GB2391024A

GB2391024A - Backing board for a prefabricated wall panel

Info

Publication number: GB2391024A
Application number: GB0216994A
Authority: GB
Inventors: John Fifield; Michael Ormesher
Original assignee: Forticrete Ltd
Current assignee: Forticrete Ltd
Priority date: 2002-07-22
Filing date: 2002-07-22
Publication date: 2004-01-28
Also published as: GB0216994D0

Abstract

A prefabricated wall panel has a plurality of slips 14 bonded to a backing board 10. The backing board is adapted to cooperate with the pointing 16 laid between the edges of the bricks, in such a way that the pointing is secured to the backing board by mechanical fixing, instead of just adhesive fixing, and thus the slips are more securely fixed. The backing board may comprise parallel strip members which may be continuous (36, Fig 7) or interrupted 22. These strip members serve to receive the pointing and also act as locating means to locate the slips on the backing boards. The interrupted strip members 22 may be provided with a dovetail shaped undercut opening 24 and also holes 34 in the backing board, to receive the pointing 16. The continuous strip (36, Fig 7) may also comprise holes (38, Fig 7) or alternatively a protruding looped wire (40, Fig 8) or staples (44, Fig 10).

Description

239 1 024

Improvements in or relating to boards for prefabricated wall nanelline systems The present invention relates to boards that are used as a backing and substrate-

retaining member in prefabricated wall panelling systems. More particularly, but not 5 exclusively, the substrates are decorative slips of concrete, brick, stone or other masonry materials.

Governmental support of prefabricated or 'factory-built' building components has led to the evolution and growing popularity of prefabricated wall panelling systems. These 10 wall panelling systems are based on affixing prefabricated sections of concrete, brick, or other masonry materials on to a backing board to form a wall panel. These sections of material tend to be decorative and thin and are commonly known in the trade as slips'. Pointing is applied in the spaces (joints) between the slips using mortar, for example, to act as a filler between the slips. The wall panels are installed on the 15 exterior or interior faces of buildings to function as the exterior facades of buildings or as interior wall panelling.

Wall panelling systems provide the durability and aesthetic characteristics of traditional brick or other decorative building materials whilst avoiding some of the 20 disadvantages associated with socalled traditional 'scratch-built' methods which involve brick-by-brick laying to form the building facade or interior panelling. With the prefabricated systems, components can be produced off-site and delivered to a building site exactly when needed, in the right order, and without defects. A higher quality of Amish on wall panels may be achieved for this reason and also due to the 25 feasibility of using higher quality (and more expensive) pre-cast slip products as less material is required. Also construction productivity is increased as the assembly of the slips to the backing board may be performed either in the factory ('off:site') or at the building site ('on-site') and is both faster than traditional methods and requires less labour. Assembled prefabricated wall panels are installed by simply hoisting them up 30 on the face of the building which offers a clear safety advantage over workers laying the walls at height.

Commonly, the slips are affixed to the board using a bonding agent, such as an

adhesive, for example glue, which forms a 'cross-hydration' chemical bond between the slip and the board. The slips may also be screwed into position on the backing board although this method has been largely superseded by the 'bonding' method. The backing board is made of plastics, metal, wood, or cement based composite materials.

In one known backing board, there are integral locating means in the form of strips for horizontally locating the slips on the backing board and which also prevent vertical slide' of the rows of slips on the installed wall panelling system. These strips form an array of parallel ribs defining tracks in which slips are arranged in courses, typically in 10 broken bond for brick slips. The wall panels are assembled by gluing the slips on the backing board while the backing board is horizontal, applying pointing in the gaps (joints) left between the slips and allowing the pointing to cure. The wall panelling system is then installed by positioning the assembled wall panels vertically adjacent to a wall.

Whilst the security of the slips affixed to the board largely depends upon the bonding agent used between the board and the slips, the pointing also contributes to the fixation of the slips to the backing board. Mechanical bonding is present between the pointing and the slips due to partial penetration of the pointing material into the slip 20 pores; the degree of mechanical bonding being dependent on the slip porosity. There is also frictional engagement of the slips and the pointing due to contact of their rough surfaces on oppositely facing sides. As will be appreciated, neither of these mechanical bonds is sufficient to prevent the entire face of the wall panelling system including the pointing detaching itself from the backing board if the bonding between 25 the slips and the board fails for any reason. In such a situation, especially with wall panelling systems mounted high up on a building, the consequences could be serious if not fatal.

Failure of the bonding between the slips and backing board has occurred in brick slips 30 affixed to a metal backing board which are secured by means of two strips of polymeric mastic, with the joints being filled with pointing mortar comprising sand and cement. In the event that water trapped between the slips and the metal backing freezes, it expands and exerts a pressure on the slips. In some cases, the pressure may

be enough to separate the slips entirely from the backing board. Several systems based on metal and plastics backing members all potentially suffer from this failure mechanism. 5 the applicant has found that the combination of materials used in prefabricated wall panels has a profound effect on the likelihood of bonding failure resulting in slips detaching from the backing board and falling from the installed wall. In this connection, the applicant's research has noted that with a suitable combination of materials, for example a cement based backing board and a cement based pointing 10 mortar, a degree of chemical bonding is achieved between the pointing and the backing board. However, the applicant found that even with this system, in extreme cases and in common with metal and plastics backing boards, there was a tendency for frozen water mapped between the slip and the board to exert pressure sufficient to dislodge both the slip and the pointing from the backing board. So although chemical 15 bonding between the backing board and pointing as a result of careful material selection can guard against the slips detaching from the backing board, it does not necessarily guarantee that the wall panel will remain intact in all instances. Even if the chance of failure is minimal, a failure in an extreme situation could still result in loss of life which is unacceptable.

Applicant has addressed this problem in GO 0108109.0 which discloses clipping means to secure the slips such that if the bond between the slips and the backing fails then the slips remain secured to the backing board by the clips. Although the clips work well with large masonry block slips, their use with brick sized slips would be 25 prohibitively expensive, impractical and commercially unacceptable as each slip would require clipping. In addition, this system requires that each slip be adapted to accommodate a clip which would add further expense.

Against this background, the present invention seeks to provide a backing board for a

30 prefabricated wall panelling system which avoids or minimises the disadvantages of the current prefabricated wall panelling systems as detailed above, at least in relation to brick-sized slips.

To this end, the present invention resides in a backing board for use as a prefabricated wall panel having a plurality of slips bonded to the backing board, characterised in that the backing board is adapted to co- operate with pointing laid between the slips to provide mechanical fixing between the slips and the backing board.

By means of the invention, mechanical clip means such as clips that secure the slips to the board are not necessary yet enhanced fixation of the slips to the backing board is ensured by virtue of the mechanical fixation of the pointing to the backing board.

10 Advantageously, the backing board is adapted to provide openings for receiving the pointing to fix mechanically the pointing to the backing board.

In a preferred embodiment, the slips are located to the backing board by means of an array of parallelly extending locating means defining tracks in which the slips are 15 arranged in courses, said locating means defining openings for receiving the pointing thereby to fix mechanically the pointing to the board.

In order to facilitate retention of the pointing by adaptation of the backing board, the openings can be of many different forms and shapes. For example, in one preferred 20 embodiment, the openings can be of dovetail shape for ease of manufacture. In other embodiments, the openings can be in the form of holes. Alternatively, the openings may be defined by a plurality of elements such as rows of staples or a series of open loops projecting from the locating means.

25 In order that the invention may be more readily understood, some embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of a backing board for a 30 prefabricated panel viewed from the upper surface, side edge and lower edge of' the board; Figure 2 is a perspective view of an assembled prefabricated panel showing the

backing board of Figure 1 with brick slips laid in position except for one unlaid row and without pointing in the joints between the slips; Figure 3 is cross-section of the assembled panel of Figure 2 taken along the line II-II; Figure 4 is a perspective view of an assembled prefabricated panel showing a backing board similar to that of Figure 1 with brick slips laid in position except for one unlaid row without pointing in the joints between the slips and parts of the board cut away for clarity of illustration; Figure 5 is a detail perspective view, to an enlarged scale, of one slip on a panel with pointing mortar applied to the joints between the slips, and parts of the applied pointing cut away and the backing board being partially shown in chain lines for clarity of illustration; Figure 6 is a perspective view from the upper surface, side edge and lower edge of a partially assembled panel showing another embodiment of backing board; Figure 7 is a perspective view from the upper surface, side edge and upper edge of a 20 partially assembled panel showing yet another embodiment of backing board; Figure 8 is a perspective view similar to that of Figure 7 showing a further embodiment of backing board; 25 Figure 9 is a perspective view similar to that of Figure 7 showing a still further embodiment of backing board; Figure lO is a perspective view similar to that of Figure 7 showing a yet still further embodiment of backing board.

Referring initially to Figures I, 2 and 5, there is provided a backing board to for use as a prefabricated wall panel 12 having a plurality of slips 14 bonded to the backing board 10. The backing board 10 is adapted to co-operate with pointing 16 (Figure 5)

laid between the slips 14 to provide mechanical fixing between the slips 14 and the backing board 10.

In Figure 1, to which more particular reference will now be made, there is shown a 5 backing board 10 of generally rectangular shape, made of a glass reinforced concrete (GRC). The upper surface 18 of the backing board 10 is provided with an array of parallely extending locating means 20 defining tracks in which brick slips 14 are arranged in courses, typically in broken bond as shown in Figure 2. The locating means are integral with the backing board 10 and are in the form of a plurality of 10 parallely extending interrupted solid strips 20 deeming openings 24 between individual strip members 22.

As can be seen more clearly in Figures l, 2, 4 and 5, the openings 24 are of dovetail shape such that the widest portion of the dovetail opening is contiguous with the upper 15 surface 18 of the backing board 10.

Each of the slips 14 positioned on the backing board 10, is in the form of a substantially solid cuboidal block defining six oblong faces. The slips 14 are moulded of any suitable material, such as clay as usual or concrete, which presents the desired 20 decorative finish on at least its exposed face. Specifically, the slip 14 has an upper surface 26, an undersurface 27 (visible in Figure 3), upper (not visible) edge wall, lower edge wall 28 and two side walls 30 (one of which is not visible). In use, the undersurface 27 of a slip 14 lies against and is bonded by a bonding agent to the upper surface 18 ofthe backing board 10.

Slips 14 are arranged on a backing board 10 and fixed in the located position between the strips 20 with suitable adhesive. The adhesive chemically bonds the undersurface 27 of the slip 14 to the upper surface 18 of the backing board 10. For ease of assembly, slips 14 are laid on the backing board 10 when the board 10 is in a 30 horizontal position. As can be seen in Figures 2 and 4, spaces (joints) 32 are left between adjacent slips 14 for aesthetic effect. Figure 4 shows a cross-sectional view of an assembled panel 12 showing the slips 14 laid on the backing board 10 and the strip members 22 locating the slips 14.

When all the slips 14 are in position on the backing board 1O7 pointing 16 is applied between the slips 14 so that the openings 24 between strip members 22 are completely filled, and the spaces 32 between the slips 14 are almost completely filled with 5 pointing 16 to emulate a traditionally built wall (Figure 5). When pointing 16 is applied to the openings 24 between the strip members 22, it keys into the undercut of the opening 24 and mechanically fixes the pointing 16 to the backing board 10 when the pointing 16 sets. Put another way, pointing 16 applied around and between the slips 14 fills the dovetail shaped openings 24 so that when the pointing 16 sets, the 10 pointing 16 is prevented mechanically from detaching from the backing board 10 by virtue of the undercuts of the dovetail shaped openings 24.

Figure 6 differs from Figures 1 to 5 in that an assembled wall panel 12a is shown comprising a backing board 1 Oa with holes 34 provided on the backing board upper 15 surface 18. The holes 34 are located between adjacent strip members 22 of the same row i.e. within the openings 24, and extend through the backing board 1 Oa. Pointing 16 (not shown) applied around the slips 14 is received in the openings 24 and penetrates the holes 34 thereby providing additional mechanical fixing between the pointing 16 and the backing board 10.

Figure 7 differs from Figures 1 to 5 in that a partially assembled wall panel 12b is shown comprising slips 14 positioned on a backing board 1 Ob having, instead of the dovetailed openings 24 of Figures 1 to 6, locating means in the form of an array of parallelly extending continuous strips 36, the strips 36 having holes 38 extending 25 through the strips 36 and into the backing board 1 Ob. The holes 38 may optionally be countersunk at the backing board 1 Ob undersurface (not shown). Alternatively, the holes 38 may extend through the strips lOb in a direction parallel to the upper surface 18 of the backing board 1 Ob instead of through the backing board 1 Ob (not shown).

30 Figures 8 to 10 differ from Figure 7 in that instead of holes 38 extending through the strips 36, rows of inserts of different shapes project from the strips 36.

In Figure X, the insert is in the form of wire which is threaded through the strips 36

and backing board lOc so that a series of open loops 40 protrude from the strips 36.

In Figures 9 and 10, staples 42, 44 are partially embedded in the strips 36 such that the two free ends of a staple are anchored in the strip 36 with the rest of the staple 5 protruding from the strip 36. In Figure 9, the staples 42 are an inverted 'v' shape and in Figure 10, the staples 44 are of a goal-post shape.

The present invention may be embodied in other specific forms without departing from its essential attributes as defined in the appended claims and other statements of

10 invention herein rather than the foregoing description as indicating the scope of the

invention. For example, the locating means, instead of being in the form of strips may be a plurality of pegs. Slips do not have to be cuboidal or laid in straight parallel courses.

15 They can be of any desired shape and can be disposed in any desired pattern, as may be dictated by the architectural design of the building for which the wall panel is intended. The slip need not necessarily be moulded, it can be a composite of a moulded substrate material faced with a decorative material after moulding. Instead of the openings along a strip being of dovetail shape, the openings may be constituted by 20 any other shape which has an undercut. Instead of the staples being mounted in the strips, they could be mounted directly on to the backing board in which case the staples would also serve as locating means.

Claims

1. A backing board for use as a prefabricated wall panel having a plurality of slips bonded to the backing board, characterised in that the backing board is adapted to co operate with pointing laid between the slips to provide mechanical fixing between the pointing and the backing board to enhance fixation of the slips to the backing board.

2. A backing board for use as a prefabricated wall panel having a plurality of slips bonded to the backing board, characterised in that the backing board is adapted to co-

operate with pointing laid between the slips to provide mechanical fixing between the slips and the backing board.

3. A backing board as claimed in claim I or claim 2, characterised in that the backing board is adapted to provide openings for receiving the pointing for fixing mechanically the pointing to the backing board.

4. A backing board as claimed in any one of claims I to 3, characterised in that the backing board is provided with locating means for locating the slips on the backing board.

5. A backing board as claimed in claim 4, characterised in that the locating means is in the form of an array defining tracks in which the slips are arranged in courses.

6. A backing board as claimed in claim 5, characterised in that the locating means is in the form of rows of parallely extending interrupted solid strip members.

7. A backing board as claimed in claim 6, characterised in that each interrupted solid strip member is a peg.

8. A backing board as claimed in claim 6 or claim 7, characterised in that the individual strip members of a row define the openings or opening for receiving the pointing.

9. A backing board as claimed in claim 8, characterised in that the pointing is received into the openings to fix mechanically the pointing to the backing board.

10. A backing board as claimed in claim 9, characterised in that the openings are undercut.

I 1. A backing board as claimed in claim 10, characterised in that the undercut shape of each opening is in the form of a dovetail.

12. A backing board as claimed in claim 1 1, characterised in that at least one hole is provided in the backing board in at least one of said openings.

13. A backing board as claimed in claim 12, characterised in that the hole or holes extends or extend through the backing board.

14. A backing board as claimed in claim 5, characterised in that the locating means is in the form of rows of parallely extending continuous strips.

15. A backing board as claimed in claim 14, characterised in that the openings are defined by at least one hole extending through the strip.

16. A backing board as claimed in claim I S. characterised in that the hole or holes extends or extend through the strip and the backing board.

17. A backing board as claimed in claim 16, characterised in that the openings are defined by inserts projecting from the strips.

18. A backing board as claimed in claim 17, characterised in that each insert is a wire threaded through the strips and backing board in the form of a series of open loops protruding from the strips defining the openings.

19. A backing board as claimed in claim 17, characterised in that each insert is a staple.

20. A backing board as claimed in claim 3 and any claim dependent on claim 3, characterised in that the locating means is integral with the backing board.

21. A backing board, substantially as hereinbefore described with reference to Figures I to 5 of the accompanying drawings.

22. A backing board, substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.

23. A backing board, substantially as hereinbefore described with reference to Figure 7 of the accompanying drawings.

24. A backing board, substantially as hereinbefore described with reference to Figure 8 of the accompanying drawings.

25. A backing board, substantially as hereinbefore described with reference to Figure 9 of the accompanying drawings.

26. A backing board, substantially as hereinbefore described with reference to Figure 10 of the accompanying drawings.