Roof truss assembly, system, method, and kit of parts

Abstract

A roof truss assembly comprises first and second mono-pitched roof trusses 104, 106 with base members 108, side members 110 and inclined rafters 112 that extend beyond the side members to create overh

Description

The present invention relates to a roof truss assembly, roof system, method of installing a roof system, a kit of parts for a roof system, and a roof truss. BACKGROUND Buildings can have flat roofs or pitched roofs. The invention relates to those buildings having a pitched roof. Pitched roofs are traditionally created using a number of roof trusses comprising wooden frames which are set upon the brick or timber-framed walls of a building, usually on a wall plate. A layer of waterproofing material is laid over the trusses, and battens are mounted thereupon which in turn supports tiles or an alternative outer roof covering. Conventional trusses that provide structural support to sloped roofs in buildings are well known. Trusses are of a substantially triangular shape and when in use comprise a horizontal member which defines the ceiling of the uppermost story of a building and two angled members (rafters) which define the pitched sides of the roof. UK Patent Application Publication No. 2051908 A discloses a prefabricated roof truss with a lower tie-beam fixed between principal rafters. Uprights extend between the tie-beam and the rafters and delimit the habitable area of the roof. A joist is spaced apart from the tie-beam and fixed to the uprights. The joist is rigidly connected to the tie-beam to form a beam which is capable of supporting a floor. UK Patent Application Publication No. GB2569224A discloses a mono-pitched roof module which comprises a number of mono-pitched roof trusses held in a spaced apart configuration by a structural support part. The module may be combined with a second module to form a two pitched roof. The structural support part may be made from a metal C-shaped beam. UK Patent Application Publication No. GB 2584912A discloses a modular pitched roof with two spaced apart outer pitched modules and a ridge module positioned between them. The ridge module extends between the two spaced apart outer pitched modules and defines the ridge of the roof. The two outer pitched modules define the pitch of the roof extending downwards from either side of the ridge module. A habitable space is located below the ridge portion. It is an object of the present disclosure to provide an improved roof truss construction. SUMMARY There is provided a roof truss assembly, roof system, method, kit of parts and roof truss as set out in the accompanying independent claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. According to a first aspect of the present disclosure, there is provided a roof truss assembly. The roof truss assembly comprises a first mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter. The inclined rafter extends beyond the side member to create a rafter overhang region. The roof truss assembly comprises a second mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter. The inclined rafter extends beyond the side member to create a rafter overhang region. The rafter overhang region of the first mono-pitched roof truss meets the rafter overhang region of the second mono-pitched roof truss at an apex of the roof truss assembly such that the side member of the first mono-pitched roof truss is spaced apart from the side member of the second mono-pitched roof truss, and a roof space is formed below the rafter overhang regions. Advantageously, the roof truss assembly comprises first and second mono-pitched roof trusses. The mono-pitched roof trusses each effectively span only half of the width of the building and are thus easier to transport than dual-pitch roof trusses that span the whole width of the building. Moreover, mono-pitched roof trusses are easier to lift and install onto the building. Advantageously, the rafter overhang regions of the first and second mono-pitched roof trusses extend beyond the side member to create a rafter overhang region. When the first and second mono-pitched roof trusses are positioned together, a roof space is formed below the rafter overhang regions. The roof space, and in particular the collective roof spaces defined by a plurality of roof truss assemblies provides a useable space in the roof that can be used for storage or, in preferred examples, for housing utility equipment for the building such as mechanical, electrical, and plumbing (MEP) components. For modern buildings, such as domestic homes, it has become increasingly desirable to increase the energy efficiency of buildings as well as to decarbonise these new buildings. One such example which exemplifies these desires is the Future Homes Standard which is set to come into effect in England in 2025, wherein homes built into compliance with the standards set are expected to lead to a reduction in total carbon dioxide emissions by 75-80% in comparison to homes built to previous building standards. To meet this reduction, changes in Part L of the Building Regulations have been recently implemented to lay out the groundwork towards achieving the targets set by the Future Homes Standard. Of note, the development and adoption of low-carbon technologies such as for heating and power generation technologies in buildings, for example solar photovoltaics and heat recovery units, were identified as a means towards achieving the goals of the Future Homes Standard. The new technologies enabling constructors to meet the goals of the Future Homes Standard for instance, may have complex architecture of mechanical, electrical, and plumbing (MEP) components which must be integrated into the home. These components are typically housed in a form of utility cupboard. The utility cupboard can be constructed with a simplified input / output architecture to serve all the MEP components therein and integrated within the MEP architecture of the building as one single, modular unit. However, these utility cupboards may also have significant physical footprint in the building thereby resulting in a reduction of useable storage space in the living spaces for occupiers of newly built homes, for example for clothing and other objects that are frequently accessed by the residential occupants of a building. Advantageously, the roof truss assembly of the present disclosure provides a useable roof space for housing MEP components. The roof space may house at least part of a utility cupboard. This uses what would otherwise be wasted space in the roof to house the MEP components enabling buildings to meet energy efficiency targets without loss of storage space elsewhere in the home. The roof space formed below the rafter overhang regions may be free from or substantially free from roof-supporting structures such as struts, king posts, and / or queen posts. The roof space is therefore unobstructed. The base members may extend substantially horizontally. The base members may be beams. The base member may, at least partially, define a ceiling of an uppermost story of a building on which the roof truss assembly is arranged. The base members may be considered as collectively forming the horizontal bottom chord of the roof truss assembly. The side members may extend from an end of their respective base members. The side members may be connected to their respective base members. The side members may be upright support columns. The rafters may extend upwardly from their respective base members at an (acute) angle. The rafters may extend upwardly to their respective side members and beyond the side members to form the rafter overhang regions. The rafters may be connected to their respective base members and / or side members. The rafter overhang regions of the first and second mono-pitched roof trusses may extend beyond their respective base members. The base members may therefore not extend into the roof space. The rafter overhang regions may have a length of at least 1 meter. The rafter overhang regions may have a length of at least 1.2 meters. The rafter overhang regions may have a length of at least 1.4 meters. The first and second mono-pitched roof trusses may be prefabricated in a factory environment. Advantageously, prefabrication of the mono-pitched roof trusses can reduce cost of labour due to a reduction in building time and a reduction in the number of possible mistakes and setbacks. Essentially, prefabricated mono-pitched roof trusses can be assembled in facilities better suited to their assembly than a construction site, resulting in improved efficiency. According to a second aspect of the disclosure, there is provided a roof system. The roof system comprises a plurality of roof truss assemblies according to the first aspect of the disclosure. The plurality of roof truss assemblies are arranged in a spaced apart configuration such that the roof spaces of the plurality of roof truss assemblies are aligned with one another. Advantageously, the roof spaces of the plurality of roof truss assemblies are aligned with one another. The collective roof spaces provide a useable space in the roof that can be used for storage or, in preferred examples, for housing utility equipment for the building such as mechanical, electrical, and plumbing (MEP) components. Each of the roof spaces may have substantially the same shape and dimensions. The roof system may form all or part of a roof of a building. The plurality of roof truss assemblies may be held in a spaced apart configuration by a first structural support member that joins the first mono-pitched roof trusses of each of the roof truss assemblies together and a second structural support member that joins the second mono-pitched roof trusses of each of the roof truss assemblies together. The first and second structural support members may extend transversely to the plurality of roof truss assemblies. The first structural support member may be mechanically coupled to at least one of the side members of the first mono-pitched roof trusses. The second structural support member may be mechanically coupled to at least one of the side members of the second monopitched roof trusses. One or more of the mechanical couplings may use a mechanical coupling joint. The roof spaces may be formed below the rafter overhang regions and between the first and second structural support members. The first and second structural support members may be spaced apart from one another by a distance of at least 1.5 meters. In other words, the roof spaces may have a width of at least 1.5 meters. The first and second structural support members may be spaced apart from one another by a distance of at least 2 meters. The roof system may further comprise a floor assembly located in a region between the side members of the first mono-pitched roof trusses and the second mono-pitched roof trusses. The roof spaces may be formed below the rafter overhang regions and, at least partially, above the floor assembly. The floor assembly may be located between the first and second structural support members. The floor assembly may be attached to the first and second structural support members. The roof truss assemblies may be held spaced apart at a distance in a range of 12 inches to 48 inches. According to a third aspect of the disclosure, there is provided a method of installing a roof truss assembly according to the first aspect of the disclosure. The method comprises arranging the first and second mono-pitched roof trusses on the building such that rafter overhang regions of the first and second mono-pitched roof trusses meet at an apex of the roof truss assembly and the side members of the first and second mono-pitched roof trusses are spaced apart from one another. According to a fourth aspect of the disclosure, there is provided a method of installing a system according to the second aspect of the disclosure. The method comprises arranging the plurality of roof truss assemblies on walls of a building, for each roof truss assembly, the arranging comprises arranging the first and second mono-pitched roof trusses on the building such that rafter overhang regions of the first and second mono-pitched roof trusses meet at an apex of the roof truss assembly and the side members of the first and second mono-pitched roof trusses are spaced apart from one another. The plurality of roof truss assemblies are arranged in a spaced apart configuration such that the roof spaces of the plurality of roof truss assemblies are aligned with one another. The method may comprise arranging first and second structural support members on the building to hold the plurality of roof truss assemblies in a spaced apart configuration. The first structural support member joins the first mono-pitched roof trusses of each of the roof truss assemblies together. The second structural support member joins the second mono-pitched roof trusses of each of the roof truss assemblies together. The method may comprise arranging a floor assembly in a region between the side members of the first mono-pitched roof trusses and the second mono-pitched roof trusses. According to a fifth aspect of the disclosure, there is provided a kit of parts. The kit of parts comprises a first mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter, wherein the inclined rafter extends beyond the side member to create a rafter overhang region. The kit of parts comprises a second mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter, wherein the inclined rafter extends beyond the side member to create a rafter overhang region. The firstand second mono-pitched roof trusses are useable to form a roof truss assembly such as a roof truss assembly of the first aspect of the disclosure. The kit of parts may comprise a plurality of the first and second mono-pitched roof trusses. The plurality of first and second mono-pitched roof trusses are useable to form a plurality of roof truss assemblies such as for a roof system of the second aspect of the disclosure. The kit of parts may comprise a first structural support member arranged to join each of the first mono-pitched roof trusses together in a spaced apart configuration. The kit of part may comprise a second structural support member arranged to join each of the second mono-pitched roof trusses together in a spaced apart configuration. The kit of parts may comprise a floor assembly. According to a sixth aspect of the disclosure, there is provided a roof truss. The roof truss comprises a bottom chord. The roof truss comprises a pair of inclined rafters extending away from the bottom chord such that the rafters meet one another at an apex of the roof truss. The roof truss comprises a pair of apex webs that extend from the apex to the bottom chord. The apex webs extend at an angle such that a central triangular region is formed with sides defined by the bottom chord and apex webs. The roof truss comprises a joist coupled to the bottom chord and extending between the apex webs such that a roof space is formed between the apex webs and joist. The roof truss may be in the form of a Fink roof truss which the additional inclusion of a joist coupled to the bottom chord and extending between the apex webs. A roof space is formed between the apex webs and joist. The roof space is a useable space in the roof that can be used for storage or, in preferred examples, housing utility infrastructure for the building (house) such as mechanical, electrical, and plumbing (MEP) components. The joist is capable of supporting a floor / supporting the elements stored in the roof space such as MEP components. Coupling joists to bottom chords of roof trusses has been implemented before in attic-style roof trusses as acknowledged in the background section of this application. Attic trusses are typically only useable on short roof spans due to lack of structural efficiency. Moreover, attic trusses typically require steeply inclined rafters to provide adequate headroom for the attic space. Advantageously, the roof truss of the present disclosure does not use an attic-style roof truss, but instead a roof truss of a Fink or similar style with apex webs that form a triangular mesh pattern resulting in greater structural efficiency and allowing for the roof truss to span larger roof widths than attic-style trusses. The roof truss utilises the existing space formed between the apex webs of the roof truss as the useable roof space (e.g., for storing MEP components) such that substantial redesign or modification of the roof truss is not required. Moreover, the roof truss provides the joist coupled the bottom chord and extending (horizontally) between the apex webs so as to structurally support items (e.g., MEP components) housed within the roof space. The roof truss of the present disclosure utilities an existing roof truss design that is suited for spanning wide building openings, but not typically used as a useful roof space. The roof truss of the present disclosure beneficially includes a joist coupled to the bottom chord in the central triangular region between apex webs. The inclusion of the joist provides structural rigidity enabling the housing of MEP components and in particular heavy MEP components such as water tanks in the roof space. The central triangular region is typically in the form of an isosceles triangle. In other words, the apex webs are of equal length. The intersections of the apex webs with the bottom chord are equally spaced from a central line running from the apex to the bottom chord. The roof truss may further comprise a web that extends from the intersection of a first of the apex webs and the bottom chord to a first of the rafters. The roof truss may further comprise a web that extends from the intersection of a second of the apex webs and the bottom chord to a second of the rafters. The joist may be rigidly coupled to the bottom chord by a plurality of support posts. The ends of the joist may be attached to the apex webs. The roof truss may have a length of at least six meters. The roof truss may have a length of at least seven meters. The roof truss may have a length of at least 8 meters. According to a seventh aspect of the disclosure, there is provided a roofing system comprising a plurality of roof trusses of the sixth aspect of the disclosure. The plurality of roof trusses may be arranged such the roof spaces of the roof trusses are aligned with one another. BRIEF DESCRIPTION OF THE DRAWINGS Examples of the present disclosure will now be described with reference to the accompanying drawings, in which: Figure 1 shows a view of an example roof system installed on a building according to aspects of the present disclosure. Figure 2 shows a view from above of the roof system of Figure 1. Figure 3 shows a side-on view an example roof system installed on a building according to aspects of the present disclosure. Figure 4 shows a diagram of a mono-pitched roof truss useable in a roof system of Figures 1 to 3. Figure 5 shows a frame of a floor assembly useable in a roof system of Figures 1 to 3. Figure 6 shows a diagram of a supporting structure useable in a roof system of Figures 1 to 3. Figure 7 shows another example roof system installed on a building according to aspects of the present disclosure. Figure 8 shows a view from above of the roof system of Figure 7. Figure 9 shows a roof truss useable in the roof system of Figure 7. DETAILED DESCRIPTION The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents. It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Figures 1 to 6 show a roofing system 100 (Figures 1 to 3) and component parts of the roofing system 100 (Figures 4 to 6) according to aspects of the present disclosure. The roofing system 100 forms all or part of a roof of a building 10. The roofing system 100 comprises a plurality of roof truss assemblies 102. Ten roof truss assemblies 102 are shown in this example but more or fewer roof truss assemblies may be provided depending on the desired roof for the building. Each roof truss assembly 102 spans across the width of the building 10 between walls 12 and 14. The plurality of roof truss assemblies 102 are spaced apart from one another along the direction of walls 12 and 14 (referred to as the transverse direction). The spacing of the roof truss assemblies 102 is typically in the range of between 12 inches to 48 inches. Different spacings of roof truss assemblies 102 may be used depending on the desired roof for the building. Each roof truss assembly 102 comprises a first mono-pitched roof truss 104 and a second monopitched truss 106. The first and second mono-pitched roof trusses 104, 106 each comprise a base member 108, a side member 110, and a rafter 112. The base member 108 is a beam that extends substantially horizontally. The side member 110 is an upright support column that extends upwardly from the base member 108 and, in particular, extends from an end of the base member 108. The side member 110 is connected to the base member 108 such as by a gusset plate. The side member 110 extends perpendicularly to the base member 108 to form a right-angle. The side member 110 is joined to an end of the base member 108 to form a right-angled corner in this example. The rafter 112 is an inclined rafter. The rafter 112 extends upwardly from the base member 108 at an acute angle. The angle is 30 degrees in this example. The rafter 112 is connected to the base member 108 such as by a gusset plate. The rafter 112 extends upwardly to the side member 110. The rafter 112 is connected to the side member 110 such as by a gusset plate. The rafter 112 extends beyond the side member 110 and base member 108 to form a rafter overhang region 114. The rafter 112 also extends, at the opposite end to the rafter overhang region 114, downwardly from the base member 108 to form an eave portion 116. A diagonal support beam 118 extends from the intersection of the side member 110 and base member 108 up to the rafter 112. The diagonal support beam 118 is connected to the side member 110 I base member 108 / rafter 112 such as by gusset plates. In addition, a post 120 extends upwardly from the base member 108 to the intersection of the diagonal support beam 118 and rafter 112. The post 120 is connected to the base member 108 / rafter 112 such as by gusset plates. In this example, the base member 108 has a length of 3064 mm. The distance from the bottom of the base member 108 to the top of the side member 110 is 1769 mm. The rafter overhang region 114 extends, in the vertical direction, by 945 mm and in the horizontal direction by 1342 mm. The rafter overhang region 114 has a length therefore of approximately 1641 mm. The eave portion 116 extends in the horizontal direction by 450 mm. Other dimensions are possible for the roof truss assemblies 102. The first and second mono-pitched roof trusses 104, 106 are typically prefabricated in a factory environment. This helps ensure greater consistency in roof truss construction and reduces the build time on site. The first mono-pitched roof truss 104 and second mono-pitched roof truss 106 are arranged together in a mutually opposing manner. The rafter overhang region 114 of the first mono-pitched roof truss 104 meets the rafter overhang region 114 of the second mono-pitched roof truss 104 at an apex 122 of the roof truss assembly 102. The rafter overhang regions 114 abut together at their ends. The rafter overhang regions 114 may be joined together such as by a gusset plate. The first mono-pitched roof truss 104 and second mono-pitched roof truss 106 collectively form a dual-pitched roof truss. Due to the rafter overhang regions 114, the side members 110 of the first mono-pitched roof truss 104 and second mono-pitched roof truss 106 are spaced apart from one another. In this way, a roof space 124 is formed below the rafter overhang regions 114. The roof space 124 is devoid of or substantially devoid of supporting structures such as beams, struts, king posts, and / or queen posts. The side members 110 and base members 108 do not obstruct or interfere with the roof space 124. Beneficially, the roof truss assembly 102 is composed of separate mono-pitched trusses 104,106 which can be more easily transported to site and simply installed together on the building. The design of the mono-pitched trusses 104, 106 means that an unobstructed roof space 124 is inherently formed in the roof truss assembly 102. The roof spaces 124 of the plurality of roof truss assemblies 102 are aligned to collectively define a useable space within the roof which may not otherwise have been provided. The roof spaces 124 can be used, for example, to house utility infrastructure (e.g., mechanical, electrical, and / or plumbing components) and may form a utility cupboard for the building. Only part of the roof spaces 124 may be used to form a cupboard. The roof space 124 may be multipurpose. The plurality of roof truss assemblies 102 are held in the spaced apart configuration by first structural support member 126 and second structural support member 128. The first structural support member 126 joins the first mono-pitched roof trusses 104 of each of the roof truss assemblies 102 together. The first structural support member 126 extends transversely to the plurality of roof truss assemblies 102. The first structural support member 126 extends across the full depth of the building between walls 16 and 18. The first structural support member 126 is mechanically coupled to at least one, and typically all, of the side members 110 of the first mono-pitched roof trusses 104. The first structural support member 126 is mechanically coupled such as by a mechanical coupling joint. The second structural support member 128 joins the second mono-pitched roof trusses 106 of each of the roof truss assemblies 102 together. The second structural support member 128 extends transversely to the plurality of roof truss assemblies 102. The second structural support member 128 extends across the full depth of the building between walls 16 and 18. The second structural support member 128 is mechanically coupled to at least one, and typically all, of the side members 110 of the second mono-pitched roof trusses 106. The second structural support member 128 is mechanically coupled such as by a mechanical coupling joint. The roof spaces 124 are formed below the rafter overhang regions 114 and between the first and second structural support members 126, 128. In the example shown in the drawings, the first and second structural support members 126, 128 are spaced apart by a distance of 2.4 meters. This defines the maximum width of the roof spaces 124. The first and second structural support members 126, 128 in this example both comprise two spaced apart beams 134, 136 (Figure 6) held at their ends by two end posts 138, 140 as well as two further intermediate posts 142, 144 equi-spaced apart from the end posts 138, 14O.Three reinforcing webs 146, 148, 150 extend diagonally between the rectangular frames formed by two adjacent posts and the beams 134, 136. The first and second structural support members 126, 128 may extend along part of the height of the side members 110 or along the full height of the side members 110. In this example, the first and second structural support members 126, 128 each have a length of 5769 mm and a height of 1000 mm. In this example, the first and second structural support members 126, 128 have a laminated construction and in particular have a three ply construction. Significantly, the first and second structural support members 126, 128 can have a variety of different constructions and could, for example, comprise glue laminated beams, steel beams, structural insulated panels, or timber beams. The roof system 100 further comprises a floor assembly 130. The floor assembly 130 is located in a region between the side members 110 of the first and second mono-pitched roof trusses 104, 106, and in particular are located between the first and second structural support members 126, 128. The floor assembly 130 is mechanically coupled to the first and second structural support members 126, 128. The floor assembly 130 comprises at least one and, in this example, a plurality of frames 132 that extend between the first and second structural support members 126, 128. In this example, five frames 132 are provided. Each of the five frames 126, 128 are positioned such that they are substantially aligned with one of the truss assemblies 102. The frames 132 in this example each comprise two spaced apart beams 152, 154 (Figure 5) held at their ends by two end posts 156, 158 as well an intermediate post 160 equi-spaced apart from the end posts 156,158. Two reinforcing webs 162,164 extend diagonally between the rectangular frames formed by two adjacent posts and beams 152, 154. The frames 132 in this example have a length of 2400 mm and a height of 500 mm. The floor assembly 130 therefore forms an elevated floor which is raised above the bottom of the roof structure as defined by the base members 108. The floor is not required to be elevated in all examples. In this example, the floor assembly 130 only comprises five frames such that the floor assembly 130 only extends across part of the roof. The remainder of the roof is not required to have a floor assembly or may have a different floor assembly such as to define a floor of a different height. The floor assembly 130 in this example is designed to support a WOOL water tank. The weight of the 1000L water tank is spread over five of the roof truss assemblies 102 that are associated with the floor assembly 130. Typically water tanks vary from 250 L and 1000 L and thus the roof system 100 of the present is able to support water tanks as typically used in dwellings. The roof spaces 124 are formed below the rafter overhang regions 114 and above the floor assembly 130 (where included). The roof system 100 is typically delivered to the building site as a kit of parts which comprise a plurality of first mono-pitched roof trusses 104, a plurality of second mono-pitched roof trusses 106, a first structural support member 126, and a second structural support member 128. The kit of parts may also comprise the floor assembly 130. The method of installing the roof system 100 on the building comprises arranging the plurality of roof truss assemblies 102 on the walls 12, 14 of the building 10. For each roof truss assembly 102, the arranging comprises arranging the first and second mono-pitched roof trusses 104, 106 on the building 10 such that rafter overhang regions 114 of the first and second mono-pitched roof trusses 104, 106 meet at an apex 122 of the roof truss assembly 102 and the side members 110 of the first and second mono-pitched roof trusses 104, 106 are spaced apart from one another. The plurality of roof truss assemblies 102 are arranged in a spaced apart configuration such that the roof spaces 124 of the plurality of roof truss assemblies 102 are aligned with one another The method further comprises arranging first and second structural support members 126, 128 on the building 10 to hold the plurality of roof truss assemblies 102 in the spaced apart configuration. The first structural support member 126 joins the first mono-pitched roof trusses 104 of each of the roof truss assemblies 102 together and the second structural support member 128 joins the second mono-pitched roof trusses 106 of each of the roof truss assemblies 102 together. The mono-pitched roof trusses 104, 106 and structural support members 126, 128 can be lifted and positioned using a crane or other lifting mechanism. Typically, the method further comprises arranging the floor assembly 130 in a region between the side members 110 of the first mono-pitched roof trusses 104 and the second mono-pitched roof trusses 106. Figures 7 to 9 show another example roofing system 200 according to aspects of the present disclosure. The roofing system 200 comprises a plurality of dual-pitched roof trusses 202. Ten roof trusses 202 are shown in this example but more or fewer roof truss assemblies may be provided depending on the desired roof for the building. Each roof truss 202 spans across the width of the building 10 between walls 12 and 14. The plurality of roof trusses 202 are spaced apart from one another along the direction of walls 12 and 14. The spacing of the roof trusses 202 is typically in the range of between 12 inches to 48 inches. Different spacings of roof trusses 202 may be used depending on the desired roof for the building. Each of the roof trusses 202 in this example are in the form of a Fink truss (also known as a W truss). The roof trusses 202 comprise a horizontal bottom chord 204, and inclined rafters 206, 208 which meet at the apex 210 of the truss 202. The inclined rafters 206, 208 extend upwardly from the bottom chord 204 at an acute angle. The angle is 35 degrees in this example. The inclined rafters 206, 208 extend upwardly from opposing ends of the horizontal bottom chord 204. The inclined rafters 206, 207 are connected to the bottom chord 204 such as by a gusset plate. The inclined rafters 206, 208 are connected together at the apex 210 such as by a gusset plate. A pair of apex webs 212, 214 extend from the apex 210 to the horizontal bottom chord 204. The apex webs 212, 214 extend away at an angle such that a central triangular region is formed with sides defined by bottom chord 204 and apex webs 212, 214. The apex webs 212, 214 are connected to the rafters 206, 208 and bottom chord 204 such as by gusset plates. The central triangular region is in the form of an isosceles triangle. The apex webs 212, 214 are of equal length and equally spaced from a central line running from the apex 210 to the horizontal bottom chord 204. A web 216 extends from the intersection of the apex web 212 and the bottom chord 204 to the rafter 206. A web 218 extends from the intersection of the apex web 214 and the bottom chord 204 to the rafter 208. The webs 216, 218 are connected to the rafters 206, 208 and bottom chord 204 such as by gusset plates. Unlike conventional Fink trusses, a joist 220 is provided. The joist 220 is mounted so as to be connected to, but spaced apart from the bottom chord 204. The joist 220 does not extend over the full length of the bottom chord 204, but instead only extends over part of the length of the bottom chord 204 between the apex webs 212, 214. The joist 220 is thus located in the central triangular region defined by bottom chord 204 and apex webs 212, 214. A roof space 222 is formed between the apex webs 212, 214 and the joist 220. The roof spaces 222 of the plurality of roof trusses 202 are aligned to collectively define a useable space for the roof which may not otherwise have been provided. The roof spaces 222 can be used, for example, to house utility infrastructure such as mechanical, electrical, and / or plumbing components and may form a utility cupboard for the building. Only part of the roof space 124 may be used to form a cupboard. The roof space 222 may be multipurpose. In this example, the roof spaces 222 can support a 1000 litre water tank spread over five of the trusses 202. The joist 220 is rigidly coupled to the bottom chord beam 204 by a plurality (three in this example) of support posts 224. The ends of the joist 220 may also be attached to the apex webs 212, 214. In this example, the roof trusses 202 have a length of 9710 mm and a height (from bottom chord 204 to apex 210) of 3203 mm. The bottom chord 204 has a length of 8810 mm. Other forms of roof truss may be used, provided they have apex webs 212,214 and form a central triangular region. The roof trusses 202 are typically pre-fabricated and transported to the building site. In use, the plurality of roof trusses 202 are lifted on to the building. In summary, there is provided a roof truss assembly 102 that comprises first and second monopitched roof trusses 104, 106 with inclined rafters 112 that extend to create rafter overhang regions 114. The overhang regions 114 meet at an apex 122 of the assembly 102 such that an unobstructed roof space is formed below the overhang regions 114. There is provided a roof system 100 which comprises a plurality of the assemblies 102. The assemblies 102 may be held in the spaced apart configuration by first and second structural support members 126, 128. A floor assembly 130 may be provided such that the roof space 124 is defined between overhang regions 114 and floor assembly 130. The roof space 124 may be used to house utility infrastructure for a building. Another roof truss design is provided in which a joist is coupled to a bottom chord of the roof truss and extends between apex webs of the roof truss. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A roof truss assembly comprising:a first mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter, wherein the inclined rafter extends beyond the side member to create a rafter overhang region; anda second mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter, wherein the inclined rafter extends beyond the side member to create a rafter overhang region,wherein the rafter overhang region of the first mono-pitched roof truss meets the rafter overhang region of the second mono-pitched roof truss at an apex of the roof truss assembly such that the side member of the first mono-pitched roof truss is spaced apart from the side member of the second mono-pitched roof truss, and a roof space is formed below the rafter overhang regions.

2. A roof truss assembly as claimed in claim 1, where the roof space is substantially free from roof-supporting structures such as struts, king posts, and / or queen posts.

3. A roof truss assembly as claimed in any preceding claim, wherein the rafter overhang regions of the first and second mono-pitched roof trusses extend beyond their respective base members.

4. A roof truss assembly as claimed in any preceding claim, wherein the rafter overhang regions have a length of at least 1 meter.

5. A roof truss assembly as claimed in claim 4, wherein the rafter overhang regions have a length of at least 1.2 meters.

6. A roof truss assembly as claimed in claim 5, wherein the rafter overhang regions have a length of at least 1.4 meters.

7. A roof truss assembly as claimed in any preceding claim, wherein the first and second mono-pitched roof trusses are prefabricated in a factory environment.

8. A roof system comprising a plurality of roof truss assemblies as claimed in any preceding claim, wherein the plurality of roof truss assemblies are arranged in a spaced apart configuration such that the roof spaces of the plurality of roof truss assemblies are aligned with one another.

9. A roof system as claimed in claim 8, wherein the plurality of roof truss assemblies are held in the spaced apart configuration by a first structural support member that joins the first mono-pitched roof trusses of each of the roof truss assemblies together and a second structural support member that joins the second mono-pitched roof trusses of each of the roof truss assemblies together.

10. A roof system as claimed in claim 9, wherein the first and second structural support members extend transversely to the plurality of roof truss assemblies, wherein the first structural support member is mechanically coupled to at least one of the side members of the first mono-pitched roof trusses, and wherein the second structural support member is mechanically coupled to at least one of the side members of the second mono-pitched roof trusses.

11. A roof system as claimed in claim 9 or 10, wherein the roof spaces are formed below the rafter overhang regions and between the first and second structural support members.

12. A roof system as claimed in any of claims 9 to 11, wherein the first and second structural support members are spaced apart from one another by a distance of at least 1.5 meters.

13. A roof system as claimed in claim 12, wherein the first and second structural support members are spaced apart from one another by a distance of at least 2 meters.

14. A roof system as claimed in any of claims 8 to 13, further comprising a floor assembly located in a region between the side members of the first mono-pitched roof trusses and the second mono-pitched roof trusses, and wherein the roof spaces are formed below the rafter overhang regions and, at least partially, above the floor assembly.

15. A roof system as claimed in any of claims 8 to 14, wherein the roof truss assemblies are spaced apart at a distance in a range of 12 inches to 48 inches.

16. A method of installing a roof system as claimed in any of claims 8 to 15, the method comprising:arranging the plurality of roof truss assemblies on walls of a building, for each roof truss assembly, the arranging comprises arranging the first and second mono-pitched roof trusses on the building such that rafter overhang regions of the first and second monopitched roof trusses meet at an apex of the roof truss assembly and the side members of the first and second mono-pitched roof trusses are spaced apart from one another, andwherein the plurality of roof truss assemblies are arranged in a spaced apart configuration such that the roof spaces of the plurality of roof truss assemblies are aligned with one another.

17. A method as claimed in claim 16, further comprising arranging first and second structural support members on the building to hold the plurality of roof trusses assemblies in the spaced apart configuration, wherein the first structural support member joins the first mono-pitched roof trusses of each of the roof truss assemblies together and the second structural support member joins the second mono-pitched roof trusses of each of the roof truss assemblies together.

18. A method as claimed in claim 16 or 17, further comprising arranging a floor assembly in a region between the side members of the first mono-pitched roof trusses and the second mono-pitched roof trusses.

19. A kit of parts comprising:a first mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter, wherein the inclined rafter extends beyond the side member to create a rafter overhang region; anda second mono-pitched roof truss comprising: a base member; a side member extending upwardly from the base member; and an inclined rafter, wherein the inclined rafter extends beyond the side member to create a rafter overhang region,wherein the first and second mono-pitched roof trusses are useable to form a roof truss assembly.

20. A kit of parts as claimed in claim 19, comprising a plurality of the first mono-pitched roof trusses and a plurality of the second mono-pitched roof trusses.

21. A kit of parts as claimed in claim 20, further comprising a first structural support member arranged to join each of the first mono-pitched roof trusses together in a spaced apart configuration; and a second structural support member arranged to join each of the second mono-pitched roof trusses together in a spaced apart configuration,22. A roof truss comprising:a bottom chord;a pair of inclined rafters extending away from the bottom chord such that the rafters meet one another at an apex of the roof truss;a pair of apex webs that extend from the apex to the bottom chord, the apex webs extend at an angle such that a central triangular region is formed with sides defined by the bottom chord and apex webs; anda joist coupled to the bottom chord and extending between the apex webs such that a roof space is formed between the apex webs and joist.

23. A roof truss as claimed in claim 22, wherein the ends of the joist are attached to the apex webs.

24. A roof truss as claimed in any of claims 22 to 23, wherein the roof truss has a length of at least six meters, optionally wherein the roof truss has a length of at least seven meters, and optionally wherein the roof truss has a length of at least 8 meters.

25. A roof system comprising a plurality of roof trusses as claimed in any of claims 22 to 24, wherein the plurality of roof trusses are arranged such that the roof spaces of the roof trusses are aligned with one another.

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