A reinforced composite roofing slate

Abstract

The invention relates to a composite roof tile which comprises a slate or stone tile bonded to an upper surface of a sheet of flexible water impermeable material The sheet of flexible material is offset with respect to the slate or stone tile to define a vertical overlapping edge on of flexible material and a vertical overlapping edge of the slate or stone tile. At least two strips of resiliently deformable material define a vertical capillary gap, an upper surface of the flexible water impermeable material and at least two strips of resiliently deformable material define a horizontal capillary gap on an underside of the flexible water impermeable material arranged to contact an overlaid slate or tile. The slate or stone tile is bonded to the upper surface of the sheet of flexible water material by at least two, preferably at least three, discrete stripes of adhesive which extend from a top region of the composite roof tile to a lower region of thereof to define drainage channels to drain water trapped between the slate or stone tile and the sheet of flexible material.

Description

[0001] A Reinforced Composite Roofing Slate

[0002] Field

[0003] The invention relates to a roofing slate and more particularly to a reinforced roofing slate in the form of a composite tile comprising two or more components.

[0004] Background

[0005] There are many examples of composite tiles which typically comprise a traditional slate or stone tile mounted on a flexible waterproof backing, such as a glass reinforced polymer (GRP) substrate or similar flexible membrane.

[0006] Although these were generally successful some did suffer from a number of drawbacks.

[0007] These drawbacks include the fact that during installation, with some types of composite tile, that during installation, there is often unacceptable levels of breakage due to their brittleness. This led to wastage and so increased overall build costs and so led to these roofs being considered too expensive.

[0008] Another problem was that sometimes long lengths of the waterproof backing was problematic during installation and proved dangerous to handle during high wind conditions.

[0009] Another problem was that some types of manufacturing processes used to fabricate the waterproof backing, were expensive because of initial design requirements.

[0010] A further problem was that certain types of composite tiles could not be installed onto fully boarded roof applications due to the fact that often, when used to span wider gaps, the composite tiles were subjected to stress and so prone to fracturing. A further problem was that traditional mechanical fixing methods available were not always suitable because of wind uplift regulations and excessive slate breakages at slate fixing locations.

[0011] Prior Art

[0012] Our UK patent application number GB 2 599 458 (Adverge Limited) describes a composite tile which although successful did encounter some drawbacks. For example, when not properly installed or when damaged, cracks in a composite tile, led to water ingress which in turn led to frost damage to the composite tiles or to the underlying a flexible waterproof backing which risked water damage to a roof or property.

[0013] For example, during installation the planar design of the lightweight GRP waterproofing layer was problematic especially when installing in windy conditions. There was a risk that longer lengths were blown away or even risked the installer being unbalanced which represented an unacceptable safety risk when working at height.

[0014] Adhesion of rows of slates to a waterproofing backing layer is known. This technique requires that slates are installed onto roofing boards that support the slates. However, installation, in the so-called ‘open rafter’ manner requires individual slates to accommodate structural movement in the roof and also to act independently when they span gaps between battens. As such, slates applied in this manner are required to have significant structural integrity. Consequently, it has been found that some types of flexible waterproof backings were not suitable for use in this ‘open rafter’ configuration.

[0015] Modem developments in adhesive performance permits a strong bond to be formed between the slate and a GRP waterproofing layer. When combined in this way the hardness of the slate and high tensile strength of the GRP provides a composite with considerably improved strength and load carrying capability. So that the composite is both strong and are able to sustain the weight of an installer as the tiles are being installed. Such newer composite tiles are increasingly considered safe and acceptable for use in the ‘open rafter’ configuration.

[0016] Several other attempts were made to address the aforementioned problems.

[0017] However, during weather testing, it was shown that, when installed on the roof, in some cases water was prone to being trapped in voids created between slates or stone tiles and the upper surface of a sheet of flexible material (GRP). This water ingress has been found to occur around the adhesive that bonded the slate or stone to the sheet of flexible material (GRP). On very sunny days trapped water heated and vaporised which sometimes led to failure of a bond. On cold days trapped water sometimes froze, expanded and this in turn has led to damage of the exterior of the composite tile.

[0018] One example is described in UK patent Application GB 2 249 112 (Thomas Brown et al) which describes a mounting device for natural quarried slates. The device comprises a backing plate having a front face on which one or more natural slates are mounted. The backing plate has oppositely directed, double channels which enable engagement of backing plates in such a way that rainwater is unable to pass through the device and is channelled down a roof.

[0019] Another example is described in UK patent Application GB 2 599 921 (Hambleside Danelaw limited) which discloses a roof covering mounting unit having a roof facing underside and a header rail. On a side edge is an interlocking feature which is deformable to facilitate expansion and contraction in a lateral direction. A spacing element is disposed on an underside of the main body and defines a height which is higher at the header end compared to the opposite end to allow water run-off. The mounting unit may support slates, tiles or solar panels such as photovoltaic (PV) cells.

[0020] The present invention arose to overcome these problems.

[0021] Another aim of the present invention is to improve the performance and speed of installation of flat discontinuous roofing products, such as slate, stone and clay. Summary of the Invention

[0022] According to a first aspect of the invention there is provided a composite roof tile comprising: a first slate or stone or clay tile which is bonded to an upper surface of a sheet of flexible material which is water impermeable, the sheet of flexible material is positioned offset, with respect to the first slate or stone tile, to define (i) a vertical edge on the sheet of flexible material, which when installed is laterally overlapped by an adjacent composite roof tile, and (ii) an area of first slate or stone tile which overlaps a vertical edge of a sheet of flexible material of an adjacent composite roof tile; the vertical edge extends from an upper edge to a lower edge of the sheet of flexible material and has at least two strips of compressible material affixed thereto which are positioned parallel one to another to define a vertically extending capillary gap therebetween; and on an underside of the sheet of flexible material there are at least two strips of compressible material, extending widthwise, from a lefthand side to a righthand side that are positioned parallel one to another to define a horizontally extending capillary gap therebetween, and which are dimensioned and arranged to contact upper surfaces of an overlapped row of slates or tiles; wherein the first slate or stone tile is bonded to the upper surface of the sheet of flexible material by at least two, discrete stripes of adhesive which extend from a top region of the sheet of flexible material to a lower region thereof thereby defining drainage channels between the first slate or stone tile and the sheet of flexible material to drain water trapped therebetween.

[0023] The compressible material is typically a long life, weatherproof, synthetic foam or rubber such as ethylene propylene diene monomer (EDPM). An important feature of this type, and similar types, of compressible material is that it is compressed to a height to conform to contours of the slate (or stone) tile. In the event of tiles lifting or rattling in very high winds, when a tile may lift and allow the compressible material to recover or expand, the compressible material deforms and compresses to allow the tile to reseat and reform a weatherproof seal. The terms foam strips and compressible material are therefore used interchangeably hereinafter.

[0024] As the sheet of flexible material is positioned offset with respect to the first slate (or stone tile) to define a vertical edge, this ensures it laterally overlaps the first slate (or stone tile) and so extends longitudinally along an upper surface of the sheet of flexible material. This is explained below with reference to Figures 2 and 4.

[0025] Preferably at least two strips of compressible material are affixed to the sheet of flexible material and re positioned substantially parallel one to another, thereby defining a capillary gap between the at least two strips of compressible material as described below in Figures 4 and 7.

[0026] As the at least two strips of resi liently deformable material are bonded to a layer of to an upper surface of a lower slate or stone tile along its lower edge, it is appreciated that at least two strips of resiliently deformable material, defining a capillary gap, may be affixed to an underside surface of an overlaid slate or stone tile along its lower edge. The important fact is that the strips of compressible material are dimensioned and arranged to be sandwiched between two overlapping slates or stone tiles so that a capillary gap is defined between the strips of compressible material.

[0027] The strips of compressible material may be applied by a machine and cut to length automatically so as to ensure their correct orientation with respect to a lower edge of a tile (or stone) slate and to ensure consistency of the gap between the at least two adjacent strips of compressible material.

[0028] Advantageously the at least one strip of compressible material is adapted to contact an underside of the adjacent second slate or tile such that the second slate or tile overlaps the sheet of flexible material when in contact with the at least one strip of compressible material.

[0029] It is appreciated that when the composite tile is installed with the at least three, discrete stripes of adhesive in a vertical orientation unwanted moisture or water is able to drain under gravity. In addition, these stripes of adhesive provide additional strength to the composite slates so that they are better able to span gaps between battens.

[0030] Water seals are specifically placed to the sides of the capillary bar prevents leaks caused by lateral movement of tracking water. An advantage of the compressible material or foam strip(s) which is (are) affixed to the vertical overlapping edge of the sheet of flexible material to contact an underside of an adjacent slate or tile is that they act as a side lap which allows lateral horizontal movement to occur in the roof and structure. By enabling this movement to be a structural movement, a water channel is effectively provided that prevents a porous foam seal from drawing water through itself.

[0031] As an alternative a cured adhesive material foam strip(s) which is compressible may be used along vertical and / or horizontal sides of the composite tile.

[0032] In addition, it has been found that application of an adhesive around the fixing holes for nails or screws, reduces point loading effects and therefore helps to prevent slate fracture at the point of fixing.

[0033] Parallel foam tape, applied to an underside of a composite tile allows for structural movement and creates a secondary water channel to prevent drawing water through the seal at overlap of courses of composite tiles, thereby eliminating any sideways ingress, for example that can occur when wind is blowing rain in a particular direction.

[0034] In some embodiments each strip of compressible material is at least 10 mm wide, preferably at least 15 mm wide and most preferably at least 20 mm wide.

[0035] In some embodiments the capillary gap defined between at least two strips of compressible material is at least 5 mm wide, preferably at least 15 mm wide and most preferably at least 20 mm wide.

[0036] In some embodiments the at least two strips of compressible material are at least 1 mm in height.

[0037] In some embodiments an adhesive material is applied around a fixing hole to reinforce the fixing holes.

[0038] In some embodiments the sheet of flexible material includes a ridge extending along an upper edge thereof which acts as a clip or hanger to attach to a batten. In some embodiments an upper edge or head has a trough formed therein. Optionally the trough is formed as a U-shaped profile, preferably wherein one side / wall of the U- shaped trough is formed from the upper edge or head of the slate or stone member, and the other wall / side is formed from the pre-formed planar sheet.

[0039] In some embodiments the discrete stripes of adhesive which define drainage channels are spaced apart one from another not less than 50 mm, preferably not less than 60 mm and most preferably not less than 70 mm.

[0040] According to a second aspect of the invention there is provided a method of installing a composite roof tile as hereindefined comprising the steps of placing a roof tile mounting component onto a roofing board, affixing a ridge member to an upper side surface of a roof batten and affixing the composite roof tile to the top surface of the roof tile mounting component.

[0041] Preferably the step of affixing the head member to an upper side surface of a roof batten and / or the composite roof tile to the top surface of the roof tile mounting component includes using a screw means, preferably a non-ferrous screw.

[0042] Composite roof tiles may be installed in a single lap configuration.

[0043] Furthermore, this compressible foam side lap allows for shunting adjustments to facilitate roof alignment during installation.

[0044] Preferred embodiments of the invention will now be described, by way of examples only, and with reference to the Figures in which:

[0045] Brief Description of Drawings

[0046] Figure 1 is a diagrammatical section view showing a traditional double lapped series of overlapping slate or stone tiles; Figure 2 is a diagrammatical section view showing an orthographic view of the traditional double lapped installation of slate or stone tiles and indicates a broken bond which can occur in vertical joints;

[0047] Figure 3 shows an example of two separated components of the invention composite slate tile and the previously prepared glass reinforced plastic (GRP) base prior to factory assembly;

[0048] Figure 4 shows an orthographic view of the final embodiment of the composite slate tile;

[0049] Figure 5 shows a top view of one embodiment of the composite slate tile highlighting the offset nature of the attachments of the composite slate tile to the GRP to create a side lap;

[0050] Figure 6 shows a side view of the profile of the composite slate tile;

[0051] Figure 7 illustrates an example of an installed composite slate tile onto battens in an ‘open rafter’ application; and

[0052] Figure 8 shows the detailed installation of the composite slate tile that is suitable for installation onto boarding as well as the specially designed screw fixings.

[0053] Detailed Description of Preferred Embodiments of the Invention

[0054] Referring to Figure 1 which shows an example, in diagrammatical form of a traditional thin, flat and rectangular roofing products such as slates (A) and stone are installed on a roof by mounting them onto rows of roofing battens (T) so that they span the gaps created between those rows of battens, these rows, or courses, of battens are installed laterally onto a roof frame of a building in rows that coincide with the size of the slates to be used. The double lapping or layering of the slates provides combined strength to the finished roof covering. Figure 2 shows an overall view from above of the traditional double lapped installation of slates and stone and shows broken bonds of the vertical joints as shown by VJ.

[0055] Figure 3 shows an example of two separated components 117 and 118 of one embodiment of a composite slate tile and supported on a sheet of glass reinforced plastic (GRP). The fabrication of the composite slate tile is described in greater detail below.

[0056] Individual composite slate tiles are positioned perpendicular across supporting timber battens (not shown) on which they are mounted so that the rectangular slates span at least 3 battens vertically as shown in Figure 3, when installed in the traditional ‘open rafter’, in a double lap arrangement.

[0057] Composite slate tiles or ‘slates’ are installed so that that the head, or top of the slate is cited at the midpoint of each, ascending longitude batten and partially overlays the course of slates previously installed below, by this method the slates are installed in a ‘double lap’ or layered manner so that each ascending course or row is staggered (broken bond) whereby the side of each slate is positioned at the midpoint of the slate below so as to provide a waterproofing layer below the vertical abutment joints of the slates in the course above.

[0058] By this method, as rainwater permeates through any open vertical abutment joints (Figure 2, VJ), it lands on the slate below and is expelled from the roof by means of gravitational forces created by the roof pitch (or incline of the roof surface, Figure 1 , OPI).

[0059] A benefit of this double layering of the slates is that it provides additional strength and integrity to the slate roof covering by creating a double thickness of slate at all points on the roof surface, this double layer of slates offers the support to the upper layers of slates that is necessary when access to the roof surface is required during installation or maintenance (Figure 1 , DL).

[0060] Slates that are traditionally installed on the roof according to the double lap method are pre-holed in a position approximately centrally in the slates so that they can be mechanically fixed or nailed to the roof mounting battens. Slates are brittle and contain natural grain or coursing, the pre-holing of slates creates a structural weakness in the slates, holes that are placed in the central region of the slate increases the solid portion of slate between the edge of the slate and the holes and thus reduces the fracture risk along the grain of the slates. Because the slates are fixed at the mid-point, the use of nails, in conjunction with the additional layering of the slates is sufficient to resist the wind-uplift effects in severe weather conditions.

[0061] When slates were installed in the single lap method whereby a separate and flexible waterproofing layer is sited below, and the two elements acted independently and separately and did not provide any required improvement in structural integrity of the slates. In addition, slates installed in the single lap method require the slates to be pre-drilled with holes at the top edge of the slates for fixing (Figure 3, AH). It is commonplace to access the roof during installation, and it was discovered, through testing, that it was not practical to access the roof without causing excessive breakages to the previously installed slates below. Predominantly, breakage of the slates occurred at the weakness created around the fixing holes thus releasing the slates from their position on the roof causing slates to fail and thereby compromising the weatherproofing of the roof.

[0062] Referring to Figure 3, which shows a partly formed composite tile, there is shown parallel stripes of an adhesive (Z) which bond the stone or slate tile to the sheet of flexible material which is water impermeable. The adhesive is chemically compatible with both the slate and the sheet of flexible material which is water impermeable which may be a specially manufactured GRP waterproofing and reinforcing layer. Drainage channels CH are defined between the stripes of adhesive.

[0063] Further research and development showed that when the adhesive is installed in vertical parallel lines between the GRP waterproofing layer and the slate (Figure 3, Z), that it provided sufficient support so that the finished composite slate tile developed the desired combined integral strength so that it could now span the battens without fracturing when pressured or accessed during installation. The space between these parallel lines of adhesive Z is ideally not less than 65 mm (Figure 3, CH). One advantage gained from the vertical application of the adhesive (CH) from top to bottom created drainage channels that, in the event of rainwater seepage or leakage, ensures free drainage of any water being trapped between the slate and the GRP layer.

[0064] In a particularly preferred embodiment, the formation of a required capillary bar and overlaying tile engagement layer may be combined into an ‘S’ shaped profile, as shown for example as feature ‘S’ in Figure 7. This is considerably easier to fabricate and provides additional structural integrity to the profile, whilst still maintaining performance requirements of the inbuilt features (102 and 116). Inner exposed end of the capillary channel is formed below the capillary bar, when the slate or tile is fitted in place, and the head of the slate is sealed by side laps 117 and 118 along one edge as shown in Figure 3, to prevent water tracking laterally towards an open element of the abutment joint and thereby maintain its requirement for waterproofing.

[0065] The at least two strips of compressible material 15X are affixed to the underside of slate A and are positioned substantially parallel one to another, thereby defining a capillary gap X between the at least two strips of compressible material.

[0066] The strips of compressible material may be applied by a machine and cut to length automatically so as to ensure their correct orientation with respect to a lower edge of a tile (or stone) slate and to ensure consistency of the gap between the at least two adjacent strips of compressible material.

[0067] The curved ‘S’ profile is efficient to manufacture, it strengthens the profile and still provides a required capillary break and so inhibits water ingress.

[0068] Specially designed, non-ferrous, extremely low profile, large flange head, GRP drilling screws F are ideally used to fix the slates through holes AH at the head of the slate. This helps to avoid stress fractures that may be caused by bending when slates are lifted, for example in high winds or during storm conditions. The screw has a selfdrilling tip designed to penetrate GRP layer and self-seating serrations to neatly bed into and engage the slate for a self-made fit. The system is designed to be used in the application shown in Figure 4, for use in open rafter applications. However, this application does not restrict the invention being used as a composite slate tile. Therefore, when the composite slate tile is used on fully boarded applications, for example as shown at B in Figure 8, the batten engagement curve may be replaced with a fixing flange SB, SF that incorporates the upper capillary bar features 102 and 116 and allows additional fixing of the composite slate tile through the flange SF directly onto flat roofing boards B.

[0069] With the slates adhered to the GRP using the adhesive in vertical lines Z and around the fixing holes AH, the composite slate tile was re-tested. The composite slate tile is installed onto roofing battens using nails in the traditional manner. However, it was discovered that, when the composite slate tile is installed when nailed at its top edge (or head of the slate), it was shown that the bottom (or toe) of the slate could be easily leveraged upwards so as to pry the nails from the battens. In most jurisdictions it is a legal requirement that roof coverings should withstand the ‘wind uplift’ forces exerted upon them during adverse weather conditions slates must be fixed to the roof and be fit for purpose to prevent them from being lifted or blown off the roof at any time.

[0070] The use of conventional screws for fixing the composite slate tile proved problematic. Pointed screws were found not to gain sufficient purchase and draw through the GRP layer of the composite slate tile. Predrilling of the GRP layer creates a leak risk and was not suitable as well as proving very time consuming. In addition, the countersunk head of the screw, when seating itself, acted as a driving wedge and risked fracturing the slates at the fixing point. Raised head screws were not suitable as they lifted the slate that was installed above said screw.

[0071] Consequently, a non-ferrous screw was proposed and is shown as F in Figure 8. Screw F has a self-drilling head (FD) that drives through the GRP without the need for first pre-drilling. In addition, the screw F has a much large format thin disc head FH that holds the slate in compression without causing a fracture and does not interfere the overlaying slate. In order to properly seat the screw F onto what may be an irregular surface of the slate, the top of the screw shaft is splayed and serrated (FS) so that it cuts or grinds into the surface of the slate and thus forms a unform seat onto the slate. This engagement of screw onto slate forms a seal and also provides a uniform pressure point to prevent the fracture of the slate. Self-drilling screws are known, as are large format head screws but the combination and application are an innovative use of known elements in a new and innovative application. The use of the specially adapted screws permits the composite slate tile to be installed in full compliance of the legislative requirements for wind-uplift.

[0072] Because of the varied nature of natural slates and large variations in their sizes and applications, the invention is intended to be manufactured in the singular application for use in both the open rafter and fully boarded applications. By their very nature, slates are not perfectly flat and often have a riven surface, the uneven nature of the surface of slates is not compatible to the use of adhesive tapes.

[0073] In addition, the invention is intended to enable slates to be reused and therefore does not incorporate the use of adhesives beyond the manufacturing process. Adhesives do not form part of the installation process. So as to maintain weatherproofing to the vertical abutment joint a side lap is used as shown for example by Y in Figure 4. Side laps are a common feature in roofing and are known to be used in conjunction with preform water channels and / or adhesives.

[0074] As mentioned earlier slates are not perfectly flat. Therefore, in order to weatherproof the side lap (Figure 3 and Figure 4, Y) a foam seal is adhered to an upper face of the GRP so as form a waterproof seal when an adjoining slate is overlaid on it. However, testing showed that, during high pressure atmospheric conditions, it was still possible to draw water across and so beyond the foam seal.

[0075] The invention uses a t least two sets of parallel strips of compressible foam (16X) that are pre-applied to the upper portion of the side lap element Y as shown in Figure 3. The first line of foam seal tape prevents the direct tracking of water across the side lap, the gap between the foam seals X represents a secondary water barrier that prevents the further tracking of water in the event that water is transmitted through the foam, the foam is of such a height and thickness so as to prevent the transmission of water by means of capillary action across the gap or capillary channel indicated as X.

[0076] A third feature is provided to the side lap by means of a second foam seal to the outer edge of the side lap. Extensive testing has shown that a gap or capillary channel (X) of no less than 10 mm prevented the transfer of water between the two lines of foam. The use of compressible foam strips formed an adequate seal to the riven and uneven surface of the slate.

[0077] The side lap is specifically sized to permit the simple manufacturing and off-site assembly of the composite slate tile. By not using adhesives or water channels to the side lap the width of the channel can easily be altered and adjusted during installation to as to align the slates so as to be neat and uniform when installed, the foam side lap can be easily adjusted or aligned by opening or closing the abutment gap within parameters to allow the composite slate tile to be ‘shunted’ so as to be aligned with other composite slate tile and the edge of the roof.

[0078] During testing, it was shown that water could collect at the head of the slate in the capillary channel and in could track laterally across the top of the slate in the space of the capillary void 116. The side lap tapes are therefore installed higher ‘up the curve’ of the GRP layer as shown by 118 in Figure 3, to provide an additional barrier to ensure that any water at the head of the slate is prevented from tracking across the barrier created by the tapes 16X and thus the composite slate tile remains waterproof. In addition, a rubberised seal 117 is placed at the opposite end of the channel to prevent trapped water form tracking in the opposite direction. By this method, trapped water is released by draining between the slate or tile and the layer of water impermeable flexible material, such as GRP, through the channels CH defined between the stripes Z of adhesive material as shown in Figure 3.

[0079] Test results showed a considerable reduction in the amount of water that is able to transfer through or under the single strip of foam than is able to pass across two strips of foam (15X) that are separated by a transfer resistance channel X. Through the use of two pre-installed foam tapes 15X that are separated with channel between them, the weather resistance of the composite slate tile is therefore considerably improved. Traditional slates that are installed in the traditional double lapped method (Figure 2) have a uniform visible lower portion of the slate (A). This is accepted as being the traditional look of a slate roof covering. Although there are many varied sizes of slates it is commonplace predominantly to use only 2 sizes, in order to imitate the appearance of these two common sizes of slates used to form a traditionally installed roof covering.

[0080] The composite slate tile, when installed in the single lap application, is required to be made in one of two sizes, those being 350 mm long by 300 mm wide and also 300 mm long by 250 mm wide. By this method, when installed, the composite slate tile is aesthetically indistinguishable from the most common slate roof applications. However, this does not restrict the composite slate tile from utilising a variety of alternative sizes of slate and stone.

[0081] When attempting to replicate a traditional ‘random’ stone roofing appearance, it was discovered that the combination of stone sizes that are all 400 mm long and 300 mm wide, 450 mm wide and 600 mm wide could be easily mixed and combined in what then appears to be a random arrangement and so replicates the desired effect of a traditional build, whilst at the same offering a greatly simplified method of installation with superior weather resistance.

[0082] Traditionally, individual slates are installed in a double lap method. By use of the innovative methods, whereby individual slates are bonded to a high tensile GRP backing plate in such a way as to release trapped moisture and yet also achieve a high level of combined strength and integrity, and in conjunction with the introduction of a side lap that incorporates a flexible, non-adhered, parallel set of foam seals, and through the use of specially adapted screws, it is now possible to install individual slates, that are properly secured to the roof, in similar manner as would preformed concrete tiles be installed so that they are robust and fit for purpose.

[0083] The invention has been described by way of examples only and it will be appreciated that variation may be made to the aforementioned embodiments without departing from the scope of protection as defined by the claims. For example, the water impermeable material is not limited to being formed from GRP, it may comprise extruded synthetic plastics membrane or roll formed metal.

[0084] Likewise, although reference has been made to the composite tile be applied to a roof, the tile may also be suitable for use as a vertical tile hanging tile, rainscreen or exterior cladding that retains fire resistant properties.

Claims

Claims1 . A composite roof tile comprises: a first slate or stone or clay tile which is bonded to an upper surface of a sheet of flexible material which is water impermeable, the sheet of flexible material is positioned offset, with respect to the first slate or stone tile, to define (i) a vertical edge on the sheet of flexible material, which when installed is laterally overlapped by an adjacent composite roof tile, and (ii) an area of first slate or stone tile which overlaps a vertical edge of a sheet of flexible material of an adjacent composite roof tile; the vertical edge extends from an upper edge to a lower edge of the sheet of flexible material and has at least two strips of compressible material affixed thereto which are positioned parallel one to another to define a vertically extending capillary gap therebetween; and on an underside of the sheet of flexible material there are at least two strips of compressible material, extending widthwise, from a lefthand side to a righthand side that are positioned parallel one to another to define a horizontally extending capillary gap therebetween and which are dimensioned and arranged to contact upper surfaces of an overlapped row of slates or tiles; wherein the first slate or stone tile is bonded to the upper surface of the sheet of flexible material by at least two, discrete stripes of adhesive which extend from a top region of the sheet of flexible material to a lower region thereof thereby defining drainage channels between the first slate or stone tile and the sheet of flexible material to drain water trapped therebetween.

2. A composite roof tile according to claim 1 wherein the sheet of flexible material is glass reinforced plastic (GRP) and is adapted to abut or be applied to a roofing batten or roofing board.

3. A composite roof tile according to claim 1 or 2 wherein the at least two strips of compressible material, defining the vertically extending capillary gap and / or the horizontally extending capillary gap, are formed from a resil iently deformable material, such as foamed rubber or foamed synthetic polymer material.

4. A composite roof tile according to claim 3 wherein each strip of compressible material is at least 10 mm wide, preferably at least 15 mm wide and most preferably at least 20 mm wide.

5. A composite roof tile according to claim 3 or 4 wherein the, or each, capillary gap defined between at least two strips of compressible material is at least 5 mm wide, preferably at least 15 mm wide and most preferably at least 20 mm wide.

6. A composite roof tile according to any of claims 3 to 5 wherein the at least two strips of compressible material are at least 1 mm in height.

7. A composite roof tile according to any preceding claim wherein an adhesive material is applied around a fixing hole to reinforce the fixing holes.

8. A composite roof tile according to any preceding claim wherein the sheet of flexible material includes a ridge extending along an upper edge thereof which acts as a clip or hanger to attach to a batten.

9. A composite roof tile according to claim 8 wherein the ridge has a U-shaped trough formed by the sheet of flexible material.

10. A composite roof tile according to claim 9 wherein the U-shaped trough extends to an S-shaped profile formed by the sheet of flexible material.

11. A composite roof tile according to any preceding claim wherein the discrete stripes of adhesive which define drainage channels are spaced apart one from another not less than 50 mm, preferably not less than 60 mm and most preferably not less than 70 mm.

12. A method of installing a composite roof tile as claimed in any preceding claim comprising the steps of: placing a roof tile mounting component onto a roofing board or batten; affixing a first composite roof tile to a top surface of the roof tile mounting component and exposing its overlapping vertical edge of a sheet of flexible material and overlapping the exposed vertical edge of the sheet of flexible material with an overlapped edge of slate or stone tile of a second adjacent composite roof tile; and sandwiching the at least two strips of compressible material between the first andsecond adjacent composite roof tiles to define a vertically extending capillary gap therebetween.

13. A method as claimed in claim 12 wherein the step of affixing the ridge member to an upper side surface of a roof batten and / or the composite roof tile to the top surface of the roof tile mounting component includes using a screw means, preferably a non-ferrous screw.

14. A method as claimed in either claim 12 or 13 wherein composite roof tiles are installed in a double lap configuration.

15. A method as claimed in any of claims 12 to 14 wherein a subsequent row of overlaid composite roof tiles is installed on an underlying row of composite roof tiles such that the at least two strips of compressible material which define the horizontally extending capillary gap, on the undersides of adjacent sheets of flexible material, are positioned such that they are sandwiched between upper surfaces of an overlapped row of slates or tiles.

16. A single lap method comprising the composite roof tile of any of claims 1 to 11 , where the size of the slates are at least 350 mm long by 300 mm wide.

17. A single lap method comprising the composite roof tile of any of claims 1 to 11 , where the size of the slates is between 300 mm long by 250 mm wide.

18. A single lap method comprising the composite roof tile of any of claims 1 to 11 , where the size of the stone slates is at least 400 mm long and 300 mm wide and preferably at least 450 mm wide and 600 mm wide.

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