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 This invention concerns the use of mesh to form a screen in a gutter. It is particularly applicable, although not restricted to, the use of mesh made from plastics materials to screen the gutter along the edge of a roof of a building for the purpose of preventing the entry of unwanted materials such as sticks, leaves, fruit, nuts and other tree debris, large insects, litter and the like into the guttering. The mesh may also serve as a barrier to birds and small animals such as rats and possums from entering the roof cavity of the building.
 In some places such a gutter is called guttering and spouting, but the general shape remains the same being a thin-walled open topped channel, usually made of metal or plastics material, positioned to collect rainwater as it runs off a roof and gently sloped to deliver the water to one or more discharge points.
 It is well known that the collection of unwanted materials in roof gutters causes overflowing of the guttering, blockage of the outflow pipes, constitutes a fire hazard and contributes to corrosion of the gutter. It also contaminates any water collected from the roof for drinking or other domestic purposes.
 Many systems are in use, and more have been proposed, which provide a screen of mesh to cover the top of the gutter. One particularly successful method of covering gutter with mesh is described in the present applicant's Australian Patent No. 726947. That method involves running a strip of mesh, 25 cm to 100 cm wide, for the full length of a run of gutter and affixing one longitudinal edge of this strip to the roof material and the opposite edge of the mesh strip to the upper outside edge of the gutter. Such a system is shown in
 U.S. Pat. No. 5,956,904 describes a dual screen which is inserted into the upper part of the gutter. The dual screen is in strip form and is somewhat wider than the gutter width. The screen is flexed so as to adopt an arcuate working position spanning the gutter. This is satisfactory so long as the gutter does not change shape when brimful of water during downpours or when compressed by tradesmen's ladders. Such forces tend to dislodge the free edge of the screen.
 The mesh in such systems must be kept somewhat tensioned between rigid fastenings on the roof and the top outer edge of the gutter in order for the leaves and sticks to slide over the edge of the gutter. While such installations are very effective, their success relies upon skilled installation, the cost of which many potential users would prefer to avoid.
 Many do-it-yourself screening systems are marketed which use a strip of mesh which is placed into the gutter in the shape of an inverted channel. Such an arrangement is shown in
 Typically the aperture size of the mesh used in such user-installed systems ranges from about 15 mm to about 5 mm, whereas for mesh used in the professionally installed systems, the aperture size is typically in the range from about 5 min to about 2 mm. For the coarser sizes, the holes in the mesh are so large that mush material passes through. This material often blocks downpipes and drains, can build up in the gutter and can also contaminate water stored in tanks.
 A more important problem about large sized mesh however is that sticks and leaf stems easily become caught in it. Trapped in this way, they protrude up from the mesh thus creating a barrier to the escape of other debris and the mesh thus provides a solid anchor for the build-up of further debris around the gutter area on a roof. A further disadvantage of larger mesh sizes for do-it-yourself installations is that there is less strength available from the plastic stands so there is an increased tendency for the mesh to collapse.
 Meshes used in user-installed systems are often thin and flimsy so that they protrude out and up from the gutter or they are easily dislodged thereby allowing unwanted entry of debris and look unsightly.
 With meshes having the smaller aperture sizes, leaves and sticks are not so readily caught, but water running from the roof has a much greater tendency for “sheeting” or running over the top of the mesh rather than falling through the apertures into the gutter. The choice of aperture size can thus greatly affect performance of a mesh.
 Some meshes used in user-installed systems come only in fairly short (about 1 metre) lengths and the “cut” ends easily dislodge and come out of the gutter.
 An aim of the present invention is to provide a mesh and a gutter screening system which is suitable for do-it-yourself installation and alleviates disadvantages of the prior art.
 Accordingly, in one aspect the present invention provides a screen placed within a gutter, said screen comprising a tubular sleeve of mesh, said sleeve at least substantially filling the gutter.
 In another aspect, the invention provides a tubular sleeve of mesh of plastics material for positioning within a gutter to prevent the entry of unwanted materials into the gutter, said mesh comprising a first array of parallel strands aligned in a first direction integrally moulded with a second array of parallel strands angularly offset to the first array, said strands defining mesh apertures therebetween.
 In a further aspect, the invention provides a method of preventing the entry of unwanted materials into a gutter, said method comprising fitting into the gutter a tubular sleeve of mesh, the length of which extends along the gutter, whereby the sleeve at least substantially fills the gutter.
 The gutter may be positioned on an outside edge of a roof of a building. The mesh may be formed of metal, but is preferably a screen formed of plastics material.
 Alternatively, the gutter may be at or near ground level and may be let into the surface of a driveway for motor vehicles, swimming pool surround, walkway or the like.
 The sleeve preferably extends continuously along at least substantially the full length of said gutter.
 The mesh preferably comprises a first array of strands aligned in a first direction overlaid by and adhered to a second array of strands aligned approximately at right angles to said first direction. More preferably, the mesh comprises:—
 a first a=ray of parallel strands, hereinafter called longitudinal strands, aligned in the longitudinal direction of the sleeve, and
 a second array of parallel strands, hereinafter called circumferential strands, integrally moulded with and aligned at right angles to the first array, said first and second arrays of strands defining mesh apertures therebetween.
 Preferably, the apertures are sized between 2.5 mm and 4.0 mm in a first direction and between 3.5 and 6.0 mm in a second direction transverse to said first direction.
 The strands in said first array may be spaced closer than the strands of the second array. The apertures through the mesh may be of generally elliptical shape which is longitudinally aligned in the direction of the second array.
 The ends of said sleeve may be closed in order to prevent ingress of debris to the interior of the sleeve. Such closure may be by fastening the end of the sleeve flat, with or without first folding the end over. Alternatively, the closure may be achieved by trimming the end of the sleeve to form a flap which is then folded over to a position about transverse to the longitudinal axis of the sleeve where it is then fastened across the end of the sleeve. The fastening may be by any suitable means, such as by staples, clips or adhesive.
 In order that the invention may be more fully understood, there will now be described, by way of example only, preferred embodiments and other elements of the invention with reference to the accompanying drawings, where:—
 Referring to the prior art installation shown in
 Referring to the prior art installation shown in
 Referring to
 As shown in
 The sleeve
 As an alternative to the tubular form being integrally moulded, the mesh may be moulded in a planar form and the longitudinal edges thereafter connected by fusing or otherwise fastening to produce the tubular structure.
 The mesh as installed has an outside face
 Where the strands
 Typical dimensions for the preferred mesh are:—
centre to centre spacing of longitudinal strands 42 3.5 to 6.0 mm centre to centre spacing of circumferential strands 44 2.5 to 4.0 mm thickness of mesh 2 mm
 The stands
 The ends of said sleeve are closed shut in order to prevent ingress of debris to the interior of the sleeve through the open end if it happens to become displaced from the end of the gutter. Most conveniently, such closure is by simply flattening the end of the sleeve and stapling, clipping, taping or otherwise adhering the end of the sleeve flat, with or without first folding the end over. Alternatively, the closure may be achieved by trimming the end of the sleeve to form a flap which is then folded over to a position transverse to the longitudinal axis of the sleeve, whereupon the flap is then fastened across the end of the sleeve.
 The sleeve forms a tubular sock which is not easily dislodged from the gutter, thereby ensuring no penetration of unwanted debris into the gutter channel.
 Even if the exposed top of the sleeve mounted within a gutter becomes covered with leaves, a completely clear tunnel is maintained along the centre of the sleeve, so allowing free-flow of water within the sleeve. This shape is evident in
 A panel may be cut from the sleeve at the place where it passes over a downpipe or other drain pipe for removal of water from the gutter. In this way, the water flowing down the inside of the sleeve has an unrestricted aperture to pass from the gutter into the drain pipe.
 Some guttering constructions utilise supporting brackets which are external to the guttering channel and such brackets cause no obstruction to the sleeve of mesh pushed into the guttering. However, some constructions of guttering have supporting brackets which are internal to the channel, with such brackets being nailed to the building's fascia
 The mesh tube is inherently resilient and may be flattened for rolling on to a reel
 When as in
 Whilst the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention. For example, although the above descriptions refer to strands having a generally circular cross section, it will be understood that they may alternatively be elliptical or even of squared or flattened cross section. Also, the moulding or forming operation to manufacture the mesh may also cause the strands at the crossing points to be slightly bulged, or to be flattened slightly, and mesh so produced will be understood to also fall within the scope of the invention.
 Also, although the preferred form of mesh is constructed as a pair of intersecting arrays of parallel strands, the mesh may alternatively take the form of a mat of randomly aligned fibres adhered to each other. In such an embodiment, the sleeves would have a substantially greater wall thickness than the sleeve of the preferred embodiment. The mat thickness could comprise up to 20% of the diameter of the sleeve.
 Also, although the preferred mesh is formed of plastics material, the mesh may alternatively be woven from metal wire or formed by a multitude of perforations through a metal sheet. The apertures may take the form of round or generally square holes, ellipses, slots or holes of any other shape desired. Both versions exhibit shape “memory” and stay in position in roof gutters for long periods without attention. They are easily cleared with a hose.
 Although the invention is described particularly in relation to roof gutters, it is also applicable to other gutters such as those formed as channels in concrete or other paving. Where used in places like driveways or paths, the sleeve would preferably be overlaid by a rigid structural grid to prevent downward loads flattening the sleeve within the gutter.
 It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.