AU2006101045B4

AU2006101045B4 - A Backing Strip

Info

Publication number: AU2006101045B4
Application number: AU2006101045A
Authority: AU
Inventors: Stephen Charles Bean; Peter John Middleton
Original assignee: Peer Intellectual Properties Pty Ltd
Current assignee: Etex Australia Pty Ltd
Priority date: 2006-10-09
Filing date: 2006-12-12
Publication date: 2013-10-03
Anticipated expiration: 2014-10-09
Also published as: AU2006100887B4; AU2006101045A4; AU2006100887A4; NZ556037A

Abstract

Abstract A backing strip comprising a first portion adapted to be positioned behind at least one first cladding panel and a second portion adapted to be positioned behind at least one second cladding panel, and locating means adapted to engage against at least one of the cladding panels for correctly positioning the backing strip with respect to that at least one cladding panel.

Description

Il A BACKING STRIP FIELD OF THE INVENTION The present invention relates to an improved backing strip that may find particular use 5 in constructing wall cladding for buildings and other like structures. BACKGROUND The facades of buildings and like structures are often formed from a number of cladding panels (also referred to as cladding "sheets" or cladding "boards"). The 10 panels are generally flat and rectangular, and they are typically approximately 500mm - 2500mm in height, 1500mm - 3000mm in width and 9mm - 25mm in thickness. However, it will be appreciated that cladding panels of a wide range of other sizes can also be used. 15 Cladding panels can be constructed from a variety of materials and using a range of manufacturing techniques depending on the intended application and the environment to which the cladding is likely to be exposed. As an example, cladding panels which comprise sheets of plasterboard or compressed fibre cement, and which are sealed on both the internal and external faces of the panel to prevent water penetration and 20 increase the panels' wind loading capacity, are particularly favoured. Figure 1 illustrates one of the prior art ways that cladding panels can be installed. From Figure 1, it can be seen that the facade is formed by the exterior surfaces of a number of cladding panels. The cladding panels (shown in Figure 1 by reference 25 numerals 9, 1Oa, lOb, I Ia and 11 b respectively) are depicted in a partially cut-away view so that the components used to mount the panels to the supporting structure of the wall can be seen (the supporting structure of the wall is not shown). The components used to mount the panels to the supporting structure in the configuration of Figure 1 include channel-like "top hats" 12, "backing strips" 14 and gaskets 16. 30 When installing the cladding panels, the top hats 12 are first attached to the supporting structure of the wall (not shown) in the substantially vertical orientation illustrated in Figure 1. The part of the supporting structure of the wall to which the top hats attach depends on the particular structure of the wall. For example, in buildings which have 2 a wooden or steel frame construction, the top hats may be secured to the studs or battens of the frame. Alternatively, in buildings in which the walls are constructed from bricks or concrete blocks, the top hats may be secured directly to the surface of the brick/concrete wall. The top hats are typically attached to the supporting structure 5 of the wall using mechanical fasteners suitable for use with the particular wall construction, for example bolts or screws (not shown). In the configuration shown in Figure 1, each top hat 12 has a generally channel-like cross-section comprising a pair of outwardly projecting wings 18, a pair of flanges 19 10 which form the walls of the channel, and a web 20 extending between the walls. Each top hat 12 is installed so that the open side of the channel faces inwardly towards the supporting structure of the wall, and each one is secured to the supporting structure by inserting suitable mechanical fasteners (not shown) through the wings 18 and into the supporting structure. In this configuration, the cladding panels are then secured to the 15 web 20 using mechanical fasteners (not shown) as described below. Hence, the depth of the flanges 19 in the direction perpendicular to the plane of the cladding panels defines the depth of the wall cavity between the supporting structure of the wall and the internal surface of the cladding panels. Alternative top hats to the ones shown in Figure 1 can also be used. For example, some top hats may be installed with the 20 channel opening outwardly from the supporting structure of the wall so that the web of the top hat attaches to the supporting structure and the cladding panels attach to the wings. The configuration in Figure 1 also incorporates additional "intermediate" top hats 22 25 which are positioned as shown. The purpose of the intermediate top hats 22 is described below. As shown in Figure 1, the top hats 12 are attached to the supporting structure parallel to each other and at evenly spaced apart locations. This enables the vertical edges of 30 horizontally adjacent cladding panels to be secured to the top hats. For example, the right-hand vertical edge of cladding panel 9 and the left-hand vertical edge of horizontally adjacent cladding panel 10a both attach to the top hat 12 shown on the left in Figure 1. Likewise, the right-hand vertical edge of cladding panel 10a and the left-hand vertical edge of cladding panel Ia attach to the top hat 12 shown on the 3 right. The same applies for the next row of cladding panels above, and for the panels extending further left and right. Hence, the pattern can be repeated to create a facade for the entire area of wall to be clad. 5 The intermediate top hats 22 are positioned at spaced apart locations, with one or more intermediate top hats positioned between each pair of top hats 12 (only one intermediate top hat 22 is shown between the top hats 12 in Figure 1). The intermediate top hats 22 therefore attach to the cladding panels between the panels' vertical side edges in order to provide additional support in bearing the weight of the 10 panels and to help resist other forces such as wind loading, thermal expansion and the like. The cladding panels attach to the top hats 12 and the intermediate top hats 22 by way of mechanical fasteners (not shown). It can also be seen that the top hats 12 typically have gaskets 16 extending vertically 15 down the middle of their respective webs 20. When the cladding panels are attached to the top hats 12 as shown, the gasket 16 becomes squashed between the vertical side edges of the cladding panels and the web 20 of the top hats. Thus, the purpose of gaskets 16 is to provide a seal between the vertical side edges of the cladding panels and the top hats in order to prevent ingress of water, dust and the like into the wall 20 cavity. The prior art cladding system of Figure 1 also includes backing strips 14. One of the purposes of the backing strips 14 is to help in correctly positioning vertically adjacent cladding panels with respect to one another. Backing strips such as the ones shown in 25 Figure 1 comprise a substantially flat strip of thin metal with a small rounded ridge 24 extending along its length. Figures 2a and 2b show respective front and rear views of the backing strips used in Figure 1. Figure 1 shows that the backing strips 14 can be positioned behind vertically adjacent 30 cladding panels so that the width of the backing strip spans the space between the upper horizontal edge of the lower panel(s) and the lower horizontal edge of the upper panel(s). For example, in Figure 1 a backing strip 14 is positioned behind vertically adjacent panels 10a and 10b so as to overlap behind the upper horizontal edge of panel 10a and behind the lower horizontal edge of panel 10b, thus spaning the space 4 therebetween. Likewise, a backing strip is positioned behind panels 1 la and 1 lb in a similar manner. In the configuration shown in Figure 1, at least the portion of each backing strip which is visible between the panels can be coloured black or some other suitable colour for aesthetic purposes (for example, to provide the appearance of a 5 border around each panel). When the backing strips are positioned behind respective vertically adjacent cladding panels as described above, the small rounded ridge 24 on the backing strip protrudes into the space between the panels. This is intended to provide a guide for correctly 10 vertically positioning the panels with respect to one another. However, the ridge 24 generally does not occupy all of the space between the panels, and lines of sealant 26 (for example a settable liquid silicon-based type sealant) are therefore applied between the ridge 24 and the upper and lower edge(s) of the respective lower and upper panel(s). This is intended to further assist in preventing ingress of water and 15 dust etc into the wall cavity. The way that sealant 26 is applied between the ridge 24 and the horizontal edges of the upper and lower panel(s) is shown in Figure 4 wherein the sealant is shown in grey. There are a number of problems with backing strips such as those described above. 20 One particular problem arises because such backing strips are commonly formed as long thin metal strips (often up to several metres in length). Because of their thin metal construction, the long strips can be extremely flexible or "floppy" as shown in Figure 3. This flexibility tends to make them difficult to handle on site, particularly as the cladding strips are often formed in long lengths, and it also makes them difficult to 25 precisely position behind the cladding panels as required when installing the cladding. Another difficulty arises because the size and shape of the small rounded ridge 24 can be inadequate to prevent the backing strip from sliding behind the cladding panels before the backing strip can be secured in position. Furthermore, the size and shape of the small rounded ridge 24 can also be inadequate to stop the cladding panels from 30 sliding over on top of the ridge before the cladding panels can be secured in position on the top hats. This reduces the effectiveness of the backing strip in helping to correctly vertically position the panels with respect to the backing strip and one another.

5 It will be clearly appreciated that any reference herein to background material or a prior publication is for the purpose of assisting in understanding the invention only and is not to be taken as an acknowledgement or admission that any background material, publication or combination thereof formed part of the common general 5 knowledge in the field, or is otherwise admissible prior art, whether in Australia or in any other country. DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a backing strip which may at least 10 partially ameliorate one or more of the above-mentioned disadvantages, or which may provide a useful or commercial choice. Therefore, in a first broad aspect the present invention resides in a backing strip comprising a first portion adapted to be positioned behind at least one first cladding 15 panel and a second portion adapted to be positioned behind at least one second cladding panel, and locating means adapted to engage against at least one of the cladding panels for correctly positioning the backing strip with respect to that at least one cladding panel. 20 It is envisaged that the backing strip will typically have an overall flat elongate shape, similar in general terms to the backing strips described in the background section above. In particular, the first and second portions may be substantially flat, thin and coplanar with each other along the length of the backing strip to help enable the first and second portions to fit snugly in behind the respective first and second cladding 25 panel(s). By providing locating means adapted to engage against at least one of the cladding panels, the backing strip of the present invention may help to overcome difficulties associated with correctly positioning the cladding panels with respect to one another. 30 In particular, the locating means may help to prevent the backing strip from sliding behind the cladding panels before the backing strip can be secured in position, and also help to stop the cladding panels from riding over on top of the backing strip before the panels are secured in position and as they are being secured in position.

6 Preferred embodiments of the backing strip in accordance with the invention may be adapted for use between vertically adjacent cladding panels such as panels having the substantially rectangular flat shape described in the background section above, or multiple sets of such vertically adjacent cladding panels. However, no particular 5 limitation is meant thereby and other embodiments may be adapted for use between horizontally or even diagonally adjacent cladding panels, or between panels having alternate non-rectangular or curved shapes. In preferred embodiments adapted for use between vertically adjacent cladding 10 panels, the first portion of the backing strip may comprise an upper planar portion adapted to be positioned behind one or more upper panels. Likewise, the second portion may comprise a lower planar portion (preferably substantially coplanar with the first portion) adapted to be positioned behind one or more lower panels. Also, in these preferred embodiments the locating means may form part of the backing strip, 15 preferably positioned between the top and bottom of the backing strip, with at least a portion of the locating means being configured to abut with one or more of cladding panels. Preferably, at least a portion of the locating means may be configured to abut with an upper edge (typically, but not necessarily a substantially straight horizontal upper edge) of the one or more lower cladding panels. This portion may be referred 20 to as a lower abutting portion of the locating means. Even more preferably, the lower abutting portion may extend outwardly at least some way over the top of the upper edge of the lower panel(s), and the outwardly extending lower abutting portion may engage against the upper edge of the panel(s). In these embodiments, the outwardly extending lower abutting portion may engage against the upper edge of the panel(s) 25 by physically sitting on top of, and resting against the upper edge, thereby helping to maintain the backing strip in position with respect to the lower panel(s). The lower abutting portion may contact directly with the upper edge of the lower panels. Alternatively, some kind of sealing means may be provided between the lower 30 abutting portion and the upper edge to prevent ingress of water, dust and the like therebetween. The sealing means may take any suitable (preferably thin) form, for example a gasket or an applied settable liquid sealant etc. Even in embodiments which use sealing means between the lower abutting portion and the upper edge of the lower panel(s), the lower abutting portion may still engage against the upper edge of 7 the panel(s) by sitting on top of, and resting against the sealing means, with the sealing means then directly contacting with the upper edge of the panel(s), such that the lower abutting portion (and hence the backing strip) is still at least partially supported on the upper edge of the lower panel(s). Therefore, as the person skilled in 5 the art will appreciate, even when sealing means are used between the lower abutting portion and the upper edge of the lower panel(s), the abutting portion may still effectively sit on top of, and rest against the upper edge of the lower panel(s). Preferably, a portion of the locating means may also be configured to abut with a 10 lower edge (typically, but not necessarily a substantially straight horizontal lower edge) of the one or more upper cladding panels. This portion may be referred to as an upper abutting portion of the locating means. Even more preferably, the upper abutting portion may extend outwardly at least some way beneath the bottom of the lower edge of the upper panel(s), and the lower edge of the panel(s) may engage 15 against the outwardly extending upper abutting portion. In these embodiments, the lower edge of the panel(s) may engage against the outwardly extending upper abutting portion by physically sitting on top of, and resting against the upper abutting portion, thereby helping to maintain the panel(s) in position with respect to the backing strip. 20 As for the lower abutting portion, the upper abutting portion may contact directly with the lower edge of the upper panel(s). Alternatively, some kind of sealing means may be provided between the upper abutting portion and the lower edge of the panel(s), and the sealing means may take any suitable form. Also, as for the lower abutting portion, in embodiments which use sealing means between the upper abutting portion 25 and the lower edge of the upper panel(s), the lower edge of the panel(s) may still engage against the upper abutting portion by sitting on top of, and resting against the sealing means, with the sealing means then directly contacting with the upper abutting portion, such that the upper panel(s) is/are still at least partially supported on the upper abutting portion. Therefore, as the person skilled in the art will appreciate, even 30 when sealing means are used between the lower edge of the upper panel(s) and the upper abutting portion, the lower edge of the upper panel(s) may still effectively sit on top of, and rest against the upper abutting portion.

8 In preferred embodiments of the invention the backing strip may also include a portion located between the cladding panels in use which is adapted to shed water. This may help to further reduce the likelihood of water penetrating between the backing strip and (a) cladding sheet(s) and into the wall cavity. The water shedding 5 portion will preferably slope generally downwardly and outwardly. Preferably, the slope of the water shedding portion may be sufficient to cause water to run off the water shedding portion of the backing strip and down the external surface of the cladding, rather than penetrating the space between the cladding panels and the backing strip to run down inside the wall cavity. 10 In particularly preferred embodiments of the invention, the water shedding portion will form part of the locating means. Even more preferably, the water shedding portion will be configured in a manner whereby it extends between the outermost points on the outwardly upper and lower projecting abutting portions. Furthermore, 15 the inward end of the upper abutting portion may connect to the bottom of the planar first portion of the backing strip, and the lower abutting portion may connect at its inward end to the upper edge of the backing strip's second portion. Hence, the backing strip of the present invention may preferably comprise a single piece. Even more preferably, the backing strip may be formed as a single unitary component. The 20 person skilled in the art will appreciate that this may significantly reduce the complexities involved in the production of the backing strip. When preferred embodiments of the present backing strip are used, the lower abutting portion of the locating means may engage against the upper edge(s) of the lower 25 cladding panel(s) so as to correctly position the backing strip with respect to the lower cladding panel(s), and the lower edge(s) of the upper cladding panel(s) may abut with and rest on top of the upper abutting portion to correctly position the upper cladding panel(s). Thus, the present invention may provide significant advantages for correctly positioning vertically adjacent cladding panels. 30 As explained above, in particularly preferred embodiments, the backing strip may be integrally formed as a single unitary component. It is envisaged that backing strips in accordance with these embodiments will typically be made from strips of thin metal sheet (preferably between 0.5mm - 5mm in thickness), with each strip being folded 9 (perhaps multiple times) along its length to form the outwardly extending abutting portions and the sloped water shedding portion extending therebetween. However, alternative materials and/or construction methods may also be used. For example, plastics which are initially moulded with the correct shape may be suitable, as may 5 plastics which are initially moulded in thin flat sheets and re-shaped later using suitable techniques to form the locating means. In the embodiments described in the previous paragraph, further advantages may arise because of the size and shape of the outwardly extending abutting portions and the 10 sloped water shedding portion (which collectively form the locating means in these embodiments). In particular, the size of the outwardly extending abutting portions and the sloped water shedding portion, and the amount of material in those portions, may be substantially greater than that in the small rounded ridge in the backing strips described in the background section above. This, combined with the way that the 15 material in the abutting portions and the water shedding portion is displaced away from the plane of the backing strip's first and second planar portions, may give the backing strip a substantially greater second moment of area with respect to the said plane than the backing strips described in the background section. This greater second moment of area may help to increase the rigidity of the backing strip, and 20 hence its resistance to bending in the direction perpendicular to the plane of the first and second portions. In other words, the increased second moment of area may reduce the backing strip's flexibility or "floppiness". This may make the present backing strip easier to handle on site, particularly where the backing strips comprise long strips (perhaps up to several metres in length). 25 In another broad aspect, the present invention resides in a backing strip comprising a first planar portion adapted to be positioned behind at least one relatively upper cladding panel, a second planar portion adapted to be positioned behind at least one relatively lower cladding panel, the second portion being substantially coplanar with 30 the first portion but positioned relatively downwardly thereof, an upper engaging portion adapted to engage with at least part of a lower edge of at least one relatively upper cladding panel, a lower engaging portion adapted to engage with at least part of an upper edge of at least one relatively lower cladding panel, and a water shedding 10 portion between the upper and lower engaging portions and sloping downwardly and outwardly with respect to the plane of the first portion. Preferably, the upper and/or the lower engaging portions may extend outwardly 5 substantially perpendicularly to the plane of the first and second portions. Also, the water shedding portion may extend between the outer ends of the respective upper and lower engaging portions. Backing strips having features of shape and configuration described with reference to 10 the second broad aspect of the invention provide benefits in terms of rigidity, water shedding ability, and the ease with which vertically adjacent cladding panels can be correctly aligned during installation. In particular, because the water shedding portion slopes downwardly and outwardly with respect to the plane of the first and second portions, and because the engaging portion extends outwards substantially 15 perpendicularly to that plane, the material in those portions is positioned away from the plane. This gives the backing strip an increased second moment of area (and hence increased rigidity about the plane of the first and second portions). The downward and outward slope of the water shedding portion also helps to cause water to run off the water shedding portion rather than penetrating between the cladding 20 panels and the backing strip and into the wall cavity behind the panels. Furthermore, the way in which the engaging portions are each adapted to engage with at least a part of the respective upper and lower edges of at least one of the respective relatively lower and upper cladding panels helps to correctly align the backing strip and the cladding panel(s), thereby increasing the ease with which the panels can be correctly 25 positioned during installation. BRIEF DESCRIPTION OF THE DRAWINGS Certain background information is provided in the section entitled "background" above. That background information is provided solely for the purpose of assisting in 30 understanding the invention and it makes reference to the earlier drawings in which: Figure 1 illustrates one way that cladding panels are currently installed, and the role of the existing backing strips in this configuration; 11 Figures 2a and 2b show respective front and rear views of the existing backing strip used in Figure 1; Figure 3 illustrates the flexibility or "floppiness" of the existing backing strips in Figures 1, 2a and 2b; and 5 Figure 4 shows the way that sealant is applied to both sides of the ridge of existing backing strips. One particularly preferred (but non-limiting) embodiment of a backing strip in accordance with the present invention is described below with reference to the latter 10 drawings in which: Figures 5 shows a cross-sectional view of a backing strip in accordance with the embodiment of the invention presently described; Figure 6 shows the positioning of the presently described backing strip in 15 relation to respective upper and lower cladding panels; and Figure 7 illustrates one way that the presently described backing strip can be used in the installation of cladding panels. DETAILED DESCRIPTION OF THE LATTER DRAWINGS 20 In Figure 5-7 a backing strip in accordance with the presently described embodiment of the invention is shown and generally indicated by reference numeral 140. Referring first to Figure 5 it can be seen that backing strip 140 comprises a first substantially planar upper portion 142 and a second substantially planar lower portion 25 144. The lower portion 144 is substantially coplanar with the upper portion 142. Integrally formed between the upper and lower portions is locating means 146. Locating means 146 is made up of three parts which together form a noes-like shape when viewed in cross-section as shown in Figure 5. The first part is an upper abutting portion 147 which extends perpendicularly outwardly from the bottom edge of upper 30 portion 142. The second part is a water shedding portion 148 which extends with a substantially downward and outward slope away from the outer edge of upper abutting portion 147. The third part of the nose shaped locating means 146 is a lower abutting portion 150 which extends outwardly substantially perpendicular to the coplanar upper and lower portions 142, 144. The bottom end of the downwardly 12 sloping water shedding portion 148 connects to the outer edge of lower abutting portion 150. The cross-section of backing strip 140 as shown in Figure 5 remains substantially constant along the length of the backing strip. 5 A comparison of Figure 5 with Figures 2a and 2b clearly shows that the size of the nose shaped locating means 146 in the embodiment of the present backing strip is considerably larger than the size of the small rounded ridge 24 in the existing backing strips. The amount of material contained in the locating means 146, and the location of that material away from the plane of the upper and lower portions 142 and 144 10 results in the present backing strip being considerably stiffer than existing backing strips. Figure 6 illustrates the way in which the backing strip 140 can be positioned in relation to the respective lower and upper cladding panels I 00a and I 00b. Firstly, it 15 can be seen that, upon installation, the first upper portion 142 is positioned behind the lower edge of upper panel 100b, and that the second lower portion 144 is positioned behind the upper edge of lower panel 100a. It can also be seen that the outwardly extending lower abutting portion 150 extends out over the upper edge of lower cladding panel 100a and rests thereon so as to at least partially support the backing 20 strip on that upper edge. This may help to accurately position the backing strip with respect to the lower cladding panel 100a. In some cases a thin line of sealant (not shown) may be inserted between the underside of abutting portion 150 and the upper edge of panel 100a to prevent water from penetrating through the space in between and into the wall cavity. 25 It can also be seen from Figure 6 that the upper cladding panel 100b is positioned with its lower edge resting on top of upper abutting portion 147 so as to help accurately position the upper cladding panels with respect to the backing strip. A line of sealant may also be inserted between the bottom edge of panel 100b and the upper face of 30 upper abutting portion 147 to prevent penetration of water therethrough. Furthermore, from Figure 6 it can be seen that, due to the slope of water shedding portion 148, any water droplets that come into contact therewith (e.g. rain that blows in, or water running down of the outside surface of the upper panel 100b) will simply 13 run off and down the outside face of the lower panel 100a, rather than penetrating through into the wall cavity. The same may apply for dust and the like. Finally, Figure 7 illustrates one way that the embodiment of the backing strip 5 presently described can be used in the installation of cladding panels. Apart from the differences between the present backing strip 140 and existing backing strips 14 described above and the benefits that these differences provide, the manner in which the cladding is installed with the present backing strip is generally the same as when existing backing strips are used. 10 It will be clearly appreciated the various changes and modifications may be made to the particular embodiment described without departing from the spirit and scope of the present invention.

Claims

1. A backing strip comprising a first planar portion adapted to be positioned behind at least one relatively upper cladding panel, a second planar portion adapted to be positioned behind at least one relatively lower cladding panel, the second portion being substantially coplanar with the first portion but positioned relatively downwardly thereof, an upper engaging portion adapted to engage with at least part of a lower edge of at least one relatively upper cladding panel, a lower engaging portion adapted to engage with at least part of an upper edge of at least one relatively lower cladding panel, and a water shedding portion between the upper and lower engaging portions and sloping downwardly and outwardly with respect to the plane of the first portion.

2. A backing strip as claimed in claim 1, wherein the slope of the water shedding portion is sufficient to cause water to run off the water shedding portion and down the external surface of the cladding panels.

3. A backing strip as claimed in claim 1 or claim 2, wherein the upper engaging portion extends, substantially perpendicular to the first planar portion, from the bottom of the first planar portion to the top of the water shedding portion, and the lower engaging portion extends, substantially perpendicular to the second planar portion, from the top of the second planar portion to the bottom of the water shedding portion.

4. A backing strip as claimed in any one of claims 1-3, wherein the lower engaging portion helps to prevent the backing strip from sliding behind the at least one relatively lower cladding panels before the backing strip is secured in position, and the upper engaging portion helps to stop the at least one relatively upper cladding panels from riding over the top of the backing strip before said panels are secured in position.

5. A backing strip as claimed in any one of the preceding claims formed as a single unitary component from folded metal of thickness less than 5 mm.