 26 that extends between the opposing sides of the slips 14 and peripheral lip 40.

Claims

Claims 1. A prefabricated building panel having oppositely facing side edges and top and bottom edges, a substantially rigid backing having front and rear surfaces, the backing being provided with a plurality of laterally extending reinforcing ridges projecting from its rear surface in parailel spaced apart relationship, a plurality of slips adhesively bonded to the front surface of the backing in a plurality of courses leaving joint gaps for the reception of mortar in same width spaces between the courses and the slips of each course, the backing also being provided with depressions which are formed by a step portion extending continuously beyond the slips along the top edge and along one of the side edges of the backing and providing a top edge step portion and a side edge step portion, and by rearward facing projections in the rear surface of the backing and lying in the same plane as that of the peaks of the ridges, the front surface of the backing having an area that is oversized compared to the area of the backing front surface covered by the bonded slips, leaving a narrow peripheral lip of the backing exposed immediately adjacent the slips and extending all the way around the bonded slips, the narrow lip having a width that is substantially one half that of the joint gaps between the slips, such that when a plurality of such building panels are assembled to form a wall surface, adjacent portions of the narrow lip along the top and bottom edges and oppositely facing side edges of adjacent building panels are brought into edge-to-edge abutment and the top edge step portion and side edge step portion respectively underlap the backings along the bottom edge and opposite side edge of two adjacent such building panels thereby to enable alignment of the front faces of the slips of adjacent assembled panels.

2. A prefabricated building panel as claimed in claim 1, wherein the backing has diametrically opposite top and bottom corner regions provided with cut- outs respectively to accommodate adjacent top and bottom edge portions respectively of the backing of adjacent assembled panels.

3. A prefabricated building panel as claimed in claim 1 or claim 2, wherein the laterally extending reinforcing ridges are in the form of corrugations whose peaks form the ridges that lie in a plane that is parallel to that of the rear surface of the backing and whose troughs open onto the front surface of the backing to which the slips are adhesively bonded.

4. A prefabricated building panel as claimed in claim 3, wherein the corrugations align with selected ones of the joint gaps between slip courses to facilitate ease of locating fixings.

5. A prefabricated building panel as claimed in any of claims 1 to 4, wherein the side step portion is provided with notches between the slips.

6. A prefabricated building panel as claimed in any of claims 1 to 5, wherein front surface of the backing has a scored grid of lines to facilitate accuracy of laying and bonding of the slips.

7. A prefabricated building panel as claimed in any of claims 1 to 6, wherein the backing is of substantially uniform thickness throughout and has sufficient rigidity to provide a dimensionally stable support.

8. A prefabricated building panel as claimed in claim 7, wherein the backing is of moulded glass-reinforced plastics.

9. A prefabricated building panel as claimed in any of claims 1 to 8, wherein the backing projects alternately to each side of the backing by substantially the length of one half slip to form a substantially vertical series of alternating laterally facing recesses and projections with the recesses and projections on one side being opposite the laterally facing projections and recesses respectively on the other side.

10. A prefabricated building panel substantially as hereinbefore described with reference to Figures 1, 1a, 2, 2a, 3,4,5,6, 7, 8, 8a, 8b, 9, 10, 10a, 11, 12, 13 and 29 of the accompanying drawings.

11. A prefabricated building panel substantially as hereinbefore described with reference to Figs. 14 to 16 and 30 of the accompanying drawings.

12. A prefabricated building panel substantially as hereinbefore described with reference to Figs. 17 to 19 and 31 of the accompanying drawings.

13. A prefabricated building panel substantially as hereinbefore described with reference to Figs. 20 to 22 and 32 of the accompanying drawings.

14. A prefabricated building panel substantially as hereinbefore described with reference to Figs. 23 to 25 and 33 of the accompanying drawings.

15. A prefabricated building panel substantially as hereinbefore described with reference to Figs. 26 to 28 of the accompanying drawings.

16. A prefabricated building panel substantially as hereinbefore described with reference to Fig. 34, Fig. 35, Fig. 36, Fig. 37, Fig. 38 or Fig. 39 of the accompanying drawings.

17. A prefabricated building panel substantially as hereinbefore described with reference to Fig. 40, Fig. 41, Fig. 42, or Fig. 43 of the accompanying drawings.

18. A prefabricated building panel substantially as hereinbefore described with reference to Figs 45 to 50 of the accompanying drawings.

19. A wall surface provided by a multiplicity of prefabricated building panels as claimed in any of claims 1 to 23.

20. A wall surface substantially as hereinbefore described with reference to Fig. 11 or Fig. 44 of the accompanying drawings.

21. A building incorporating a multiplicity of prefabricated building panels as claimed in any of claims 1 to 23 and providing at least one wall surface of that building.

22. A building incorporating a multiplicity of prefabricated building panels as claimed in any of claims 1 to 23 and providing at least one wall surface of that building and substantially as hereinbefore described with reference to Fig. 44 of the accompanying drawings.