5 The present invention relates to a roof for a building that includes a plurality of roof cladding sheets, typically metal roof cladding sheets, and a roof frame that supports the roof cladding sheets.

The present invention also relates to a roof cladding sheet for a building.

The present invention also relates to an under flashing sheet and other elements o that contribute to waterproofing a building

The present invention also relates to a method of installing a roof on a building.

The present invention also relates to a solar roof panel assembly that includes a roof cladding sheet and a solar roof panel, which may be a solar (PV) roof panel, for converting solar energy into another form of energy, such as electrical energy, mounted5 on the roof cladding sheet.

BACKGROUND ART

The roofing market in Australia is dominated by roof tiles made from terracotta 0 or concrete materials and metal roof cladding sheets that are roll-formed or pressed from steel strip.

The roofing market is extremely cost sensitive.

There is significant competition between the roof tile segment and the metal roof cladding sheet segment of the market.

5 There is also significant competition between the participants in each segment.

For example, there is significant competition for market share amongst manufacturers of roof tiles within this segment of the market. There is also significant competition for market share amongst manufacturers of metal roof cladding sheets within this segment of the market.

o Traditionally, metal roof cladding sheets for a residential building are custom- cut to a length required to cover a distance from an eave to a ridge of a roof of the building. This arrangement is often described as a "vertical" arrangement of roof cladding sheets on a roof. This arrangement eliminates a number of joins in the metal roof cladding sheets, particularly along the sheet length. This is important from installation and weatherproofing perspectives. However, custom-cutting sheets to length can have an impact on cost.

There are proposals in the patent and the non-patent literature to use metal roof cladding sheets that extend horizontally across a roof. This alternative arrangement of metal roof cladding sheets on a roof has potential advantages over the above-described vertical arrangement of metal roof cladding sheets. However, the applicant has realised that there are a number of technical hurdles associated with horizontal metal roof cladding sheet systems. These technical hurdles include, by way of example, forming a roof that meets structural requirements and is waterproof.

The above description should not be taken to be an admission of the common general knowledge in Australia or elsewhere. SUMMARY OF THE DISCLOSURE

The present invention provides a roof for a building that includes a roof frame having a plurality of spaced-apart roof trusses extending between a ridge and a gutter of the roof and a plurality of roof cladding sheets, typically metal roof cladding sheets, fixed directly from a structural viewpoint to the trusses so that there is a direct structural connection between the roof cladding sheets and the roof frame, with the roof cladding sheets extending horizontally across the roof frame, and with the roof being a structural roof cladding as described herein.

The roof may be of any shape. The roof may include one or more than one valley, hip and barge board section.

The term "trusses" as used herein is understood to include structures described as truss frames, rafters or other construction elements that extend between the ridge and the gutter of the roof.

The above-described roof includes a direct structural connection between the roof cladding sheets and the roof frame. This means that there are no structural elements between the roof cladding sheets and the trusses. For example, the roof frame does not include (and does not need) horizontally extending battens secured to the trusses and on which the roof cladding sheets are secured that are often required for typical roof construction. By way of further example, the roof frame does not include (and does not need) plywood or other sheet material secured to the trusses and on which the roof cladding sheets are secured that are often required for typical roof construction. 5 Roof installation is a significant component of the cost of roofs. Securing

structural metal roof cladding sheets directly to roof trusses provides an opportunity to significantly simplify installation cost (and installation time) of roof cladding sheets on roof frames. The invention is not confined to roofs having solar roof panels and extends to roofing generally. The invention also makes it possible to manufacture metal 0 roof cladding sheets as "modular" lengths, which can be packed in bundles of any

transportable number of sheets, typically 50 sheets or more, and conveniently transported to building sites from distribution centres (which may be roll forming centres). This procedure makes it possible to move away from the current procedure of customising roof installations - i.e. a skilled person measuring a roof, determining the 5 size and numbers of metal roof cladding sheets required for that roof, a roll former producing the customised lengths of sheets, with the sheets being transported to site and installed. A move to "modular" roof cladding sheets provides an opportunity for the applicant to reduce the installation cost of steel roof cladding sheets to an extent that there is an opportunity to increase market share significantly.

o Typical roof construction also relies on battens or timber supporting members

(often referred to as "valley boards") under the valley section flashing of the roof. The roof of the invention may include structural flashings so that it is not necessary to use supporting battens or valley boards when the roof includes valleys.

The roof of the invention may also include structural ridge and barge board 5 section flashings when the roof includes ridge and barge board sections.

The term "structural roof cladding" is understood herein to mean that the roof cladding formed from the roof frame and the roof cladding sheets secured directly to roof trusses at a given truss spacing can support the weight of a person walking on the roof without the roof cladding being damaged. It is also understood to mean that the o roof cladding will also withstand wind and other structural loading conditions imposed on the roof structure. There are a number of different factors that may contribute to forming a structural roof cladding. These factors include, by way of example only, the spacing of the trusses, forming the roof cladding sheet from a structural sheet material, appropriate gauge selection for the sheet, appropriate tensile strength selection for the steel or other material of the sheet, selection of the width and length of the sheet, and forming the sheet with reinforcing ribs and other formations that strengthen the sheet.

In a situation where the roof cladding sheets are metal roof cladding sheets, the roof cladding sheets may be made from a structural sheet as defined in Australian Standard AS 1562 Part 1 or 2.

The roof cladding sheets may be 1-9 m long.

The roof cladding sheets may be 0.3-1.0 m wide.

The roof cladding sheets may include at least two pans and reinforcing formations that separate the pans.

The pans may be at an angle of 2-15 degrees to a horizontal axis.

The width of the pans may be 10-25 cm.

The pans may have intermediate stiffening ribs to improve the aesthetics, increase structural rigidity or hide defects introduced in the forming such as oil- canning.

The reinforcing formations may be ribs.

The reinforcing formations may be angled sections (transitions) that separate the pans.

The reinforcing formations may be angled steps that separate the pans.

Typically, the steps are perpendicular or angled steps in relation to the pans.

The roof cladding sheets may be made (for example roll-formed or pressed) from steel sheet.

The tensile strength of the steel may be 300-900 MPa.

The gauge of the roof cladding sheets may be 0.3 -0.8 mm.

The roof cladding sheet may include a solar assembly mounted to the cladding sheet.

The roof cladding sheets may include an acoustic laminate mounted to the cladding sheet.

The roof cladding sheets may include a fire resistant laminate mounted to the cladding sheet. The roof cladding sheets may include side edge formations that enable a plurality of the sheets to be positioned side by side in abutting or overlapping relationship.

The roof cladding sheets may include a pair of parallel sides and an upturned side formation extending along one side and a downturned side formation extending along the other side.

The upturned side formation and the downturned side formation may be formed to enable a plurality of the sheets to be positioned horizontally side by side in overlapping relationship.

The upturned side formation and the downturned side formation are

advantageous in terms of facilitating mounting adjacent roof cladding sheets in overlapping relationship on the roof frame.

Typically, the first roof cladding sheets that are installed on the roof frame are the sheets adjacent a gutter of the roof, with the downturned side formation of each roof cladding sheet in a first line of sheets being positioned adjacent the gutter and the upturned side formation of each sheet being positioned on the roof frame away from the gutter. The upturned side formations of the sheets in this first line provide effective reference points for locating the next line of roof cladding sheets on the roof frame. Specifically, the downturned side formation of each roof cladding sheet in the next line of sheets is positioned to overlie the upturned side formations of the roof cladding sheets in the first line of sheets and thereby provide continuous coverage at the overlap. Hence, the upturned side formations of the roof cladding sheets in the first line of sheets cooperate with the downturned side formations of the roof cladding sheets in the next line of sheets to locate the next line of sheets on the roof frame.

The upturned side formations and the downturned side formations are also advantageous because installing roof cladding sheets on the roof frame with the downturned side formations of the sheets on the gutter line provides an opportunity, optionally in conjunction with suitable flashing (described herein as stater sheets), to close the roof at the gutter line and minimise the risk of ember entry into a roof space at the gutter line.

The roof cladding sheets may be a quadrilateral sheet. The roof cladding sheets may be a quadrilateral sheet with a pair of parallel sides and a pair of parallel ends.

The roof cladding sheets may be mounted directly to the roof frame by any suitable fastener systems.

5 Waterproofing roofs is an important issue for any roof. The applicant has

realised that waterproofing is a particularly significant technical issue for horizontally extending roof cladding sheets at the ends of the sheets at hips, valleys, and barge board sections of roofs, particularly in situations where rain sheets across roofs.

The roof of the invention may include weatherproofing in the form of an under o flashing sheet on any one of a hip, valley or barge board section of the roof that is

secured directly to the roof frame and is positioned so that ends of the roof cladding sheets that extend to the hip, valley or barge board section at least partially overlie the under flashing sheet.

The under flashing sheet may include an elongate channel or a plurality of

5 elongate channels extending along the sheet that receive water that flows along

horizontally-extending roof cladding sheets and discharges from the ends of the roof cladding sheets, with the channel or channels directing the water downwardly from the roof so that the water does not flow into a roof space between the building and the roof.

The under flashing sheet may include elongate ribs and troughs that define the o channel or channels. The use of ribs and troughs is advantageous in terms of making the under flashing sheet a structural element.

The under-flashing sheet may include a plurality of elongate ribs and troughs that define a plurality of parallel channels. With this arrangement, any water that is not contained within the first channel, i.e. the channel immediately adjacent the ends of the 5 roof cladding sheets, and spills from the first channel can be contained and directed from the roof in the second and any additional parallel channels.

The under flashing sheet may include ends having a 45 degree angle for hip and valley applications to avoid the need for on-site cutting of the sheet.

The under flashing sheet may be adapted for hip or valley sections of the roof. 0 By way of example, the under flashing sheet may be arcuate in transverse cross- section to fit the profile of the hip or valley sections of the roof.

The under flashing sheet may be adapted for a barge board section of the roof. By way of example, the under flashing sheet may include a downturned leg that is adapted to be positioned against the barge board section.

The design of the under flashing sheet may be such that one suitably-formed member may be used or adapted to fulfil the role of the hip and valley section under flashings.

The roof may include weatherproofing in the form of an over flashing sheet that is secured direcly to the roof frame and is positioned over an under flashing sheet and is formed to cover the ends of adjacent roof cladding sheets. The over flashing sheet provides a first stage waterproofing and the under flashing sheet provides a second stage wate roofϊng at the hips, valleys, and barge board sections of the roof.

The roof may include a flashing sheet, referred herein as a roof starter sheet, that is secured directly to the roof frame and is positioned between the gutter of the roof and a first line of roof cladding sheets adjacent the gutter line. The roof starter sheet provides a transition between the gutter and the first line of roof cladding sheets that may be an advantage in terms of the roof construction at the gutter of the roof. The roof starter sheet may also be an advantage in terms of water flow from the roof into the gutter. The roof starter sheet may also be an advantage in terms of minimising the risk of ember entry to the roof space.

The roof starter sheet may include a reinforcing rib extending along one side of the sheet. With this arrangement, the downturned side formation of each roof cladding sheet in the first line of roof cladding sheets overlies the reinforcing rib of the flashing sheet. This reinforcing rib can also provide a means of weather proofing to restrict any water that is carried under the first line of roof cladding sheets from entering the roof space.

The roof starter sheet may form an attachment location for the roof cladding sheets in the first line of roof cladding sheets.

The attachment location may be the reinforcing rib.

The roof may include non-structural elements, such as sarking, between the roof cladding sheets and the roof trusses.

The roof may have a pitch of 15-35 degrees.

The roof pitch may be 20-25 degrees.

The centre-centre spacing of the trusses of the roof frame may be 400-1300 mm. Typically, the centre-centre spacing of the trusses of the roof frame is 450-750 mm.

Typically, the average centre-centre spacing of the trusses of the roof frame is 600 mm.

Typically, the centre-centre spacing of the trusses of the roof frame is 550-650 mm.

The present invention also provides a roof for a building that includes a roof frame having a plurality of spaced-apart roof trusses extending between a ridge and a gutter of the roof and a plurality of horizontally-extending roof cladding sheets fixed directly from a structural viewpoint to the trusses so that there is a direct structural connection between the roof cladding sheets and the roof frame, and weathe roofing in the form of an under flashing sheet on any one of a hip, valley or barge board section of the roof that is secured directly to the roof frame and is positioned so that ends of the roof cladding sheets that extend to the hip, valley or barge board section at least partially overlie the under flashing sheet.

The under flashing sheet may include an elongate channel or a plurality of elongate channels extending along the sheet that receive water that flows along the horizontally-extending roof cladding sheets and discharges from the ends of the roof cladding sheets, with the channel or channels directing the water downwardly from the roof so that the water does not flow into a roof space between the building and the roof.

The present invention also provides a method of installing the above-described roof that includes the following steps:

(a) securing the above-described roof starter sheets to the roof frame;

(b) securing the above-described under flashing sheets to any hips, valleys and barge boards of the roof frame;

(c) securing a first line of the above-described roof cladding sheets to the roof frame, with the ends of the sheets extending at least partially across and thereby overlying the under flashing sheets at any hips, valleys and barge boards of the roof frame, whereby the overlap ensures that water flowing horizontally across the roof is discharged into the troughs of the flashing sheets; and

(d) repeating step (c) for each successive line of the above-described roof cladding sheets. The method may also include positioning over-flashing sheets to cover the under flashing sheets.

The present invention also provides a roof cladding sheet, typically a metal roof cladding sheet, as described above.

The present invention also provides a roof cladding sheet, typically a metal roof cladding sheet, that can form a structural roof cladding as described herein when directly mounted to roof trusses at centre-centre truss spacing of 400-1300 mm, typically 450-750 mm, and more typically an average of 600 mm.

The present invention also provides an under flashing sheet, typically a metal under flashing sheet, as described above.

The present invention also provides a roof starter sheet, typically a metal roof stater sheet, as described above.

The present invention also provides a solar roof panel assembly that includes the above-described roof cladding sheet and a solar roof panel, which may be a solar (PV) roof panel, for converting solar energy into another form of energy, such as electrical energy, mounted on the roof cladding sheet.

The term "solar roof panel" is understood herein to mean a panel that can convert solar energy into another form of energy, such as electrical or thermal energy, and can be mounted to a roof of a building. By way of example, one type of solar roof panel of interest to the applicant includes a photovoltaic cell module for converting solar energy into electrical energy.

The solar roof panel may include (a) a photovoltaic cell module for converting solar energy into electrical energy and (b) electrical components, such as a wiring junction box and electrical cables and other devices for transferring electrical energy from the solar roof panel for use in an electrical system of the building or a local electrical network.

The solar roof panel may be in the form of a flexible film.

The photovoltaic cell module may include a semi-conductor material electro- deposited or otherwise deposited on an electrically-conductive, such as stainless steel, flexible substrate and encapsulated in a moisture barrier laminate material.

The photovoltaic cell module may include organic photovoltaic material encapsulated in a moisture barrier laminate material. The photovoltaic cell module may include organic or semi-conductor material directly applied/deposited on the sheet and encapsulated in a moisture barrier laminate material.

The present invention also provides a system for generating electrical energy from solar energy using the solar roof panel mounted on the above-described roof cladding sheet.

The present invention addresses a number of the technical hurdles associated with horizontal roof cladding sheet systems, typically metal roof cladding systems, described in the patent and non-patent literature. In particular, although not exclusively, these technical hurdles include, by way of example, forming a roof that meets structural requirements and is waterproof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described further, by way of example only, with reference to the accompanying drawings of which:

Figure 1 is a top plan view of a roof of a building in accordance with one embodiment of the invention having a plurality of structural metal roof cladding sheets in accordance with one embodiment of the invention mounted to the roof frame, and with a section of the roof uncovered to show the roof frame in that section;

Figures 2 to 4 are perspective views of sections of the roof shown in Figure 1 at different locations and stages of the construction of the roof, illustrating how the roof cladding sheets and other roof components, such as starter sheets and under flashing sheets, and over flashing sheets, are positioned during roof construction;

Figure 5 is a perspective view of the embodiment of the structural metal roof cladding sheet of the roof of Figures 1 to 4;

Figure 6 is a transverse cross-section of the roof cladding sheet shown in Figure

5;

Figure 7 is a perspective view of an embodiment of a flashing sheet that can be used as an under flashing element for a section of a hip of the roof of Figures 1 to 4 or as an under flashing element for a section of a valley of the roof of Figures 1 to 4,

Figure 8 is a transverse cross-section of the flashing sheet shown in Figure 7; Figure 9 is a perspective view of an embodiment of a flashing sheet that can be used as an under flashing element of the barge board at the gable section of the roof of Figures 1 to 4;

Figure 10 is a transverse cross-section of the flashing sheet shown in Figure 9;

Figure 11 is a perspective view of an embodiment of a flashing sheet that can be used as a starter element at the gutter of the roof of Figures 1 to 4;

Figure 12 is a transverse cross-section of the flashing sheet shown in Figure 11;

Figure 13 is a perspective view that illustrates the position of one of the roof cladding sheets on one of the under flashing element for a section of a hip of the roof shown in Figures 1 to 4 during the construction of the roof; and

Figure 14 is a vertical sectional view at the gutter line of the roof of Figures 1 to 4 that illustrates another embodiment of a flashing sheet that can be used as a starter element of the roof of Figures 1 to 4.

DESCRIPTION OF AN EMBODIMENT

With reference to Figures 1 to 4, the roof in accordance with one embodiment of the invention includes:

(a) a roof frame,

(b) a plurality of roof cladding sheets 9 in accordance with one embodiment of the invention mounted directly to the roof frame;

(c) a gutter 7 extending around the perimeter of the roof, save for at the gable end 31 of the roof,

(d) a plurality of over flashing sheets 67 that cover the hips and the valley of the roof; and

(e) a plurality of roof starter sheets 11 that extend between the gutter 7 and a first roof cladding sheet 9 adjacent the gutter 7.

The roof also includes a plurality of under flashing sheets 69, 71 for the hips, valley, and barge board sections of the roof that are not shown in Figures 1 to 4 but are shown in Figures 7 to 10 and 13 and described further below. The roof is an L-shaped hip roof with one gable end 31. The roof has an reshaped ridge rafter 61, hip rafters 63, and a valley rafter 65. The invention is not limited to the specific roof shape shown in the Figures and extends to any roof design.

The roof frame includes a plurality of parallel upright A-frame assemblies. The A-frame assemblies include downwardly inclined spaced-apart trusses 17 extending between the ridge 61 and the gutter 7 of the roof. The trusses 17 are the structural connection points for the roof cladding sheets 9. The partial roof construction shown in Figure 1 reveals the location of the roof trusses 17. Typically, the roof trusses are an average of 600 mm centre-centre spacing.

The invention is not limited to the specific roof frame shown in the Figures and extends to any truss-based roof frame. In this context, the term roof truss also includes structures described as roof truss frames, rafters or other construction elements that extend between the ridge and the gutter of the roof.

The roof cladding sheets 9 are mounted (from a structural perspective) directly to the trusses 17 by any suitable fastening means, such as fasteners, adhesives and concealed clips.

There may be sarking, insulation blanket or other non-structural elements between the roof cladding sheets 9 and the roof trusses 17.

The roof cladding sheets 9 are made from a structural sheet as defined in Australian Standard AS 1562 Part 1 or 2. The disclosures in these parts of the

Australian Standard are incorporated herein by cross-reference.

The roof cladding sheets 9 are arranged to run horizontally across the roof.

The lengths of the roof cladding sheets 9 may be selected so that the sheets 9 run horizontally across the whole length of the roof sections between hips, valleys and barge board sections of the roof.

Alternatively, the lengths of the sheets 9 may be selected so that multiple lengths of the sheets 9 are required to cover a given span length or so that a modular section length is chosen to reduce stock holding.

With reference to Figures 5 and 6, each roof cladding sheet 9 is roll-formed or pressed from steel strip and is generally quadrilateral in shape and of any suitable length and width and includes:

(a) a pair of parallel sides 21 , (b) a pair of parallel ends 23,

(c) an upturned side formation 25 extending along one side 21,

(d) a downturned side formation 27 extending along the other side 21,

(e) a first pan section 29,

(f) a second pan section 33, and

(g) a step 35 that separates the pan sections 29, 33 and acts as a reinforcing element.

The pan sections 29, 33 are formed as planar pan sections and do not include any ribs or other formations that inhibit water flow across the pans. The invention is not limited to this arrangement and the pan sections 29, 33 may include ribs or other formations that strengthen the roof cladding sheets 9. These ribs or other formations may be positioned to have a secondary effect of inhibiting water flow.

The side formations 25, 27 also act as reinforcing elements and contribute to the overall structural properties of the roof cladding sheet 9.

In addition, the side formations 25, 27 are formed to facilitate positioning successive roof cladding sheets 9 in overlapping relationship while minimising back flow of water into the roof space. More specifically, the design of the side formations 25, 27 is such that an anti-capillary lap is formed to limit the ingress of water into the roof space.

The roof cladding formed from the roof cladding sheets 9 mounted to the roof trusses 17 provides a "structural" roof cladding on the roof at the spacing of the trusses 17. In other words, the roof cladding formed from the roof cladding sheets 9 secured directly to roof trusses 17 at the truss spacing can support the weight of persons walking on the roof without the roof cladding being damaged. The roof cladding sheets 9 can also withstand wind and other structural loads typically encounter by a roof. As is indicated above, there are a number of different factors that may contribute to forming a structural roof cladding and these factors include, by way of example only, forming the roof cladding sheet 9 from a structural sheet material, appropriate gauge selection for the sheet, appropriate tensile strength selection for the steel, selection of the width and length of the sheet, and forming the sheet with reinforcing ribs and other formations that strengthen the sheet.

The over flashing sheets 67 are formed from pressed strip and are provided as a first stage waterproofing on the hips of the roof. As is described further below, the under flashing sheets 69 which are positioned beneath and covered by the over flashing sheets 67 provide a second stage waterproofing on the roof hips. The over flashing sheets 67 may also be formed to contribute to the aesthetic appeal of the roof. As can be seen in Figure 4, the lower arrow-head end of each over flashing sheets 67 includes an end section that has a plurality of openings 107 that allow the discharge of water flowing downwardly along the under flashing sheets 69.

The roof starter sheets 11 are provided as a transition between the gutter 7 and the first line of roof cladding sheets adjacent the gutter 7.

With reference to Figures 11 and 12, each starter sheet 1 1 is an elongate element that is roll-formed or press-formed from steel strip and includes parallel sides 45 and parallel ends 47. The starter sheet 11 may be any suitable length and any suitable width. The starter sheet 1 1 includes a wide, flat central pan section 97, a slightly inclined lip 99 on the gutter-side, and an upwardly and inwardly curved lip 101 on the roof side. The lip 101 is formed as a barrier to water flow up the roof into the roof space.

The roof starter sheets 11 and the under flashing sheets 69, 71 for the hips, valley, and barge board sections of the roof that are shown in Figures 7 to 10 and 13 are also important structural elements of the invention that contribute to the "structural" roof cladding on the roof.

The under flashing sheets 69, 71 and the starter sheets 1 1 are also important waterproofing elements of the invention.

As mentioned above, the applicant has realised that waterproofing is a significant technical issue for horizontally extending roof cladding sheets at the ends of the sheets at hips, valleys, and barge board sections of roofs, particularly in situations where rain sheets across roofs.

The under flashing sheet 69 shown in Figures 7 and 8 is formed to be used as an under flashing element for a section of a hip of the roof of Figures 1 to 4 or as an under flashing element for a section of a valley of the roof of Figures 1 to 4.

Figures 7 and 8 illustrate the under flashing sheet 69 in an orientation for use as an under flashing element for a section of a hip of the roof. This use of the flashing element 69 is further illustrated in Figure 13. The flashing sheet 69 is a structural element that contributes to the "structural" roof cladding of the roof. In this regard, the flashing element 69 is fastened directly to the roof frame, and the ends of the roof cladding sheets 9 are positioned on and secured directly to the flashing element 69 - see Figure 13.

The under flashing element 69 is an elongate element that is roll-formed or press-formed from steel strip and is curved in transverse section and includes parallel sides 75 and parallel ends 77. The flashing element 69 may be any suitable length and any suitable width. The flashing element 69 includes a central convex top wall section 85 and a plurality of parallel ribs 81 and troughs 83 extending along the length of the element 69. There are two troughs 83 on each side of the central top wall 85. There may be any suitable number of troughs 83. The combination of the ribs 81, troughs 83 and curved transverse section contribute to making the flashing element 69 a structural element to take the structural loads associated with walking on the flashing element 69 as well as the nearby roof sheets 9.

The troughs 83 of the flashing element 69 define channels for water flow. The arrangement is such that, when positioned as part of the roof, water that flows horizontally along the roof cladding sheets 9 will flow into the troughs 83 and then downwardly to the gutter 7. Having multiple troughs 83 provides a higher level of assurance that all water flowing onto the flashing element 69 will be captured and directed downwardly in the troughs 83 to the gutter 7.

It can be appreciated that when the flashing element 69 is used as an under flashing element for a section of a valley of the roof, the flashing element 69 will be used in the reverse orientation to that shown in Figures 7 and 8 as a concave element. In this orientation, the ribs 81 shown in Figures 7 and 8 define troughs and the troughs 83 shown in Figures 7 and 8 define ribs.

The under flashing sheet 71 shown in Figures 9 and 10 is formed to be used as an as under flashing element for the barge board section of the roof.

The under flashing sheet 71 is a structural element that contributes to the "structural" roof cladding of the roof. In this regard, the under flashing element 71 is fastened directly to the roof frame, and the ends of the roof cladding sheets 9 are positioned on and secured directly to the flashing element 71 - in a similar way to that shown in Figure 13 for the under flashing element 69. The under flashing sheet 71 is an elongate element that is roll-formed or press- formed from steel strip and includes parallel sides 87 and parallel ends 89. The under flashing element 71 may be any suitable length and any suitable width. The flashing element 71 includes two parallel ribs 91 and two troughs 93 extending along the length of the element 71. There may be any suitable number of troughs 93. The flashing element 71 also includes a downturned lip 95 that, in use is positioned against the barge board of the gable end of the roof. The combination of the ribs 91, the troughs 93 and the lip 95 contribute to making the flashing element 71 a structural element to take the structural loads associated with walking on the flashing element 71 as well as the nearby roof sheets 9.

The troughs 93 of the under flashing element 71 define channels for water flow. The arrangement is such that, when positioned as part of the roof, water that flows horizontally along the roof cladding sheets 9 will flow into the troughs 93 and then downwardly to the gutter 7. Having multiple troughs 93 provides a higher level of assurance that all water flowing onto the flashing element 71 will be captured and directed downwardly in the troughs 93 to the gutter 7.

With reference to Figure 14, another, although not the only other possible embodiment, of the roof starter sheet 1 1 between the gutter 7 of the roof and the first line of roof cladding sheets 9 adjacent the gutter 7 includes a reinforcing rib 37 extending along one side of the sheet and a flat section 41. With this arrangement, the downturned lip 27 of each roof cladding sheet 9 in the first line of roof cladding sheets overlies the reinforcing rib 37 of the flashing sheet 1 1 and the flat section 41 of the flashing sheet 11 extends over the channel defined by the gutter 7. The reinforcing rib 37 of the flashing sheet 1 1 forms a convenient attachment location for the roof cladding sheets 9 in the first line of roof cladding sheets. The reinforcing rib 37 also prevents any water that is blown under the first line of roof cladding sheets from entering the roof cavity.

Typically, with reference generally to the Figures, particularly Figures 2 to 4, the following steps are followed to install roof cladding sheets 9 on a roof frame.

• The roof starter sheets 11 are positioned on the roof frame so that the slightly inclined lip 99 extends over the channel defined by the gutter 7. The starter sheets 11 are secured directly to the roof frame via suitable fasteners (not shown).

The flashing sheets 69, 71 are positioned as required on the hips, valleys and barge boards of the roof frame and are secured directly to the roof frame via suitable fasteners (not shown) to the hip rafters 63 and the valley rafter 65. A first line of roof cladding sheets 9 is positioned so that the downturned side formation 27 of each sheet overlies the upwardly and inwardly curved lip 101 of the roof starter sheets 1 1. The roof cladding sheets 9 in the first line partially cover the roof frame, with the sheets 9 contacting and being supported structurally directly by the trusses 17 of the roof frame. Fasteners 103 secure the sheets 9 directly to the trusses 17. The lengths of the sheets 9 is selected so that the ends of the sheets 9 extend at least partially across and thereby overlie the flashing sheets 69, 71. The overlap ensures that water flowing horizontally across the roof is discharged into the troughs 83, 93 of the flashing sheets 69, 71. The upturned side formations 25 of the roof cladding sheets 9 in this first line provide effective reference points for locating the next line of roof cladding sheets 9 on the roof frame.

A second line of roof cladding sheets 9 is positioned on the roof frame. The downturned side formation 27 of each roof cladding sheet 9 in the second line of sheets is positioned to overlie the upturned side formations 25 of the roof cladding sheets 9 in the first line of sheets and thereby provide continuous coverage at the overlap. Hence, the upturned side formations 25 of the roof cladding sheets 9 in the first line of sheets cooperate with the downturned side formations 27 of the roof cladding sheets 9 in the next line of sheets to locate the next line of sheets 9 on the roof frame.

Each successive line of roof cladding sheets 9 is installed in the same way up the roof frame to the ridge rafter 61 of the roof.

When roof cladding sheets 9 are installed on both sides of the ridge rafters 61 shown in Figure 1, ridge caps (not shown) are positioned on the ridge rafters 61 to complete the installation of these sections of the roof.

When roof cladding sheets 9 are installed on both sides of the hip roof sections shown in Figure 1 , the over flashing sheets 67 are positioned on the flashing sheets 69 on the roof hips to complete the installation of these sections of the roof.

• When roof cladding sheets 9 are installed on both sides of the valley section shown in Figure 1, optional over-flashing sheets (not shown) are positioned on the flashing sheets 69 on the roof valley to complete the installation of this section of the roof.

It can readily be appreciated form the above sequence of installation steps that the structures and positions of the roof cladding sheets 9, starter sheets 1 1, flashing sheets 69, 71, and over flashing sheets 67 provides a high level of assurance that the roof is water proof and is a structural cladding as described above. The latter point is important from the perspective of the ongoing functionality of the roof and is also important in terms of safety for roof installers during the process of installing the roof.

Many modifications may be made to the embodiments of the invention described herein without departing from the spirit and scope of the invention.

By way of example, whilst the embodiments of the invention described in relation to the Figures include one particular profile for the roof cladding sheets 9, it can readily be appreciated that the invention is not limited to these particular profiles and extends to any suitable profiles.

In addition, by way of example, whilst the embodiments of the invention described in relation to the Figures include one particular roof configuration, it can readily be appreciated that the invention is not limited to this configuration and extends to any roof configuration.

In addition, by way of example, whilst the embodiments of the invention described in relation to the Figures include a roof frame having a plurality of parallel upright A-frame assemblies, it can readily be appreciated that the invention is not limited to this arrangement and extends to any arrangements.

In addition, by way of example, whilst the embodiments of the invention described in relation to the Figures include roof cladding sheets 9 that are made from a structural sheet as defined in Australian Standard AS 1562 Part 1 or 2, it can readily be appreciated that the invention is not limited to this sheet material. The cladding sheets 9 may be made from any suitable material in terms of material selection and structural capability. In addition, by way of example, whilst the embodiments of the invention described in relation to the Figures include a flashing sheet 69 that is formed to be used as an under flashing element for a section of a hip of a roof or as an under flashing element for a section of a valley of the roof, it can readily be appreciated that the invention is not limited to interchangeable elements and extend to different profiles for the hip and valley applications.

In addition, by way of example, the embodiments of the invention described in relation to the Figures may include solar roof panels and to arrangements that provide alternative functionality (acoustics, thermal storage, fire solutions) with or without solar functionality.

In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the end lap system and components of the end lap system as disclosed herein.