AU2006100887A4

AU2006100887A4 - A Backing Strip

Info

Publication number: AU2006100887A4
Application number: AU2006100887A
Authority: AU
Inventors: Stephen Charles Bean
Original assignee: METAL BUILDING SYSTEMS HOLDING
Current assignee: Etex Australia Pty Ltd
Priority date: 2006-10-09
Filing date: 2006-10-09
Publication date: 2006-11-23
Anticipated expiration: 2014-10-09
Also published as: AU2006100887B4; AU2006101045A4; NZ556037A; AU2006101045B4

Description

A BACKING STRIP SFIELD OF THE INVENTION

C.)

0 The present invention relates to an improved backing strip that may find particular use in constructing wall cladding for buildings and other like structures.

BACKGROUND

00 00 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.

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 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 numerals 9, 1Oa, 10b, 1 la and 1 lb 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.

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 INO 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 O the brick/concrete wall. The top hats are typically attached to the supporting structure of the wall using mechanical fasteners suitable for use with the particular wall construction, for example bolts or screws (not shown).

00oO 00oO 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 O 10 which form the walls of the channel, and a web 20 extending between the walls. Each Stop 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 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 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 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 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 1 la attach to the top hat 12 shown on the IND right. The same applies for the next row of cladding panels above, and for the panels

C

Cextending further left and right. Hence, the pattern can be repeated to create a facade Sfor the entire area of wall to be clad.

C.)

O

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 The 00 00 intermediate top hats 22 therefore attach to the cladding panels between the panels' Svertical 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 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 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 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 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 IN therebetween. Likewise, a backing strip is positioned behind panels 11 a and 1 lb in a

O

Osimilar 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 O suitable colour for aesthetic purposes (for example, to provide the appearance of a border around each panel).

r- When the backing strips are positioned behind respective vertically adjacent cladding 00 00 panels as described above, the small rounded ridge 24 on the backing strip protrudes

O

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 may not always occupy all of the space between the panels, and lines of sealant 26 (for example a settable liquid silicon-based type sealant) are 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 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.

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 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 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 one another. The complexity of the cladding installation process is further increased with these kinds of backing strips because it is necessary to apply the sealant 26 on either side of the ridge 24 to seal the N gaps between the backing strip and the respective panels. Without the sealant, the

O

Oshape of the ridge 24 could allow water to penetrate between the panels and the backing strip and into the wall cavity.

O

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 Sand is not to be taken as an acknowledgement or admission that any background 00 OO material, publication or combination thereof formed part of the common general

O

_knowledge in the field, or is otherwise admissible prior art, whether in Australia or in S 10 any other country.

O

DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a backing strip which may at least 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 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 the said at least one cladding panel.

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 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.

In particular, the locating means may help to prevent the backing strip from sliding I behind the cladding panels before the backing strip can be secured in position, and 0 Oalso help to stop the cladding panels from riding over on top of the backing strip before the panels are secured in position.

C.)

0 S 5 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 00 0O multiple sets of such vertically adjacent cladding panels. However, no particular Slimitation is meant thereby and other embodiments may be adapted for use between S 10 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 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, 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 the lower 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 horizontal upper edge) of the one or more lower cladding panels. Even more preferably, the 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 abutting portion may engage against the upper edge of the panel(s). In these embodiments, the extending portion may engage against the upper edge of the panel(s) 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 abutting portion may contact directly with the upper edge of the lower panels.

Alternatively, some kind of sealing means may be provided between the 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 IND or an applied settable liquid sealant etc. Even in embodiments which use sealing

O

Omeans between the abutting portion and the upper edge of the lower panel(s), the abutting portion may still engage against the upper edge of the panel(s) by sitting on O top of, and resting against the sealing means, with the sealing means then directly S 5 contacting with the upper edge of the panel(s), such that the abutting portion (and hence the backing strip) is still at least partially supported on the upper edge of the Slower panel(s). Therefore, as the person skilled in the art will appreciate, even when 00 00 sealing means are used between the abutting portion and the upper edge of the lower

O

panel(s), the abutting portion may still effectively sit on top of, and rest against the 10 upper edge.

O

Whilst some embodiments of the invention may operate with sealing means between the abutting portion and the upper edge of the lower cladding panel(s), in preferred embodiments of the invention the locating means may also include a portion adapted to shed water. This may help to eliminate or at least reduce the need to apply a second line of sealant between the backing strip and the lower edge of the upper cladding panel(s). The water shedding 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.

In particularly preferred embodiments of the invention, the water shedding portion and the abutting portion of the locating means will both be connected to each other, preferably in a manner whereby the lower end of the sloped water shedding portion connects at or near the outermost point on the outwardly projecting abutting portion.

Furthermore, the upper end of the sloped water shedding portion may connect to the bottom of the planar first portion of the backing strip, and the 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 person skilled in the art will appreciate that this may significantly reduce the complexities involved in the production of the backing strip.

IND The connection between the upper end of the sloped water shedding portion and the

O

O bottom of the planar first portion may also provide advantages in relation to the positioning of the upper cladding panel(s). In particular, if there is a noticeable O delineation between the first portion and the sloped water shedding portion, e.g. a fold line, ridge or some other such feature, then the line or other feature may be used as a means for correctly aligning the lower edge of the upper panel(s) with respect to the r backing strip. Hence, with preferred embodiments of the present backing strip, the 00 00 abutting portion of the locating means may engage against the upper edge(s) of the

O

lower cladding panel(s) so as to correctly position the backing strip with respect to the 10 lower cladding panel(s), and the lower edge(s) of the upper cladding panel(s) may then be aligned with the delineation between the first portion and the sloped water shedding portion to correctly position the upper cladding panel(s). Thus, the present invention may provide significant advantages for correctly positioning vertically adjacent cladding panels.

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 (perhaps multiple times) along its length to form the outwardly extending abutting portion and the sloped water shedding portion. 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 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 portion and the sloped water shedding portion (which together form the locating means in these embodiments). In particular, the size of the outwardly extending abutting portion and the sloped water shedding portion, and the amount of material in those portions, may be substantially greater than that of the small rounded ridge in the backing strips described in the background section above. This, combined with the way that the material in the abutting portion and the water shedding portion is displaced away from N the plane of the backing strip's first and second planar portions, may give the backing

O

Ostrip 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 O of area may help to increase the rigidity of the backing strip, and 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 00 00 on site, particularly where the backing strips comprise long strips (perhaps up to

O

Oseveral metres in length).

,C

O

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 water shedding portion extending below the first portion and sloping downwardly and outwardly with respect to the plane of the first portion, 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, and an engaging portion extending outwardly substantially perpendicularly to the plane of the first and second portions adapted to engage with at least a part of an upper edge of the at least one relatively lower cladding panel, the engaging portion extending between the top of the second portion and the bottom of the water shedding portion.

Backing strips having features of shape and configuration described with reference to the second broad aspects 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 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 panels and the backing strip and into the wall cavity behind the panels. Furthermore, IDthe way in which the engaging portion is adapted to engage with at least a part of the Supper edge of the at least one relatively lower cladding panels helps to correctly align Sthe backing strip with respect to the said relatively lower cladding panel(s), thereby O increasing the ease with which the panels can be correctly aligned during installation.

BRIEF DESCRIPTION OF THE DRAWINGS Certain background information is provided in the section entitled "background" 00 oO 00oO above. That background information is provided solely for the purpose of assisting in Sunderstanding the invention and it makes reference to the earlier drawings in which: S Figure 1 illustrates one way that cladding panels are currently installed, and the role of the existing backing strips in this configuration; 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 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 drawings in which: Figures 5a, 5b and 5c show respective front, rear and cross-sectional views of a backing strip in accordance with the embodiment of the invention presently described; Figure 6 illustrates the rigidity of the backing strip in Figures 5a, 5b, and Figure 7 shows the positioning of the presently described backing strip in relation to respective upper and lower cladding panels; and Figure 8 illustrates one way that the presently described backing strip can be used in the installation of cladding panels.

DETAILED DESCRIPTION OF THE LATTER DRAWINGS INO In Figures 5a, 5b, 5c, 6, 7 and 8 a backing strip in accordance with the presently 0 described embodiment of the invention is shown and generally indicated by reference numeral 140.

C.)

O

Referring first to Figures 5a, 5b and 5c it can be seen that backing strip 140 comprises a first substantially planar upper portion 142 and a second substantially planar lower rportion 144. The lower portion 144 is substantially coplanar with the upper portion 00 00 142. Integrally formed between the upper and lower portions is locating means 146.

Locating means 146 is made up of two parts which together form a shape resembling a human nose when viewed in cross-section as shown in Figure Sc. The first part is a water shedding portion 148 which extends with a substantially downward and outward slope away from the bottom of upper portion 142 (hence the downwardly sloping water shedding portion 148 resembles the bridge of a human nose). The second part of the nose shaped locating means 146 is an abutting portion 150 which extends outwardly substantially perpendicular to the coplanar upper and lower portions (hence the abutting portion 150 resembles the underside of a human nose).

The downwardly sloping water shedding portion 148 and the outwardly extending abutting portion 150 join together at their respective outer ends (ie to form the tip of the nose). As can be seen from Figures 5a and 5b, the cross-section of backing strip 140 as shown in Figure 5c remains substantially constant along the length of the backing strip.

A comparison of Figures 5a, 5b and 5c 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 results in the present backing strip being considerably stiffer than existing backing strips. This is clearly shown by comparing Figure 6 with Figure 3.

Figure 7 illustrates the way in which the backing strip 140 can be positioned in relation to the respective lower and upper cladding panels 100a and 100b. Firstly, it can be seen that 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 IND upper edge of lower panel 100a. It can also be seen that the outwardly extending 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 strip on that upper O edge. This may help to accurately position the backing strip with respect to the lower cladding panel 1 00a. 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.

00 00 SIt can also be seen from Figure 7 that the upper cladding panel 1 00b is positioned with 10 its lower edge generally aligned with the fold line 152 where the bottom of upper Splanar portion 142 meets with the top of the downwardly sloping water shedding portion 148. Aligning the lower edge of the upper panel 100b with fold line 152 may help to correctly position the upper panel with respect to the backing strip.

Furthermore, from Figure 7 it can be seen that, due to the slope of water shedding portion 148, any water droplets that come into contact therewith rain that blows in, or water running down of the outside surface of the upper panel 1 00b) will simply run off and down the outside face of the lower panel 1 00a, rather than penetrating through into the wall cavity. The same may apply for dust and the like. This may help to eliminate or at least reduce the need to apply a line of sealant between the lower edge of upper panel 100b and the backing strip 140.

Finally, Figure 8 illustrates one way that the embodiment of the backing strip 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.

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

3. A backing strip as claimed in claim 2, wherein the said portion of the locating means that is configured to engage against the upper edge of the one or more lower cladding panels is further configured to extend outwardly at least some way over the top of the said upper edge and to sit on top of, and the rest against the said upper edge.
4. A backing strip as claimed in any one of the preceding claims, wherein the locating means includes a portion adapted to shed water. A backing strip comprising a first planar portion adapted to be positioned behind at least one relatively upper cladding panel, a water shedding portion extending below the first portion and sloping downwardly and outwardly with respect to the plane of the first portion, 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, and an engaging portion extending outwardly substantially perpendicularly to the plane of the first and second portions adapted to engage with at least a part of an upper edge of the at least one relatively lower cladding panels, the engaging portion extending between the top of the second portion and the bottom of the water shedding portion.