A triple roof tile

Abstract

A single lap composite triple roof tile comprises a front leading edge and rear trailing edge and fist and second lateral side edges. The tile has an upper surface which is exposed when the roof is fi

Description

TECHNOLOGICAL FIELD Examples of the disclosure relate to a roof tile that has the appearance of three side-by-side roof tiles. BACKGROUND Traditional double lap plain rooftiles have no side interlocks and they are laid laterally, side-by-side, in an abutting, non-overlapping, arrangement Each part of a lateral join between laterally abutting tiles is either over-laid by an upslope longitudinally offset tile or under-laid by a downslope longitudinally offset tile. Single lap tiles have side (lateral) interlocks, and are laid laterally, side-by-side, in an overlapping arrangement. One of the side-by-side roof tiles has a lower side interlock and other of the side-by-side roof tiles has an upper side interlock. The lower side interlock and the upper side interlock overlap. As the side-by-side roof tiles protect the lateral join, upslope and downslope tiles do not need to overly and underlie the whole of the lateral join. An upslope part of a lateral join between laterally abutting tiles is overlayed by an upslope longitudinally offset tile and a down slope part of a lateral join is underlaid by a downslope longitudinally offset tile but there is also a part of the lateral join (between the upslope part and the downslope part) that is not overlayed by an upslope longitudinally offset tile and not underlaid by a downslope longitudinally offset tile. An advantage of single lap tiles is that less tiles are required per area of roof. A problem with single lap tiles is that a larger percentage of their area is exposed to the wind. This can increase shear force per area of exposed tile for single lap tiles compared to double lap tiles. This problem increases with the size of the tile. This can in part be addressed by using holes in the roof tile to allow them to be fixed to wooden roof battens. However, such holes can weaken the tile and are a potential source of water ingress. Furthermore there needs to be appropriately positioned battens. The side interlocks are often arranged to form drainage channels, so the drainage capacity of the roof is not compromised by using single tap tiles with interlocks instead of double lap tile without interlocks. In view of these technical constraints there is currently a standard size for a single lap roof tile of 26.7cm by 16.5 cm. The inventors have created a larger single-lap roof tile. It is strong yet light. It has improved interlocks. It has excellent drainage properties. It is robust to wind and rain. It has features to minimize water ingress. Furthermore the roof tiles are economic to manufacture and use. The roof tiles are designed to reduce damage in transit and are easily used at height. BRIEF SUMMARY According to various, but not necessarily all, examples there is provided examples as claimed in the appended claims. While the above examples of the disclosure and optional features are described separately, it is to be understood that their provision in all possible combinations and permutations is contained within the disclosure. It is to be understood that various examples of the disclosure can comprise any or all of the features described in respect of other examples of the disclosure, and vice versa. Also, it is to be appreciated that any one or more or all of the features, in any combination, may be implemented by / comprised in / performable by an apparatus, a method, and / or computer program instructions as desired, and as appropriate. BRIEF DESCRIPTION Some examples will now be described with reference to the accompanying drawings in which: FIGs 1-8 illustrate a new roof tile 100 with a single interlock arrangement. FIG 1 is an upper-front-side perspective view; FIG 2 is an upper-back-side perspective view; FIG 3 is an upper plan view illustrating the upper surface 100; FIG 4 is a side view illustrating side edge 106; FIG 5 is a side view illustrating side edge 108; FIG 6 is a front view illustrating the front leading edge 102; FIG 7 is a back view illustrating the rear trailing edge 104; FIG 8 is a lower plan view illustrating the lower surface 200; FIGs 9-11 illustrate a new roof tile 100 with a double interlock arrangement. FIG 9 is an upper plan view illustrating the upper surface 100; FIG 10 is a lower plan view illustrating the lower surface 200; FIG 11 is a front view illustrating the front leading edge 102; FIGs 12-15 illustrate a new roof tile 100 with a single interlock arrangement. FIG 12 is an upper-front-side perspective view; FIG 13 is an upper plan view illustrating the upper surface 100; FIG 14 is a lower plan view illustrating the lower surface 200; FIG 15 is a front view illustrating the front leading edge 102 FIGs 16a, 16B illustrate a system using rooftiles 100. The figures are not necessarily to scale. Certain features and views of the figures can be shown schematically or exaggerated in scale in the interest of clarity and conciseness. For example, the dimensions of some elements in the figures can be exaggerated relative to other elements to aid explication. Similar reference numerals are used in the figures to designate similar features. For clarity, all reference numerals are not necessarily displayed in all figures. In the following description a class (or set) can be referenced using a reference number without a subscript index (e.g. 10) and a specific instance of the class (member of the set) can be referenced using the reference number with a numerical type subscript index (e.g. 10_1) and a non-specific instance of the class (member of the set) can be referenced using the reference number with a variable type subscript index (e.g. 10J). DETAILED DESCRIPTION The following description relates to the enclosed figures. The roof tile 100 illustrated is a single lap plain roof tile with a lateral interlock 300. The rooftile 100 is a ‘triple’ roof tile. It is a single roof tile but has the appearance from the ground of being three side-by-side roof tiles (referred to as mock rooftiles 101). The rooftile 100 has an upper surface 110 that is exposed when the rooftile 100 is fitted. The rooftile 100 has a lower surface 200 that is hidden when the rooftile 100 is fitted. The rooftile 100 has interlocks 300 including a lower interlock 300_1 and an upper interlock 300_2. The rooftile 100 has a front leading edge 102, a rear trailing edge 104, a side edge 106 associated with an overlock 300_2 and a side edge 108 associated with an underlock 300_1. In the examples illustrated the upper surface 110 is chamfered at its side edges. When a rooftile 100 is interconnected with another roof tile 100 in a side-by-side arrangement, the side-by-side chamfered side edges of the upper surfaces 110 of the side-by-side roof tiles 100 form a joint. The joint has the shape of a channel, formed from the opposing chamfered edges, that extends the length of the roof tiles 100 and has a lateral width W at the upper surface 110. The upper surface 110 of the rooftile 100 has a pair of parallel mock joints 116. The mock joints 116 divide the upper surface 110 of the rooftile 100 so that it has the appearance of three side-by-side smaller rooftiles, mock rooftiles 101. The upper surface 110 of the roof tile 100 is divided width-wise into three portions of equal width (three mock tiles 101) by the longitudinally extending parallel mock joints 116. The cross-sectional profile of the mock joints is the same or similar to the profile of the joint formed between adjacent roof tile 100 when they are interconnected in a side-by-side arrangement The mock joint 116 has the shape of a channel, formed from opposing chamfered edges, that extends the length of the rooftiles 100 and has a lateral width W at the upper surface 110. Each mock joint 116 extends over the upper surface 110 of the roof tile and also down the front leading edge 102. The mock joints 116 therefore provide efficient drainage channels. In some example, but not necessarily all examples, there are nicks 114 at front leading edge 102 where the mock joint 116 extends from the upper surface 110 to the front edge 102. The upper surface 110 of the rooftile 100 has four blind holes 120. A blind hole 120 is a hole that is partially but not entirely through the depth of the roof tile 110. Each blind hole 120 comprises an open cavity at the upper surface 110 but the cavity is sealed by a sealing portion 150 and does not extend to the lower surface 200. In use a roofing nail can be hammered through the blind hole to attach the roof tile 100 to a wooden batten. The blind hole 120 therefore indicates where a roofing nail should be positioned but is sealed preventing the ingress of water. The lower surface 200 comprises, for each blind hole 120, a sealing portion 150 that seals the blind hole 120. The sealing portion 150 is relatively thin compared to adjacent parts of the roof tile 100 and is positioned on the lower surface 200 opposite the respective blind hole 120 on the upper surface 110. In the example illustrated the blind hole 120 has a smaller area than the sealing portion 150. This allows a roofing nail to be easily hammered through the blind hole 120 at an angle. In the example illustrated the sealing portion 150 extends longitudinally further than the blind hole 120. This allows a roofing nail to be easily hammered through the blind hole 120 parallel to the lateral edges of the roof tile but at an angle to a normal (perpendicular vector) of the front face 110 of the roof tile. In the example illustrated each blind hole120 has a substantially circular area at the upper surface 110 and the sealing portion 150 has a substantially oval (elliptic) area at the lower surface 200 of the rooftile 100. The major axis of the oval / ellipse is parallel to the lateral edges 106, 108 of the roof tile 100 and perpendicular to the leading front edge 102 and the trailing back edge 104 of the roof tile 100. The minor axis of the oval / ellipse is a perpendicular to the lateral edges 106, 108 of the rooftile 100 and parallel to the leading front edge 102 and the trailing back edge 104 of the roof tile 100. In order to prevent crack propagation, the sealing portion 150 is surrounded, at the lower surface 200, by a reinforced area 152 that is substantially thicker than the sealing portion 150 at its interior. The reinforced area 152 can also be substantially thicker than the areas of the roof tile 100 at its exterior. The reinforced area 152 can therefore form an inscribing ridge that surrounds the sealing portion 150. The blind holes 120 provide improved wind and rain performance. The blind holes 120 are positioned parallel to the trailing edge, towards the trailing edge 104 so that they can be overlapped when the roof tiles are laid using a single lap configuration. The upper surface 110 has a number of features in addition to the blind holes 120 and the mock joints 116. The upper surface 110 of each mock tile 101 has a double cambered surface. The upper surface 110 has a longitudinal camber between the trailing back edge 104 and the leading front edge 102. This provides superior drainage performance. The upper surface 110 has three distinct and similar cambers for each of the three mock tiles 101. A first lateral camber is a camber between the side edge 108 and a first mock joint 116 nearest that edge 108; a second lateral camber is a camber between the first mock joint 116 and the second mock joint 116; a third lateral camber is a camber between the second the mock joint 116 nearest the side edge 106 and the side edge 106. The term camber is used to connote a lightly convex shape. The deviation is a deviation out of a canonical flat plane parallel to the longitudinal and lateral dimensions of the rooftile (i.e. parallel to the parallel side edges 106, 108 and the parallel leading and trailing edges 102, 104) The curvature in the longitudinal direction when measured as a deviation perpendicular to the canonical plane (i.e. perpendicular to the longitudinal and lateral dimensions) can be less than 5% or in some cases less than 3%. The height difference between a, longitudinally separated, highest relief point and lowest relief point is expressed as a % of the horizontal separation between those points. The curvature in the lateral direction when measured as a deviation perpendicular to the canonical plane (i.e. perpendicular to the longitudinal and lateral dimensions) can be less than 5% or in some cases less than 3%. The height difference between, laterally separated, highest relief point and lowest relief point is expressed as a % of the horizontal separation between those points. The double camber creates a high point on the upper surface 110 of the roof tile 100 and the shadowing from light falling across the front leading edge accentuates the appearance of the individual mock tiles 101 appearance across the whole roof elevation. The side interlock 300 is formed by co-operation of a lower side-interlock (an underlock 300_1) of one roof tile and an upper side-interlock (overlock 300_2) of another rooftile. The underlock 300_1 of the rooftile 100 underlays an overlock 300_2 of a first side-by-side adjacent roof tile and the overlock 300_2 of the roof tile 100 overlays an underlock 300_1 of a different second side-by-side adjacent rooftile. The underlock 300-1 is at the side edge 108. The overlock 300-1 is at the side edge 106. The lower surface of the underlock 300_1 forms part of the under surface 200 of the roof tile 100. The upper surface of the overlock 300_2 forms part of the upper surface 110 of the rooftile 100. The underlock 300_1 comprises an edge protruding retainer 310 and a channel 312 formed between the edge protruding retainer 310 and the edge of the upper surface 110 of the rooftile 100. The edge protruding retainer 310 extends upwardly in a direction from the lower surface 200 to the front surface 110 of the roof tile 100. The underlock 300_1 extends for a substantial portion of a length of the roof tile 110. The edge protruding retainer 310 and the channel 312 extend in parallel for a 8 substantial portion of a length of the roof tile 110 parallel to the edges 106, 108 of the roof tile 100. The overlock 300_2 comprises an edge protruding retainer 320 and a channel 322 formed between the edge protruding retainer 320 and the edge of the lower surface 200 of the rooftile 100. The edge protruding retainer 320 extends downwardly in a direction from the upper surface 110 to the lower surface 200 of the roof tile 100. The overlock 300_2 extends for a substantial portion of a length of the roof tile 110. The edge protruding retainer 320 and the channel 322 extend in parallel for a substantial portion of a length of the roof tile 110 parallel to the edges 106, 108 of the roof tile 100. In use, at the overlock 300_2, the edge protruding retainer 310 of the overlock 300_2 is retained by the channel 312 of the underlock 300_1 of a first adjacent roof tile 100 and channel 320 of the overlock 300_2 retains the edge protruding retainer 310 of the underlock 300_1 of the first adjacent roof tile 100. In use, at the underlock 300_1, the edge protruding retainer 310 of the underlock 300_1 is retained by the channel 320 of the overlock 300_2 of a second adjacent roof tile 100 and the channel 312 of the underlock 300_1 retains the edge protruding retainer 320 of the overlock 300_2 of the second adjacent rooftile 100. The engagement of the overlock 300_2 with and underlock 300_1 of an adjacent roof tile prevents lateral relative movement between the tiles. The engagement of the underlock 300_1 with an overlock 300_2 of another adjacent roof tile prevents lateral relative movement between the tiles. A trailing portion of the underlock 300_1 comprises a cut-out portion 302. The underlock 300_1 does not extend to the trailing edge 104 of the roof tile 100 but stops short of the rear trailing edge 104 such that there is a gap adjacent the trailing portion of the underlock 300_1. A leading portion of the underlock 300_1 comprises a cut-out portion 304. The underlock 300_2 does not extend to the front leading edge 102 of the roof tile 100 but stops short of the front leading edge 102 such that there is a gap adjacent the front leading portion of the underlock 300_1. The cut-out portions 302 is sized and positioned so that it will be overlapped by an underlock 300_1 of an upslope rooftile 100 in use. The cut-out portions 304 is sized and positioned so that it will overlap an underlock 300_1 of a downslope rooftile 100 in use. The cut-out portions 302 forms a mortise (cavity) that receives a tenon (protrusion 402) of a side-by-side adjacent rooftile. The abutting interaction of the cut-out portions 302 and the side-by-side adjacent roof tile prevents movement of the roof tile 100 down slope relative to the adjacent side-by-side rooftile. The cut-out portions 304 forms a mortise (cavity) that receives a tenon (protrusion 404) of the side-by-side adjacent rooftile. The interaction of the cut-out portions 304 and the side-by-side adjacent rooftile prevents movement of the rooftile 100 up slope relative to the adjacent side-by-side roof tile. The cut-out portions 302 and the cut-out portions 304 therefor provide a longitudinal individual tile aesthetic with the interlock 300 being hidden between adjacent roof tiles 100. The cut-out 304 additionally enables concealment of the interlock 300_1,300_2 from view at the front leading edge 102 of the roof tile 100. The rooftile 100 has a discontinuous hanging nib comprising hanging nibs 130 separated by gaps 132. The nibs 130 are features on the lower surface 200 of the roof tile 200. The nibs 130 are located at the back trailing edge 104 of the roof tile 100. The nibs 130 extend downwardly from upper surface 100 to the lower surface 200 and provide integrated batten supports. This allows hanging of the roof tile 100 on a batten. The discontinuous form of the nibs 130 aids manufacturing to enable handling and removing the formed roof tile 100 from a mould. In the examples illustrated, there are 4 nibs 130 flush with the back trailing edge 104. There are three gaps 132 between the nibs 130. The nibs 130 do not extend under the underlock 300_1 or the overlock 300_2 A central gap 132 is aligned with a central support 140 on the lower surface 200. The central support 140 is positioned midway between three mock tiles 101 on the lower surface 200 of the roof tile 100. The central support 140 supports a central portion of the central mock tile 101. The central support 140 extends at least partially along the length of the rooftile 100. It provides a mid-span support. The central support 140 does not extend to the front leading edge 102. The lower surface 200 has substantially thinner portions adjacent the central support 140 to reduce weight. The lower surface 200 near the front leading edge comprises a weather bar 160 that extends substantially the width of the roof tile 100. The weather bar inhibits the ingress of wind-driven rain. In at least some examples the lower surface 200 at the overlock 300_2 comprises a clip recess 330 for retaining a roof tile clip. In some examples (Fig 9-11), the underlock 300_1 comprises an edge protruding retainer 310, an intermediate protruding retainer 314, an outer channel 312 formed adjacent the edge protruding retainer 310 between the edge protruding retainer 310 and the intermediate protruding retainer 314 and an inner channel 316 between the intermediate protruding retainer 314 and the edge of the upper surface 110 of the rooftile 100. The edge protruding retainer 310 extends upwardly in a direction from the lower surface 200 to the upper surface 110 of the roof tile 100. The intermediate protruding retainer 310 extends upwardly in the same direction. The underlock 300_1 extends for a substantial portion of a length of the roof tile 110. The protruding retainers 310, 314 and the channels 312, 316 extend in parallel for a substantial portion of a length of the roof tile 110 parallel to the edges 106, 108 of the roof tile 100. The overlock 300_2 comprises an edge protruding retainer 320, an intermediate protruding retainer 324, an outer channel 322 formed between the edge protruding retainer 320 and the intermediate protruding retainer 324 and an inner channel 326 formed between the intermediate protruding retainer 324 and the edge of the lower surface 200 of the rooftile 100. The protruding retainers 320, 324 extend downwardly in a direction from the upper surface 110 towards the lower surface 200 of the roof tile 100. The overlock 300_2 extends for a substantial portion of a length of the roof tile 110. The protruding retainers 320, 324 and the channels 322, 326 extend in parallel fora substantial portion of a length of the roof tile 110 parallel to the edges 106, 108 of the roof tile 100. In use, the overlock 300_2 of the rooftile 100 engages an underlock 300_1 of a first side-by-side adjacent roof tile. The edge protruding retainer 320 of the overlock 300_2 of the rooftile 100 is retained by the inner channel 316 of the underlock 300_1 of the first adjacent roof tile 100, the intermediate protruding retainer 324 of the overlock 300_2 is retained by the outer channel 312 of the underlock 300_1 of the first adjacent roof tile; the outer channel 322 of the overlock 300_2 retains the intermediate protruding retainer 314 of the underlock 300_1 of the first adjacent roof tile 100 and the inner channel 326 of the overlock 300_2 retains the edge protruding retainer 310 of the underlock 300_1 of the first adjacent roof tile. In use, at the underlock 300_1 of the roof tile 100 engages an overlock 300_2 of a second side-by-side adjacent rooftile. The edge protruding retainer 310 of the underlock 300_1 of the roof tile 100 is retained by the inner channel 326 of the overlock 300_2 of the second adjacent roof tile 100, the intermediate protruding retainer 314 of the underlock 300_1 is retained by the outer channel 322 of the overlock 300_2 of the second adjacent roof tile; the outer channel 312 of the underlock 300_1 retains the intermediate protruding retainer 324 of the overlock 300_2 of the second adjacent roof tile and the inner channel 316 of the underlock 300_1 retains the edge protruding retainer 320 of the overlock 300_2 of the second adjacent roof tile. The engagement of the overlock 300_2 with and underlock 300_1 of an adjacent roof tile prevents lateral relative movement between the tiles. The engagement of the underlock 300_1 with an overlock 300_2 of another adjacent roof tile prevents lateral relative movement between the tiles. In some but not necessarily all examples, the lower surface 200 of the roof tile 100 comprises one or more features 332 for preventing or reducing ingress of water. For example a vortex check feature 332 provides a shunt resistance which provides air and reduces capillary wicking. The vortex check feature 332 provides a break in the channel where air turbulence can interrupt the capillary action of the interlock 300. The roof tile 100 can be formed by various different methods. In some examples, a cementitious mixture such as concrete is provided from a hopper onto a multi-tile mould travelling underneath the hopper. A compression means such as a roller and / or slipper is used to compress the mixture into the multifile mould. The compression means forms the upper surface 110 of the roof tiles 100 and the mould is shaped to form the lower surface 200 of the roof tiles 100. The moulded, shaped mixture is cured and then the rooftiles 100 are removed from the moulds for stacking. The lower surface 200 of the roof tile 100 whilst contoured has detailing that keeps the key loadbearing elements, including the lower surface of the central support 140, in the same flat plane. The upper surface 110 of each mock tile has a centrally flattened section 111 between lateral cambers to the mock tile edges that provides increased alignment and greater surface area for the transfer of load when roof tiles are stacked one on top of the other. It should be appreciated that although certain functional features have been described, there is considerable freedom for a designer to implement these features in different physical forms. The description of a technical function with respect to a particularly illustrated feature, indicates that the particularly illustrated feature is capable to performing the technical function but is not indicative that the particularly illustrated feature is the only way of performing the technical function FIG 16A illustrates a first rooftile 100_1, a second rooftile 100_2 and a third rooftile 100_3. The first roof tile 100_1, second roof tile 100_2 and the third roof tile 100_3 are substantially the same. For example, the first roof tile 100_1, second roof tile 100_2 and third roof tile 100_3 can be as illustrated in FIGs 1 to 8 (first embodiment). For example, the first rooftile 100_1, second rooftile 100_2 and third rooftile 100_3 can be as illustrated in FIGs 9 to 11 (second embodiment). For example, the first roof tile 100_1, second rooftile 100_2 and third rooftile 100_3 can be as illustrated in FIGs 12-15 (third embodiment). The second rooftile 102_2 is side-by-side adjacent the first roof tile 100_1 and the third roof tile 100_3 is side-by-side adjacent the second rooftile 100_2. The overlock 300_2 of the first rooftile 100_1, the second rooftile 100_2 and the third roof tile 100_3 comprises a lengthwise extending channel. The underlock 300_1 of the first roof tile 100_1, the second roof tile 100_2 and the third roof tile 100-3 comprises a lengthwise extending protrusion. The lengthwise extending protrusion of the underlock 300_1 of the second roof tile 100_2 engages the lengthwise extending channel of the overlock 200_2 of the first rooftile 100_1. The lengthwise extending channel of the overlock 300_2 of the second rooftile 100_2 engages the lengthwise extending protrusion of the underlock 300_1 of the third rooftile 100_3. A cut-out 304 at a leading portion of the underlock 300_1 of the second roof tile 100_2 is sized to receive a protrusion 404 at a leading portion of an overlock 300_2 of the first roof tile 100_1. A cut-out 302 at a trailing portion of the underlock 300_1 of the second tile 100_2 is sized to receive a protrusion 402 at a trailing portion of the overlock 300_2 of the first tile 100_1. A cut-out 304 at a leading portion of the underlock 300_1 of the third rooftile 100_3 is sized to receive a protrusion 404 at a leading portion of an overlock 300_2 of the second rooftile 100_2. A cut-out 302 at a trailing portion of the underlock 300_1 of the third roof tile 100_3 is sized to receive a protrusion 402 at a trailing portion of the overlock 300_2 of the second rooftile 100_2. The upper surface 110 of the first roof tile 100_1, the second roof tile 100_2 and the third roof tile 100_3 are chamfered at the first lateral side edge and the second lateral side edge. The joint between the first roof tile 100_1 and the second roof tile 100_2 forms a channel with chamfered edges having a first cross-sectional profile. The joint between the second rooftile 100_2 and the third rooftile 100_3 forms a channel with chamfered edges having the first cross-sectional profile. The mock joints 116 of the first roof tile 100_1, the second roof tile 100_2 and the third roof tile 100_3 are channels comprising parallel chamfered edges and having the first cross-sectional profile. The preceding paragraphs describe a single lap rooftile 100 comprising: a front leading edge 102; a rear trailing edge 104; a first lateral side 108; a second lateral side 106; an upper surface 110 that is exposed when the rooftile 100 is fitted, wherein the upper surface 110 of the rooftile 100 has a pair of longitudinally extending parallel mock joints 116 that divide the upper surface 110 of the rooftile 100 width-wise so that the upper surface 110 of the roof tile has an appearance of three side-by-side mock rooftiles 101; a lower surface 200 that is hidden when the roof tile 100 is fitted. The roof tile 100 can comprise an underlock 300_1 associated with the first lateral side 108 and a overlock 300_2 associated with the second lateral side 106 wherein the underlock 300-1 and overlock 300-2 are correspondingly shaped for interlocking engagement. In at least some examples, the lower surface 200 comprises a central mid-span support 140 positioned midway between the three mock tiles 101 such that it supports a central portion of a central mock tile 101, wherein the central support 140 extends at least partially along the length of the roof tile 100 but does not extend to the front leading edge 102. In at least some examples, the lower surface 200 is divided into two sections by the central mid-span support 140 whereas the upper surface 110 is divided into three mock rooftiles 101 by the mock joints 116. The two sections can comprise lower thick ness areas compared to the central mid-span support 140. In at least some examples, the lower surface 200 has a form and appearance of a lower surface of a flat roof tile and the upper surface 110 has the form and appearance of three side-by-side mock plain double-lap rooftiles 10. In at least some examples, the upper surface 110 corresponding to each mock tile 101 has a lateral camber In at least some examples, the upper surface 110 corresponding to each mock tile 101 has a central flat supporting surface 111 and a lateral camber to the first lateral side 108 and a lateral camber to the second lateral side 106. The Central flat supporting surface 11 provides a flat surface for stacking the roof tiles 100 one on top of the other. In at least some examples, the rooftile 100 comprises a discontinuous hanging nib 130 comprising hanging nibs 130 separated by gaps 132, wherein the nibs 130 provide integrated batten supports. The discontinuous nibs 130 enable the provision of deeper nibs 130 per unit mass and therefore provide excellent on roof stacking without excessive mass. In at least some examples the nibs 130 are located at the back trailing edge 104 of the roof tile 100 and extend downwardly from the upper surface 110 to the lower surface 200 In at least some example, the nibs 130 do not extend under the underlock 300_1 or the overlock 300_2. In at least some examples, each mock joint 116 extends down the front leading edge 102 to provide a drainage channel. In at least some examples, the underlock 300_1 and overlock 300_2 are correspondingly shaped for interlocking engagement and preventing, in use, movement of the single lap roof tile 100 relative to a side-by-side adjacent tile laterally, upslope and downslope. In some but not necessarily all examples, the upper surface 110 of each mock tile 101 has the same double cambered surface comprising a longitudinal camber between the trailing back edge 104 and the leading front edge 102 and a lateral camber In some but not necessarily all examples, the upper surface 110 of the roof tile 100 has multiple blind holes, positioned towards the trailing edge 104, wherein each blind hole comprises an open cavity at the upper surface 110 that is sealed by a sealing portion 150 at the lower surface 200, wherein the sealing portion 150 that seals the blind hole 120 is relatively thin compared to adjacent parts of the roof tile 100, wherein each blind hole 120 has a smaller area than the corresponding sealing portion 150 and wherein each sealing portion 150 is surrounded, at the lower surface 200, by a reinforced area 152 that is substantially thicker than the sealing portion 150. In some but not necessarily all examples, the sealing portion 150 extends longitudinally further than the blind hole 120. In some but not necessarily all examples, the blind hole 120 has a substantially circular area at the upper surface 110 and the sealing portion 150 has a substantially oval area at the lower surface 200 of the roof tile 100. In some but not necessarily all examples, a major axis of the oval is parallel to the lateral edges 106, 108 of the roof tile and perpendicular to the leading front edge 102 and the trailing back edge 104 of the rooftile 100. In some but not necessarily all examples, there are four nibs separated by three gaps, and a central gap is aligned with a central mid-span support positioned midway between the three mock tiles 101 such that it supports a central portion of a central mock tile 101, wherein the central support 140 extends at least partially along the length of the roof tile 100 but does not extend to the front leading edge 102. In some but not necessarily all examples, the lower surface 200 has substantially thinner portions adjacent the central support 140. In some but not necessarily all examples, the underlock comprises a lengthwise extending protrusion for engagement of lengthwise extending channel of an overlock of an adjacent rooftile and the overlock comprises a lengthwise extending channel for engagement of lengthwise extending protrusion of underlock of an adjacent roof tile, wherein the lengthwise extending protrusion of the underlock and the lengthwise extending channel of the overlock prevent, in use, movement of the rooftile relative laterally across a roof slope, wherein a cut-out at a leading portion of the underlock is sized to receive a protrusion at a leading portion of an overlock of another roof tile to prevent, in use, movement of the roof tile relative to the another roof tile down slope of a roof and wherein a cut-out at a trailing portion of the underlock is sized to receive a protrusion at a trailing portion of the overlock of another roof tile to prevent, in use, movement of the roof tile relative to the another roof tile upslope of a roof. In some but not necessarily all examples the upper surface 110 is chamfered at the first lateral side edge and the second lateral side edge, where the mock joints are channels comprising parallel chamfered edges. In some but not necessarily all examples there is provided a roofing system comprising a first roof tile 100_1; a second rooftile 100-2; a third rooftile 100_3; wherein the second roof tile is side-by-side adjacent the first tile and the third tile is side-by-side adjacent the second tile, wherein the overlock of the first roof tile, the second roof tile and the third roof tile comprises a lengthwise extending channel; and wherein the underlock of the first roof tile, the second roof tile and the third roof tile comprises a lengthwise extending channel; wherein the lengthwise extending protrusion of the underlock of the second tile engages the lengthwise extending channel of the overlock of the first tile wherein the lengthwise extending channel of the overlock of the second tile engages the lengthwise extending protrusion of the underlock of the third tile, wherein a cut-out at a leading portion of the underlock of the second tile is sized to receive a protrusion at a leading portion of an overlock of the first roof tile wherein a cut-out at a trailing portion of the underlock of the second tile is sized to receive a protrusion at a trailing portion of the overlock of the first tile wherein a cut-out at a leading portion of the underlock of the third tile is sized to receive a protrusion at a leading portion of an overlock of the second rooftile wherein a cut-out at a trailing portion of the underlock of the third tile is sized to receive a protrusion at a trailing portion of the overlock of the second roof tile. In some but not necessarily all examples of the system, the upper surface 110 od the first roof tile, the second roof tile and the third roof tile are chamfered at the first lateral side edge and the second lateral side edge wherein the joint between the first tile and the second tile forms a channel with chamfered edges having a first cross-sectional profile wherein the joint between the second tile and the third tile forms a channel with chamfered edges having the first cross-sectional profile wherein the mock joints of the first roof tile, the second roof tile and the third roof tile are channels comprising parallel chamfered edges and having the first cross-sectional profile. In some but not necessarily all examples, there is provided a single lap roof tile comprising: a front leading edge; a rear trailing edge; a first lateral side; a second lateral side; an upper surface 110 that is exposed when the rooftile 100 is fitted, wherein the upper surface 110 of the rooftile 100 has a pair of longitudinally extending parallel mock joints 116 that divide the upper surface 110 of the rooftile 100 width-wise so that the upper surface 110 of the roof tile has an appearance of three side-by-side mock rooftiles 101, a lower surface 200 that is hidden when the roof tile 100 is fitted; a discontinuous hanging nib comprising hanging nibs 130 separated by gaps 132, wherein the nibs 130 provide integrated batten supports. In some but not necessarily all examples the nibs 130 are located at the back trailing edge 104 of the roof tile 100 and extend downwardly from the upper surface 110 to the lower surface 200 and provide integrated batten supports. In some but not necessarily all examples there is provided a single lap roof tile comprising: a front leading edge; a rear trailing edge; a first lateral side; a second lateral side; an upper surface 110 that is exposed when the rooftile 100 is fitted, wherein the upper surface 110 of the rooftile 100 has a pair of longitudinally extending parallel mock joints 116 that divide the upper surface 110 of the rooftile 100 width-wise so that the upper surface 110 of the roof tile has an appearance of three side-by-side mock roof tiles 101, wherein each mock joint 116 extends down the front leading edge 102 to provide a drainage channel; a lower surface 200 that is hidden when the roof tile 100 is fitted; an underlock associated with the first lateral side and a overlock associated with the second lateral side wherein the underlock and overlock are correspondingly shaped for interlocking engagement and preventing, in use, movement of the single lap roof tile relative to a side-by-side adjacent tile laterally, upslope and downslope; a discontinuous hanging nib comprising hanging nibs 130 separated by gaps 132, wherein the nibs 130 are located at the back trailing edge 104 of the roof tile 100 and extend downwardly from the upper surface 110 to the lower surface 200 and provide integrated batten supports, wherein the nibs do not extend under the underlock 300_1 or the overlock 300_2. Previously there was a choice to be made between plain tile which are laid double lapped and interlocking tiles that require only a single lap. The rooftile tile 100 provides advantages of both the plain tile and the interlocking tile. The rooftile 100 provides three mock plain tiles 101 on the upper surface that are carried by a single interlocking tile. The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use ‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to “comprising only one...” or by using “consisting”. In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ‘example’ or ‘for example’ or ‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus ‘example’, ‘for example’, ‘can’ or ‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example. Although examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims. Features described in the preceding description may be used in combinations other than the combinations explicitly described above. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not. The term ‘a’, ‘an’ or ‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a / an / the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use ‘a’, ‘an’ or ‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or ‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning. The presence of a feature (or combination of features) in a claim is a reference to that feature or (combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result. In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described. The above description describes some examples of the present disclosure however those of ordinary skill in the art will be aware of possible alternative structures and method features which offer equivalent functionality to the specific examples of such structures and features described herein above and which for the sake of brevity and clarity have been omitted from the above description. Nonetheless, the above description should be read as implicitly including reference to such alternative structures and method features which provide equivalent functionality unless such alternative structures or method features are explicitly excluded in the above description of the examples of the present disclosure. Whilst endeavouring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not emphasis has been placed thereon. l / we claim:

Claims

1. A single lap rooftile comprising:a front leading edge;a rear trailing edge;a first lateral side;a second lateral side;an upper surface that is exposed when the roof tile is fitted, wherein the upper surface of the rooftile has a pair of longitudinally extending parallel mock joints that divide the upper surface of the roof tile width-wise so that the upper surface of the roof tile has an appearance of three side-by-side mock roof tiles,a lower surface that is hidden when the roof tile is fitted;a discontinuous hanging nib comprising hanging nibs separated by gaps, wherein the nibs provide integrated batten supports.

2. A roof tile as claimed in claim 1, wherein the nibs are located at the back trailing edge of the roof tile and extend downwardly from the upper surface to the lower surface.

3. A roof tile as claimed in claim 1 or 2, wherein the nibs do not extend under the underlock or the overlock.

4. A roof tile as claimed in any preceding claim, wherein each mock joint extends down the front leading edge to provide a drainage channel.

5. A roof tile as claimed in any preceding claim, wherein the underlock and overlock are correspondingly shaped for interlocking engagement and preventing, in use, movement of the single lap roof tile relative to a side-by-side adjacent tile laterally, upslope and downslope.

6. A roof tile as claimed in any preceding claim, wherein the upper surface of each mock tile has a lateral camber.

7. A roof tile as claimed in any preceding claim, wherein the upper surface of each mock tile has a central flat supporting surface and a lateral camber to the first lateral side and a lateral camber to the second lateral side.

8. A roof tile as claimed in any preceding claim, wherein the upper surface of each mock tile has the same double cambered surface comprising a longitudinal camber between the trailing back edge and the leading front edge and a lateral camber.

9. A roof tile as claimed in any preceding claim, wherein the upper surface of the roof tile has multiple blind holes, positioned towards the trailing edge, wherein each blind hole comprises an open cavity at the upper surface that is sealed by a sealing portion at the lower surface, wherein the sealing portion that seals the blind hole is relatively thin compared to adjacent parts of the roof tile, wherein each blind hole has a smaller area than the corresponding sealing portion and wherein each sealing portion is surrounded, at the lower surface, by a reinforced area that is substantially thicker than the sealing portion.

10. A rooftile as claimed in claim 9, wherein the sealing portion extends longitudinally further than the blind hole.

11. A roof tile as claimed in claim 9 or 10, wherein the blind hole has a substantially circular area at the upper surface and the sealing portion has a substantially oval area at the lower surface of the roof tile.

12. A rooftile as claimed in claim 1, wherein a major axis of the oval is parallel to the lateral edges, of the roof tile and perpendicular to the leading front edge and the trailing back edge of the roof tile.

13. A rooftile as claimed in any preceding claim wherein there are four nibs separated by three gaps, and a central gap is aligned with a central mid-span support positioned midway between the three mock tiles such that it supports a central portion of a central mock tile, wherein the central support extends at least partially along the length of the roof tile but does not extend to the front leading edge.

14. A rooftile as claimed in claim 13, wherein the lower surface has substantially thinner portions adjacent the central support.

15. A roof tile as claimed in any preceding claim wherein the underlock comprises a lengthwise extending protrusion for engagement of lengthwise extending channel of an overlock of an adjacent roof tile and the overlock comprises a lengthwise extending channel for engagement of lengthwise extending protrusion of underlock of an adjacent rooftile, wherein the lengthwise extending protrusion of the underlock and the lengthwise extending channel of the overlock prevent, in use, movement of the roof tile relative laterally across a roof slope, wherein a cut-out at a leading portion of the underlock is sized to receive a protrusion at a leading portion of an overlock of another roof tile to prevent, in use, movement of the roof tile relative to the another roof tile down slope of a roof and wherein a cut-out at a trailing portion of the underlock is sized to receive a protrusion at a trailing portion of the overlock of another roof tile to prevent, in use, movement of the roof tile relative to the another roof tile upslope of a roof.

16. A rooftile as claimed in any preceding claim, wherein the upper surface is chamfered at the first lateral side edge and the second lateral side edge, where the mock joints are channels comprising parallel chamfered edges.

17. A roof tile as claimed in any preceding claim, wherein the lower surface that is hidden when the roof tile is fitted comprises a central mid-span support positioned midway between the three mock tiles such that it supports a central portion of a central mock tile, wherein the central support extends at least partially along the length of the roof tile but does not extend to the front leading edge.

18. A rooftile as claimed in claim 17, wherein the lower surface is divided into two sections by the central mid-span support whereas the upper surface is divided into three mock roof tiles by the mock joints.

19. A roofing system comprisinga first rooftile as claimed in any preceding claim;a second rooftile as claimed in any preceding claim;a third roof tile as claimed in any preceding claim;wherein the second roof tile is side-by-side adjacent the first tile and the third tile is side-by-side adjacent the second tile, wherein the overlock of the first roof tile, the second roof tile and the third roof tile comprises a lengthwise extending channel;and wherein the underlock of the first roof tile, the second roof tile and the third roof tile comprises a lengthwise extending channel;wherein the lengthwise extending protrusion of the underlock of the second tile engages the lengthwise extending channel of the overlock of the first tile, wherein the lengthwise extending channel of the overlock of the second tile engages the lengthwise extending protrusion of the underlock of the third tile, wherein a cut-out at a leading portion of the underlock of the second tile is sized to receive a protrusion at a leading portion of an overlock of the first roof tile, wherein a cut-out at a trailing portion of the underlock of the second tile is sized to receive a protrusion at a trailing portion of the overlock of the first tile, wherein a cut-out at a leading portion of the underlock of the third tile is sized to receive a protrusion at a leading portion of an overlock of the second roof tile, wherein a cut-out at a trailing portion of the underlock of the third tile is sized to receive a protrusion at a trailing portion of the overlock of the second roof tile.

20. A roofing system as claimed in claim 19 wherein the upper surface of the first roof tile, the second roof tile and the third rooftile are chamfered at the first lateral side edge and the second lateral side edgewherein the joint between the first tile and the second tile forms a channel with chamfered edges having a first cross-sectional profilewherein the joint between the second tile and the third tile forms a channel with chamfered edges having the first cross-sectional profilewherein the mock joints of the first roof tile, the second roof tile and the third roof tile arechannels comprising parallel chamfered edges and having the first cross-sectional profile.

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