Insulation unit

Abstract

An insulation unit for installation in a building construction comprising an adjacent pair of rafters 8, 10 supported on a wall 6, the insulation unit comprising a tray 40, insulation material 42 atta

Description

Field of the Invention The present invention relates to an insulation unit. In particular, but not exclusively, the invention relates to an insulation unit for a building construction featuring a junction between a roof structure and a supporting wall. Aspects of the invention relate to an insulation unit, to a kit of parts, to a building construction, and to a building. Background to the Invention In building constructions, a roof structure meets a supporting wall, such as an exterior wall, at a so-called eaves junction. More specifically, the eaves junction typically refers to the junction between an inclined rafter of the roof structure, a horizontal ceiling joist that connects the rafters at ceiling level, and a wall plate fixed atop the supporting wall to support the roof structure. The supporting wall is typically insulated and often takes the form of a cavity wall, having an interior leaf, an exterior leaf and a cavity defined between the leaves, which is filled with insulating material. The loft space, defined above the ceiling level, may also be insulated, for example with layers of glass wool being laid between the ceiling joists. However, at the eaves junction, there is often a lack of adequate insulation (particularly in older building constructions), which forms a discontinuity between the wall insulation and the loft insulation. The lack of suitable insulation means that the eaves junction is susceptible to cold bridging and the formation of cold spots on internal surfaces of the external walls, which increases the risk of condensation and mould growth inside the building. It is therefore desirable to insulate the eaves junction to mitigate such effects. However, retrofitting insulation in this area is a difficult task since access to the eaves junction is limited (in part, due to the presence of roof coverings supported on the rafters). It is therefore difficult to reliably fit insulation material through the gap that exists between the wall plate and the roof covering, and around the junction. This issue is further exacerbated by the wide variation of existing housing stock, particularly in the UK. As such, there is significant variation of the rafter dimensions and the spacing between rafters, while the rafters may also be supported on coplanar joists or by out-of-plane joists. The pitch of the roof structures also varies significantly between buildings and such variability makes it difficult to design an off-the-shelf retrofit insulation solution for the eaves junction. Additionally, if warm humid air from the living space of the building passes into the loft space moisture in the air can condense on cold surfaces. The moisture may condense on insulation, rafters, joists, and belongings, damaging such items, reducing their effectiveness and forming undesirable scents. In some cases, the condensed moisture can potentially lead to rafter rot, which can damage the structural integrity of the property. It is therefore important to ensure that there is suitable ventilation in the loft space to avoid stagnant air and condensation. However, whilst ventilation devices for installation at the eaves junction are known for this purpose, such devices are often improperly installed and become blocked, making such devices ineffective. It is therefore a significant challenge to retrofit insulation at the eaves junction, whilst ensuring that ventilation is maintained in this problematic and highly variable area. The present invention has been devised to mitigate or overcome at least some of the above-mentioned problems. Summary of the Invention According to an aspect of the present invention, there is provided an insulation unit for installation in a building construction. The building construction comprises an adjacent pair of rafters supported on a wall (for example, on a wall plate). The insulation unit comprises: a tray having: an upper surface and an opposing lower surface; a length extending along a longitudinal axis from a proximal first end to a distal second end, and a width extending along a transverse axis from a first side to an opposing second side. The insulation unit further comprises insulation material attached to the lower surface of the tray and extending along the longitudinal axis for insertion around an edge of the wall (or wall plate) so as to extend between first and second insulation spaces either side of the edge. The insulation unit further comprises one or more mounting elements extending away from the first and second sides of the tray, along the transverse axis, for engagement with first and second opposing surfaces of the adjacent pair of rafters. The one or more mounting elements are attachable to the first and second opposing surfaces of the rafters to support the tray in an inclined position, for example for forming a ventilation channel between the tray and a covering, such as a roof covering, supported on the rafters. In this manner, the insulation unit may be inserted between an adjacent pair of rafters, and through a gap between the edge of the wall and the roof covering. Once inserted, the insulating material extends around the edge of the wall to form a bridge around the junction, connecting the first and second insulation spaces (such as a wall and loft insulation space), and forming a continuous quilt for mitigating heat transfer between interior and exterior spaces. Advantageously, the mounting element(s) remain accessible once the insulation unit has been installed around the junction and the mounting element(s) are attachable to first and second opposing surfaces of the rafters to secure the insulation unit in the inclined position. In this manner, the mounting element(s) secure the ventilation tray against, or opposing, the roof covering so as to form ventilation channel(s) for the loft space, mitigating the risk of condensation and / or rafter rot. The insulation unit may therefore advantageously be installed during assembly of the building construction, e.g. prior to fitting the roof covering to the rafters, and / or the insulation unit may be retrofit to existing housing stock, i.e. where the roof covering is already in place. In an example, the insulation material may be attached to a proximal portion of the tray and the one or more mounting elements may extend from a distal portion of the tray. In this manner, the insulation material, at the proximal end of the tray may be inserted through a gap between the wall and the roof covering and the one or more mounting elements at the opposing distal portion of the tray remain accessible for subsequently securing the insulation unit in position. For example, the one or more mounting elements may extend from a position at the second end of the tray or a position that is offset from the second end of the tray by a distance less than or equal to a third of the length of the tray, optionally, a distance less than or equal to a quarter of the length of the tray. In an example, the one or more mounting elements may comprise a flexible mounting element. The flexible mounting element may, for example, be tensible for attachment to the first and / or second opposing surfaces of the rafters to support the tray in the inclined position. The flexible mounting may therefore be easily manoeuvrable and repositionable to engage the rafter(s) and conveniently secure the insulation unit in position. The flexible mounting element may, for example, take the form of a strap, cord, or rope, for attachment to the first and / or second opposing surfaces of the rafters. In an example, the one or more mounting elements may comprise a pair of flexible mounting elements. Each flexible mounting element may extend from a respective one of the first and second sides of the tray for attachment to a respective one of the first and second opposing surfaces of the rafters. In an example, the insulation material extends along the longitudinal axis from a first end portion to a distal second end portion. Optionally, the first end portion may project beyond the first end of the tray in a proximal direction. In this manner, the first end portion may be inserted further into the gap than the tray, e.g. for engagement with insulation in a cavity of the wall. For example, the first end of the tray may project beyond the first end portion of the insulation material in a proximal direction. Optionally, the first end of the tray may project beyond the first end portion of the insulation material by a length less than or equal to 1.9 m. This length is sufficient for engaging the wall insulation and forming a continuous quilt. The first end portion of the insulating material may, for example, be movable relative to the tray for insertion around the edge into the first insulation space while the second end portion of the insulating material extends into the second insulation space. In an example, the insulation material may extend along the transverse axis beyond the first and / or second sides of the tray. Optionally, the insulation material may comprise a compressible body of insulating material. The compressible body may be easily inserted into tight spaces and the resilience may help to retain the body in situ. Optionally, the body may be made of at least one of: a polyurethane board; aerogel; glass wool; polyester wool; mineral wool, such as a rock fibre mineral wool; sheep wool; or cork. The body may, for example, have a substantially uniform thickness, orthogonal to the longitudinal and transverse axes, of less than or equal to 0.4m. Optionally, the body may have a substantially uniform thickness, orthogonal to the longitudinal and transverse axes, greater than or equal to 5 mm. In an example, the insulation material may comprise a protective layer encapsulating the body. The protective layer may be a water-resistant or waterproof material. In an example, the insulating material may be attached to the tray by bonding, such as ultrasonic welding or heat welding; adhesive; and / or mechanical fixing. Optionally, the one or more mounting elements may be attached to the tray by bonding, such as ultrasonic welding or heat welding; adhesive; and / or mechanical fixing. Optionally, the tray may be a ventilation tray comprising a plurality of air guiding formations on the upper surface for guiding an airflow along the ventilation channel. In this manner, the tray may provide more effective ventilation of a loft space of the building construction. According to another aspect of the invention, there is provided a kit of parts comprising: a tray; insulation material; and one or more mounting elements; for forming an insulation unit as described in a previous aspect of the invention. According to yet another aspect of the invention, there is provided a building construction comprising: a pair of rafters supported on a wall; and an insulation unit as described in a previous aspect of the invention. The insulation material may, for example, extend around an edge of the wall between first and second insulation spaces either side of the edge; and the one or more mounting elements may be attached to opposing surfaces, defined by the pair of rafters, to support the tray in an inclined position. Optionally, the building construction may further comprise a covering supported on the rafters. The tray may be supported in the inclined position to form a ventilation channel between the tray and the covering. In an example, the insulation material may fill a space between the wall and the tray, supporting the tray in the inclined position. The tray may be supported substantially in alignment with a plane extending between the pair of rafters orthogonal to the first and second vertical surfaces, According to yet another aspect of the present invention, there is provided a building construction comprising: a pair of rafters supported on a wall; a pair of joists, each joist being connected to a respective one of the pair of rafters at an elevated height relative to the wall to define a raked ceiling; and an insulation unit, as described in a previous aspect of the invention, arranged between the pair of rafters for insulating the raked ceiling. The one or more mounting elements attach to opposing surfaces, defined by the pair of rafters, to support the tray in an inclined position. According to a still further aspect of the invention, there is provided a building comprising: an insulation unit as described in a previous aspect of the invention; or a building construction as described in another previous aspect of the invention. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. Brief Description of the Drawings In order that the invention may be more readily understood, preferred non-limiting embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic perspective view of an insulation unit, according to an embodiment of the present invention, arranged in situ in an exemplary building construction; Figure 2 is a front view of the insulation unit, shown in Figure 1, in situ; Figure 3 is a cross-sectional side view of the insulation unit, shown in Figure 1, in situ; Figure 4 is a schematic perspective view of an exemplary ventilation tray of the insulation unit shown in Figure 1; Figure 5 is an end view of the ventilation tray shown in Figure 4; Figure 6 is a side view of the ventilation tray shown in Figure 4; Figure 7 is a schematic perspective view of exemplary insulation material of the insulation unit shown in Figure 1; Figure 8 is an end view of the ventilation tray shown in Figure 7; Figure 9 is a side view of the ventilation tray shown in Figure 7; Figure 10 is a schematic plan view of an exemplary mounting element of the insulation unit shown in Figure 1; Figure 11 is a side view of the mounting element shown in Figure 10; Figure 12 is a schematic perspective view of the assembled insulation unit shown in Figure 1; Figure 13 is a schematic plan view of the insulation unit shown in Figure 12; Figure 14 is an end view of the insulation unit shown in Figure 12; Figure 15 is a side view of the insulation unit shown in Figure 12; Figure 16 schematically illustrates an exemplary method of installing the insultation unit, shown in Figure 1, in a building construction; and Figure 17 is a schematic perspective view of another exemplary building construction, in accordance with an embodiment of the present invention, to which the insulation unit of Figure 1 may be fitted. For the avoidance of any doubt, the directions up, down, left, right, forward, rearward, upward, and downward, are defined herein relative to the general orientation of the building constructions, as shown in the Figures. Detailed Description of Embodiments of the Invention In general terms, embodiments of the invention relate to an insulation unit for retrofitting to a building construction to insulate a junction, such as an eaves junction, between a roof structure and a supporting wall. Advantageously, the insulation unit provides suitable insulation around the junction, and between an adjacent pair of rafters whilst further defining a ventilation channel along the underside of a roof covering, supported on the rafters, for ventilating a loft space of the building construction. For this purpose, the insulation unit includes a ventilation tray, insulation material attached to a lower surface of the tray, and one or more mounting elements extending away from first and second opposing lateral sides of the tray. The mounting element(s) remain accessible once the insulation unit has been installed around the junction and the mounting element(s) are attachable to first and second opposing surfaces of the rafters to secure the insulation unit in position. In this manner, the inserted insulation material forms a bridge around the junction, connecting the loft insulation to the wall insulation, and the mounting element(s) secure the ventilation tray against, or opposing, the roof covering so as to form the ventilation channel(s) for the loft space. It is envisaged that embodiments of the invention will therefore lead to enhanced building insulation, reduced heating requirements, and improved loft space ventilation in building constructions. Embodiments of the invention shall now be discussed in more detail with reference to Figures 1 to 17. Figure 1 schematically shows a perspective view of an exemplary insulation unit 1, according to an embodiment of the present invention, installed in an exemplary building construction 2. As shown in Figure 1, the building construction 2 features a junction 3 between a roof structure 4 and a supporting wall 6, which may be an exterior wall of the building construction 2 for example. The roof structure 4 is supported by, and overhangs, the wall 6, forming an eave of the building construction 2. In this example, the junction 3 therefore forms an ‘eaves junction’ of the building construction 2. The roof structure 4 is shown to include a first rafter 8 and a laterally spaced apart second rafter 10. Together, the first and second rafters 8, 10 define an adjacent pair of rafters for supporting an overlying roof covering (not shown in Figure 1). Although a single pair of rafters 8, 10 is shown in this example, it shall be appreciated that the roof structure 4 will include a plurality of such rafters supporting the roof coverings and thereby defining a complete roof for the building construction 2. For context, the roof structure 4 may for example have a rafter spacing, i.e. a lateral spacing between adjacent rafters, that is greater than or equal to 150 mm, but generally less than or equal to 1200 mm. As shown in Figure 1, each rafter 8, 10 is inclined in a vertical direction to define a pitched roof. In examples, the roof pitch may be between approximately 10 degrees and 70 degrees, as commonly encountered in existing housing stock. A loft space 12 is defined in a space between the roof coverings and a panel 14, which defines a ceiling panel of a lower level of the building construction 2. In this example, the ceiling panel is substantially flat and planar. The roof structure 4 further includes a pair of ceiling joists 16 that extend horizontally in the loft space 12 to support the first and second rafters 8, 10. For example, as shown in Figure 1, the second rafter 10 is shown to be connected to, and supported by, an end of one of the celling joists 16. In this example, each rafter 8, 10 is arranged in planar alignment with the respective ceiling joist 16. That is, each rafter 8, 10 is arranged in the same vertical plane with the respective ceiling joist 16. However, this exemplary arrangement is not intended to be limiting on the scope of the invention, and it shall be appreciated that, in other examples, the rafters 8,10 may be supported by in-plane or out-of-plane joists, as both arrangements are commonly found in existing housing stock. It shall be appreciated that the loft space 12 above the ceiling panel 14 may be insulated, for example by laying or fitting insulating material (not shown in Figure 1) on top of the ceiling panel 14 either during construction of the roof structure 4 or thereafter as a retrospective fitting. Although not shown, the loft insulation may therefore extend along an upper surface of the ceiling panel 14 and extend between the adjacent pair of ceiling joists 16. The supporting wall 6 is shown to extend in a lateral direction, in this example, and defines an external wall of the building construction 2. The wall 6 is typically insulated and takes the form of a cavity wall in this example. As such, the wall 6 includes a first leaf 20 and an opposing second leaf 22, separated by an intermediate cavity 24 extending between the first and second leaves 20, 22. It shall be appreciated that the first leaf 20 forms an outer leaf of the wall 6 and the second leaf 22 defines an inner leaf of the wall 6 facing an interior living space. Although not shown in this example, the cavity 24 of the wall 6 is typically filled with an insulating material, defining a wall insulation. The cavity 24 may have been filled with insulating material during construction of the wall 6 and / or the insulating material may subsequently have been retrofitted to the cavity 24. For example, the wall 6 may have been built with full fill insulation, partial fill insulation, or the wall 6 may have been left uninsulated. Where the cavity 24 is only partially filled with insulation material, or left uninsulated, the cavity 24 may be retrofit with insulating materials, for example being filled with blown fibre insulation. The exemplary supporting wall 6 is not intended to be particularly limiting on the scope of the invention though, and it shall be appreciated that the wall 6 may take other suitable forms, in other examples, for example with insulation being installed internally or externally. Now considering the junction 3 between the roof structure 4 and the supporting wall 6 in more detail, it shall be appreciated that the eaves junction 3 is defined where the first and second rafters 8, 10 of the roof structure 4 meet, and overhang, the exterior wall 6 of the building construction 2. A wall plate 32 is affixed to, and extends along, an upper surface of the wall 6 for supporting the first and second rafters 8, 10, at the eaves junction 3. For example, the wall plate 32 may be bedded in with mortar and extend along the top of the inner leaf 22 of the wall 6, as shown in Figure 1. The ends of the ceiling joists 16 may rest atop the wall plate 32, supporting the first and second rafters 8, 10. In this manner, the wall plate 32 serves to spread the load of the supported roof rafters 8, 10. The wall plate 32 may, for example take the form of a bar of timber for this purpose, although this example is not intended to be particularly limiting on the scope of the invention. In conventional building constructions of this type, the eaves junction is frequently inadequately insulated and presents a discontinuation of the insulation in the space between the loft insulation and the wall insulation. As a result, the eaves junction is susceptible to cold bridging between the interior and exterior of the building construction. However, the insulation unit 1 is installed in the building construction 2 in order to insulate the eaves junction 3 in the space between the loft insulation and the wall insulation, and form one or more ventilation channels for ventilating the loft space 12. In particular, the insulation unit 1 may be retrofitted to a pre-existing building construction 2 of the type shown in Figure 1, or the insulation unit 1 may be installed during assembly of a new building construction, for example prior to securing the roof covering the rafters 8, 10. For this purpose, the insulation unit 1 is shown to include a ventilation tray (referred to as the ‘tray’ 40 in the following description), insulation material 42 attached to the tray 40, and one or more mounting element(s) 44 for attaching the installation unit 1 to the first and second rafters 8, 10. Such features shall now be described in more detail with additional reference to Figures 2 and 3. Figure 2 shows a front view of the insulation unit 1 arranged, in situ, between the first and second rafters 8, 10 of the building construction 2, and Figure 3 shows a cross-sectional view of the arrangement, along the line A-A (indicated in Figure 2), with a roof covering 46 shown to be supported on the rafters 8, 10. As best shown in Figure 3, the insulation material 42 is inserted into the restricted gap that exists between the wall plate 32 and the roof covering 46 in order to engage the wall insulation 47 and the loft insulation 48, either side of the eaves junction 3. In this manner, the insulating material 42 forms a continuous quilt around the eaves junction 3, thermally insulating the air inside a living space 50 of the building construction 2 (on an interior side of the wall 6) from the external airspace 52 outside of the building construction 2. For this purpose, the insulation material 42 may be inserted through the restricted gap and project through the gap by a distance, O, as shown in Figure 3, so as to engage the wall insulation 47. For example, the insulation material 42 may be inserted into the gap and project therethrough by a distance of up to 2000 mm in order to engage the wall insulation 47. In examples, the distance, O, may therefore be between 0 mm and 2000 mm, in order to engage the wall insulation 47 in different building constructions and thereby insulate the eaves junction 3. The tray 40 is configured to interact with the roof covering 46, in situ, to define one or more ventilation channel(s) 55 extending along a length of the tray 40, from a proximal first end 56 to a distal second end 58, as shown in Figure 3. The ventilation channel(s) 55 serve to ventilate the loft space 12. For example, as shown in Figure 3, the tray 40 is supported in an inclined position and interfaces with the roof covering 46 to define a pair of ventilation channels 55 that allow airflow between the external airspace 52 and the loft space 12. This provides a ventilating airflow that serves to mitigate the risk of mould growth in the loft space 12. As shown in Figure 3, the insulating material 42 is attached to a proximal portion of the tray 40 such that the insulating material 42 is insertable through the gap between the roof covering 46 and the wall plate 32 with the first end 56 of the tray 40. Once inserted, the insulating material 42 and the proximal portion of the tray 40 are partially supported by the wall plate 32. However, the mounting element(s) 44 extend from an opposing distal portion of the tray 40 and attach to the first and second rafters 8, 10 to secure the insulation unit 1 in the inclined position. In other words, the mounting element(s) 44 are attached to the first and second rafters 8, 10 to effectively hang the insulation unit 1 in position, with the free-hanging end of the insulation unit 1 being supported by the wall plate 32. As best shown in Figures 1 and 2, the mounting element(s) 44 extend from first and second opposing lateral sides 60, 62 of the tray 40 for this purpose, and the mounting element(s) 44 are securable to respective opposing inner surfaces 64, 66 of the first and second rafters 8,10 on respective lateral sides of the insulation unit 1. In this manner, the insulation unit 1 is suitably restrained in position and supported against the roof covering 46 so as to form the ventilating channels 55 that ventilate the loft space 12, whilst simultaneously insulating the junction 3 to mitigate heat transfer between the external airspace 52 and the living space 50. The exemplary insulation unit 1, and its constituent parts, shall now be considered in more detail with additional reference to Figures 4 to 15. Figures 4 to 6 show an exemplary embodiment of the tray 40, which is generally rectangular in this example. It shall be appreciated that the tray 40 may take other suitable shapes in other examples though. The tray 40 may be rigid or semi rigid, for example having sufficient rigidity to maintain its shape, in situ, whilst offering some flexibility for insertion around the eaves junction 3 and ease of installation. As best shown in Figures 4 and 6, the tray 40 has a length, F, extending along a longitudinal axis 70 from the proximal first end 56 to the distal second end 58. The tray 40 also has a width, E, extending from the first lateral side 60 to the opposing second lateral side 62, as best shown in Figure 5, and a depth, D, defined between a lower surface 72 and an opposing upper surface 74. The lower surface 72 of the tray 40 is configured for attachment to the insulation material 42 and the opposing upper surface 74 of the tray 40 is configured to interface with the roof covering 46, in situ. The tray 40 is shown to include first and second ventilation channels, 55a, 55b, in this example, which extend in parallel along the length, F, of the tray 40, as best shown in Figures 4 and 5. The tray 40 may therefore have a generally uniform shape along its length, F, but include a plurality of rib elements 76, or similar features, as shown in Figure 4, that may be arranged at regular or varied intervals along the length, F, for structural reinforcement. Although the tray 40 is shown to include first and second ventilation channels 55a, 55b in this example, it shall be appreciated that the tray 40 may include any number of ventilation channels, in other examples, and the ventilation channels themselves are not limited to any particular form. Indeed, ventilation trays with a range of upstanding features for channelling a ventilating airflow between the exterior space 52 and the loft space 12 are well known to the skilled person and are not described in detail here to avoid obscuring the invention. The first and second ventilation channels 55a, 55b generally take the form of a pair of U-shaped channel sections, in this example. Each ventilation channel 55a, 55b therefore includes a respective lower wall or web 76a, 76b and a pair of upstanding sidewalls or flanges 78a, 78b. The webs 76a, 76b of the ventilation channels 55a, 55b define the lower surface 72 of the tray 40, while the upstanding flanges 78a, 78b extend away from the lower surface 72 to define the opposing upper surface 74 of the tray 40. As shown in Figure 5, the ventilation channels 55a, 55b therefore defines an overall ventilation area, G, through which air flows, in use, along the channel 55a, 55b to ventilate the loft space 12. Again, it shall be appreciated that, although the ventilation channels 55a, 55b take the form of U-shaped channel section in this example, the number and configuration of the ventilation channels may take various suitable forms that are known in the art in other examples. The dimensions of the tray 40 may be standardised for respective building constructions. For context, the length, F, of the tray 40 may generally be greater than or equal to 100 mm, and generally less than or equal to 2500mm. The depth, D; width, E; and profile of the tray 40; are configured to ensure that the overall ventilation area, G, is large enough to conform to relevant building regulations. In particular, the ventilation area, G, is dictated by the ventilation regulations in the country where the product is installed, and the depth, D; width, E; and configuration of the ventilation channels; may be adapted to provide a conforming ventilation area, G, for that region. For context, the overall ventilation area, G, of the tray 40 may therefore be greater than or equal to 1,000 mm2 / m, but generally less than or equal to 250,000 mm2 / m in examples. Such dimensions are provided by way of example only though and are not intended to be limiting on the scope of the invention. The tray 40 is formed of a weather-resistant material in this example, such as Polyvinyl chloride (PVC). However, in other examples, it shall be appreciated that the tray 40 may be formed from a variety of suitable weather-resistant materials that are known in the art for forming such ventilation trays. The tray 40 may therefore be formed by a variety of suitable forming techniques, including vacuum forming, as shall be appreciated by the skilled person. Figures 7 to 9 show an exemplary embodiment of the insulation material 42. The insulation material 42 generally has a cuboidal shape in this example and includes a body portion 80, or core, which is encapsulated in a protective layer 82. The body portion 80 provides the rectangular shape in this example and has a certain degree of rigidity. For example, the body portion 80 may have sufficiently rigid to be stored and handled with ease, whilst also having some flexibility and resilience to facilitate installation into tight spaces, and self-retention thereafter. In this respect, it shall be appreciated that the cuboidal shape of the body portion 80 may offer various advantages in terms of its ease of handling and machining, as well as its ease of integration with surrounding insulation. However, this shape is not intended to be limiting on the scope of the invention and, in other examples, it shall be appreciated that the insulation material may take other suitable shapes and may take a loose form encapsulated in a protective layer. In such examples, the protective layer may, for example, bind the loose material together to define a shape, such as the cuboidal shape shown in Figures 7 to 9, or another suitable shape for filling the gap between the wall plate 32 and the underside of the roof covering 46. The body portion 80 has first and second opposing rectangular surfaces 84, 86, in this example, and a substantially uniform thickness, A, extending between the firstand second surfaces 84, 86, as best shown in Figure 8. The first and second surfaces 84, 86 of the body portion 80 are shown to be planar and substantially parallel in this example for arrangement in the gap between wall plate 32 and the roof covering 46. However, in other examples, it is anticipated that the first surface 84 may be inclined relative to the second surface 86, for example to define a wedge shape for urging the attached tray 40 into engagement with the roof covering 46. The body portion 80 is also shown to have a width, B, extending from a first lateral side 88 to an opposing second lateral side 90 of the body portion 80, and a length, C, extending from a first end 92 to an opposing second end 94 of the body portion 80, as best shown in Figure 9. In situ, the insulation material 42 extends laterally between the first and second rafters 8, 10 and longitudinally around the eaves junction 3 to bridge the gap between loft insulation 48 and the wall insultation. The width, B, of the insulation material 42 may therefore substantially correspond to the rafter spacing, i.e. the lateral spacing of the first and second rafters 8, 10. For example, the width, B, of the insulation material 42 may be substantially equal to the rafter spacing so that the first and second sides 88, 90 engage the opposing vertical surfaces 64, 66 of the first and second rafters 8, 10, in situ. In examples, the insulation material 42 may even be slightly wider than the rafter spacing and compressed between the first and second rafters 8, 10 to ensure an adequate seal. The body portion 80 of the insulating material 42 may therefore have some degree of compressibility, for example having 5 to 100 mm of lateral compressibility (corresponding to approximately 25% of the width, B). For context, typical rafter spacings may be approximately 600 mm in modern housing, but may be as large as 2000 mm and as short as 100 mm, for example at the end of a run of rafters. Accordingly, the width, B, of the insulation material 42 may take any such dimensions. The length, C, of the body portion 80 is generally determined by the respective distances for engaging the loft insulation 48 and the wall insulation 47, either side of the junction 3, and thereby forming a complete quilt around the junction 3. In part, the length, C, will therefore vary according to the depths of the loft insulation 48 and the wall insulation 47, i.e. the distance from the wall insulation 47 to the top edge of the wall plate 32 and the distance from that edge to the start of the loft insulation 48. In examples, the length, C, may therefore also vary between the building constructions according to the pitch angle of the roof structure 4, for example. Additionally, the length, C, may be constrained by the space available on the exterior side of the junction 3, for example as may be determined by a boxed soffit (not shown) enclosing the end of the rafters 8, 10 and connecting to an exterior surface of the wall 6. For context, the length, C, of the body portion 80 may be greater than or equal to 100mm but generally less than or equal to 2000 mm. However, these dimensions are exemplary only and are not intended to be limiting on the scope of the invention. The thickness, A, of the body portion 80 is configured to engage the wall plate 32, in situ, and urge the tray 40, attached to the first face 84 of the body portion 80, towards or into engagement with the roof covering 46. It shall be appreciated that the insulation unit 1 has an overall thickness, defined by the combined depth, D, of the tray 40 and thickness, A, of the body portion 80, and the overall thickness may therefore generally correspond to the span of the gap between the wall plate 32 and the roof covering 46 of the building construction 2. In this manner, the insulation unit 1 is able to suitably insulate the junction 3 and ventilate the loft space 12. In examples, the overall thickness may be undersized or oversized for the span of the gap. When the overall thickness, D, is oversized for the span of the gap, a compression fit may be achieved, whereby the body portion 80 may be partially compressed, in situ, to ensure an adequate seal. As noted previously, the body portion 80 of the insulating material 42 may therefore have some degree of compressibility, for example having up to 5 mm or even up to 25 mm of thickness compressibility (corresponding to approximately 25% of the thickness, A). For context, the body portion 80 may have a thickness, A, that is greater than or equal to 5 mm and less than or equal to 400 mm, corresponding to the typical span of the gap between the wall plate 32 and the roof covering 46 in existing building constructions. However, these dimensions are exemplary only and, again, such dimensions are not intended to be limiting on the scope of the invention. The body portion 80 may be formed of various suitable materials having a low lambda value suitable for building constructions, including a polyurethane board, aerogel, glass wool, polyester wool, mineral wool, sheep wool, or cork. For example, the body portion 80 may include compressible, fire-rated, material, such as rock fibre mineral wool, which may be selected for its thermal insulation and resilience, which is ideal for absorbing irregularities and providing effective sealing around the junction 3. The protective layer 82 may comprise waterproof or water-resistant material, including plastics materials such as polythene. In this manner, the protective layer 82 enables the insulation material 42 to be stored and installed in all weather conditions. Furthermore, the design and water-resistant nature of the protective layer 82 also allows the insulation material 42 to arrive at a building site ready for installation, and serves to ease handling and installation of the insulation material 42, as shall be described in more detail. It shall be appreciated that the protective layer 82 may be sealed to encapsulate the body portion 80 and protect the body portion 80 from environmental damage. For example, the protective layer 82 may be sealed using heat or ultrasonic sealing, an adhesive, adhesive tape, or another suitable method known to the skilled person.. The protective layer 82 described above is not intended to be limiting on the scope of the invention and, in other examples, the body portion 80 may otherwise be encapsulated by any suitable protective layer of water-resistant material, or the body portion 80 may be installed without any such protective layer. Figures 10 and 11 show an exemplary embodiment of the mounting element(s) 44. In this example, the mounting element 44 is shown to take the form of a flexible strap. However, this example is not intended to be limiting on the scope of the invention and, in other examples, the insulation unit 1 may include one or more mounting elements that extend from the first and second sides of 60, 62 of the tray 40 for attachment to the rafters 8, 10. In examples, the mounting element(s) 44 may therefore take the form of one or more rigid or flexible elements for attachment to the inner faces 64, 66 of the laterally spaced apart rafters 8, 10. For example, the mounting element(s) 44 may include a strap, cord, or rope, defining a flexible mounting element that can be tensioned and attached to the first and / or second rafters 8, 10 to support the tray 40 in the inclined position. In Figures 10 and 11, the mounting element 44 is shown as a single flexible strap having a length, I, a width, J, and a thickness, H. The width, J, and thickness, H, are not particularly limited within the scope of the invention and merely serve to provide sufficient structural integrity for securing the insulation unit 1 in position. For context, the width, J, may be at least 1 mm, but generally less than or equal to 200 mm, while the thickness, H, may be at least 0.01 mm but generally less than or equal to 10 mm. The length, I, of the mounting element 44 corresponds to the rafter spacing and includes an additional length for attachment to the rafters 8, 10. The mounting element 44 will therefore generally have a length, I, that is greater than the spacing between the first and second rafters 8, 10 and may, for example, have a length that is greater than the maximum known rafter spacing of the roof structure 4, such that the mounting element 44 can be used for any anticipated rafter spacing. The length, I, of the mounting element 44 may therefore be at least 200 mm but generally less than or equal to approximately 2500 mm. The mounting element 44 may be made from a variety of suitable materials, as shall be appreciated by the skilled person. Such materials generally have some weather resistant properties and flexibility. For example, the mounting element 44 may be made of PVC, though other materials and forming techniques may be applicable that allow mechanical fixing of the mounting element to the inside faces 64, 66 of the rafters 8, 10. It shall be appreciated that the individual elements described above may be included in a kit of parts for assembling the insulation unit 1 or the insulation unit 1 may be preassembled from such elements. For example, the tray 40, insulation material 42 and mounting element(s) 44 may be provided in a kit of parts for assembly on site. Figures 12 to 15 show the assembled insulation unit 1, as shall now be described in further detail. In assembly, the insulating material 42 is attached to the lower surface 72 of the tray 40. 20, as shown in Figure 12, and arranged so as to extend along the longitudinal axis 70 of the tray 40 for insertion around the wall plate 32. The insulating material 42 may be attached to the tray 40 by various methods that are known in the art, including by way of an adhesive, by mechanical fixing, or by a fusing method, such as ultrasonic or heat welding. For example, the protective layer 82 may be heat welded to the lower surface 72 of the tray 40 defined by the webs 76a, 76b. As shown in Figure 12, the insulating material 42 is attached to a proximal portion of the tray 40, towards the first end 56, such that the insulating material 42 is insertable through the gap between the wall plate 32 and the roof covering 46 with the first end 56 of the tray 40. For example, the insulating material 42 may be attached to the tray 40 such that a first end 92 of the body portion 80 projects beyond the first end 56 of the tray 40 in a proximal direction, for example by the distance, P, as shown in Figure 13. In examples, the insulating material 42 may project beyond the first end 56 of the tray 40, by a distance, P, of up to 1900 mm. In other examples, the first end 56 of the tray 40 may instead project beyond the first end 92 of the body portion tray 40, for example such that the dimension, P, shown in Figure 1, has a negative value, which may be up to -1900 mm. In each case, the insulation material 42 may be attached to the tray 40 such that a proximal portion of the insulating material 42 is movable relative to the tray 40 for insertion around the wall plate 32, for example being bendable and displaceable away from the tray 40 to engage the wall insulation 47. As shown in Figure 13, the insulating material 42 may also project laterally from the first and second sides 60, 62 of the tray 40, for example by the distance, M, for engagement with the inner surfaces 64 64, 66, 66 of the first and second rafters 8, 10. Once attached, the lower surface 72 of the tray 40 interfaces with the first surface 84 of the body portion 80 and the upper surface 74 of the tray 40 defines an upper surface of the insulation unit 1 for interfacing with the roof covering 46. The opposing second surface 86 of the body portion 80 defines a lower surface of the insulation unit 1 for interfacing with the wall plate 32. The mounting element 44 is attached to a distal portion of the tray 40, towards the second end 58, such that the mounting element 44 remains accessible for attachment to the rafters 8, 10 once the insulation unit 1 is inserted around the wall plate 32. The mounting element 44 may similarly be attached to the tray 40 by an adhesive, by mechanical fixing(s), and / or by a fusing method, such as ultrasonic or heat welding, though such attachment methods are provided as examples only and are not intended to be limiting on the scope of the invention. The mounting element 44 is secured so as to extend laterally from each of the first and second sides 60, 62 of the tray 40 for attachment to the first and second rafters 8, 10. Accordingly, the mounting element 44 may be attached to the tray 40 centrally with respect to the longitudinal axis 70 of the tray 40 so as to extend laterally beyond each of the first and second sides 60, 62, by a substantially equal distance, K, as shown in Figure 13. As shown in Figure 15, the mounting element 44 may be attached to a distal portion of the tray 40, for example such that the offset distance, N, from the second end 58 is less than or equal to a third of the length, F, of the tray 40, and preferably a distance less than or equal to a quarter of the length, F, of the tray 40, as shown in Figure 15. For example, the offset distance, N, may be between 0 mm and 1500 mm. Once attached, the mounting element 44 can be mechanically fixed to the inner faces 64, 66 of the first and second rafters 8, 10, for example by a fixing element such as a staple, a nail, or a screw, to secure the insulation unit 1 in an inclined position engaged with, or in close proximity to, the roof covering 46, as shall now be described in more detail. Figure 16 shows an exemplary method 100, in accordance with an embodiment of the invention, for installing the insulation unit 1 in the building construction 2 to insulate an eaves junction. As mentioned previously, the insulation unit 1 may advantageously be retrofit to an existing building construction, where the roof covering is already in place, or during assembly of the building construction, prior to fitting the roof covering. In step 102, the insulation unit 1 is inserted between the first and second rafters 8, 10 and through the gap between the roof covering 46 and the wall plate 32. In particular, the insulating material 42 is urged between the inner faces 64,66 of the first and second rafters 8, 10 and the first end 56 of the tray 40 is inserted through that gap until the insulation material 42 engages the wall insulation 47. Once the insulation material abuts against the wall insulation 47, the installer may feel increased resistance indicative of the correct insertion of the insulation unit 1. Once inserted, the insulation unit 1 fills or substantially fills the gap between the wall plate 32 and the roof covering 46, as shown in Figure 3, and the insulating material 42 extends around the eaves junction 3 to engage the wall insulation 47 on one side and the loft insulation 48 on the other side. The insulating material 42 therefore fills the gap between the wall insulation 47 and the loft insulation 48 to form a complete quilt around the junction 3, and the insulating material 42 is at least partially supported in position on top of the wall plate 32. In step 104, the distal second end 58 of the tray 40 is raised to urge the upper surface 72 of the tray 40 toward and / or into engagement with the roof covering 46. For example, the tray 40 may be raised into parallel alignment with the first and second rafters 8, 10. In step 106, the tray 40 is subsequently secured in the inclined position by attaching the mounting element 44 to the first and second rafters 8, 10. In particular, the mounting element 44 is pulled taught from the sides 60, 62 of the tray 40 to engage the inner vertical surfaces 64, 66 of the first and second rafters 8, 10, either side of the insulation unit 1, and the mounting element 44 is fixed to the rafters 8, 10 to support the tray 40 in the inclined position. For example, the mounting element 44 may be mechanically fixed by stapling each end of the mounting element 44 to a respective one of the first and second rafters 8, 10. Once installed, the tray 40 is therefore supported in engagement with or in close proximity to the roof covering 46 such that the ventilation channels 55 guides an airflow between the loft space 12 and the exterior space 52. Meanwhile, the insulation material 42 encloses the junction 3 to form a continuous length of insulation between the wall 6 and the loft space 12 of the building construction 2. In this manner, the insulation unit 1 provides for enhanced insulation around the junction 3, mitigating the formation of cold spots and related issues, whilst also providing a channel for ventilating the loft space 12. It is envisaged that embodiments of the insulation unit 1 will therefore provide for improved insulation of new and existing building constructions 2, advantageously being designed for both retrofitting to existing roof structures 4 and new building constructions. It will be appreciated by a person skilled in the art that the invention could be modified to take many alternative forms to that described herein, without departing from the scope of the appended claims. For example, the insulation unit 1 is not limited to applications at a junction, such as the example eaves junction 3 described above, for bridging a discontinuity between loft and cavity wall insulation. In other examples, the insulation unit 1 may instead be applied to a junction between a roof structure and a solid supporting wall, i.e. a wall without a cavity for insulation. In such examples, the junction may be defined where the rafters of the roof structure meet, and overhang, the supporting wall (substantially as described previously) and a layer of insulating material may be applied to an internal or an external side of the wall. A soffit or soffit box may be fitted to an overhanging portion of the roof structure and attach to the supporting wall, thereby enclosing the overhanging portion of the roof structure. As is conventional, the soffit may include vents for channelling a ventilating airflow from the exterior airspace into the loft space. In this context, the insulation unit 1 may be inserted, substantially as described previously, through a gap that exists between the supporting wall and the roof covering, such that the insulating material 42 extends around the junction and into the soffit. For example, the insulating material 42 may extend between a pair of rafters and around a wall plate at the top of the supporting wall, substantially as described previously, into the soffit. Inside the soffit, the insulating material 42 may line an external surface of the wall, enclosed by the soffit, and thereby form a continuous quilt between the loft insulation and the wall. Meanwhile, the tray 40 may act to form a continuation of the vents in the soffit and channel an airflow into the loft space. In this manner, the insulation unit serves to insulate the junction between the roof structure and the supporting wall and provide a ventilating airflow to the loft space. In other examples, the insulation unit 1 may also be installed in a raked ceiling (or a sceiling), where the ceiling includes a sloped section leading towards the wall. In this respect, the raked section is typically difficult to access, and poorly insulated, but the insulation unit 1 can be installed in substantially the same manner as for a standard eaves junction. By way of example, Figure 17 schematically illustrates another exemplary building construction 110 suitable for insulating byway of the insulation unit 1. In this example, the building construction 110 includes a wall 111 and a roof structure 112 that defines a raked ceiling 116. As in the previous example, the roof structure 112 is shown to include a plurality of inclined rafters 120 and a corresponding ceiling joist 122 connected to each rafter 120. However, in contrast to the previous example, the rafters 120 are supported directly on the wall 111 (e.g. on a wall plate 121 atop the wall 111), while the ceiling joists 122 are connected to the respective rafters 120 at an elevated height, further along the length of each rafter 120. A first ceiling panel 124 is attached to the underside of the horizontally extending ceiling joists 122 and a second ceiling panel 126 is attached to the underside of the rafters 120, extending between the wall 111 and the joists 122. The second ceiling panel 126 therefore extends at an inclined or raked angle and defines a raked section of the ceiling 116. In other examples it shall be appreciated that a single suitably shaped ceiling panel may attached to the rafters 120 and the joist 122 to define the raked ceiling 116 instead. As in the previous example, loft insulation (not shown) is typically provided in a loft space 128 above the first ceiling panel 124 and between the ceiling joists 122. However, space is very restricted beyond the junction between the rafters 120 and the ceiling joists 122, as a roof covering (not shown) is supported on the rafters 120 and restricts access to the raked section of the ceiling 116. As a result, there is frequently a discontinuation of the insulation at said junction and / or at the junction between the rafters 120 and the supporting wall 111. The discontinuation(s) can permit cold bridging via the junction(s), or the raked section of the ceiling 116 and lead to the formation of cold spots on the interior surfaces of the building construction 110. However, the insulation unit 1 may advantageously be installed in the building construction 110 to insulate each junction, along with the raked section of the ceiling 116, and form one or more ventilation channels for ventilating the loft space 128. In particular, the insulation unit 1 may be inserted between an adjacent pair of the rafters 120 and through the gap between the roof covering (not shown) and the opposing first and second ceiling panels 124, 126. The first end 56 of the tray 40 may therefore be inserted through that gap until the insulation material 42 passes along the entire length of the raked section of the ceiling 116 and, in some case, may further extend over the wall plate 121 atop the wall 111. For example, the insulation unit 1 may be inserted to the extent that the insulation material 42 passes into a soffit (not shown) attached to the overhanging portion of the roof structure 112 or to the extent that the insulation material 42 engages a respective insulation layer of the wall 111. In each case, the insulation unit 1 therefore extends along the entire length of the second ceiling panel 126 and provides additional insulation to the raked section. Meanwhile, the opposing distal end of the insulation unit 1 projects into the loft space 128, where the insulation material 42 engages the loft insulation (not shown). Once inserted, the insulation unit 1 therefore fills or substantially fills the gap between the roof covering and the underlying ceiling panels 126, 128 and the insulating material 42 further extends around each junction to form a complete quilt between the wall 111 and the loft space 128. Thereafter, the distal second end 58 of the tray 40 may be raised, if necessary, to urge the upper surface 72 of the tray 40 toward, and / or into engagement, with the roof covering. For example, the tray 40 may be raised into parallel alignment with the adjacent rafters 120 and the tray 40 is then securable in the inclined position by attaching the mounting element 44 to the adjacent rafters 120. In particular, the mounting element 44 may be pulled taught from the sides 60, 62 of the tray 40 to engage inner vertical surfaces of the adjacent pair of rafters 120, either side of the insulation unit 1, and the mounting element 44 may be fixed to the rafters 120 to support the tray 40 in the inclined position. Once installed, the tray 40 is therefore supported in engagement with, or in close proximity to, the roof covering such that the ventilation channels 55 guide an airflow between the loft space 128 and an exterior space. Meanwhile, the insulation material 42 extends along the raked section of the ceiling 116 and around the respective junctions, at either end, to form a continuous length of insulation between the wall 111 and the loft space 128 of the building construction 110. In this manner, the insulation unit 1 provides for enhanced insulation of the raked ceiling 116, mitigating the formation of cold spots and related issues, whilst also providing a channel for ventilating the loft space. Again, it shall be appreciated that the insulation unit 1 may advantageously be retrofit to an existing building construction of the type shown in Figure 17, where the roof covering is already in place, or during assembly of the building construction, prior to fitting the roof covering.

Claims

1. An insulation unit for installation in a building construction comprising an adjacent pair of rafters supported on a wall, the insulation unit comprising:a tray having:an upper surface and an opposing lower surface;a length extending along a longitudinal axis from a proximal first end to a distal second end, anda width extending along a transverse axis from a first side to an opposing second side;insulation material attached to the lower surface of the tray and extending along the longitudinal axis for insertion around an edge of the wall so as to extend between first and second insulation spaces either side of the edge; and one or more mounting elements extending away from the first and second sides of the tray, along the transverse axis, for engagement with first and second opposing surfaces of the adjacent pair of rafters,wherein the one or more mounting elements are attachable to the first and second opposing surfaces of the rafters to support the tray in an inclined position for forming a ventilation channel between the tray and a covering supported on the rafters.

2. An insulation unit according to claim 1, wherein the insulation material is attached to a proximal portion of the tray and the one or more mounting elements extend from a distal portion of the tray.

3. An insulation unit according to claim 2, wherein the one or more mounting elements extend from a position at the second end of the tray or a position that is offset from the second end of the tray by a distance less than or equal to a third of the length of the tray, optionally, a distance less than or equal to a quarter of the length of the tray.

4. An insulation unit according to any preceding claim, wherein the one or more mounting elements comprise a flexible mounting element, the flexible mounting element being tensible for attachment to the first and / or second opposing surfaces of the rafters to support the tray in the inclined position.

5. An insulation unit according to claim 4, wherein the flexible mounting element is a strap, cord, or rope, for attachment to the first and / or second opposing surfaces of the rafters.

6. An insulation unit according to claim 4 or claim 5, wherein the one or more mounting elements comprise a pair of flexible mounting elements, each flexible mounting element extending from a respective one of the first and second sides of the tray for attachment to a respective one of the first and second opposing surfaces of the rafters.

7. An insulation unit according to any preceding claim, wherein the insulation material extends along the longitudinal axis from a first end portion to a distal second end portion.

8. An insulation unit according to claim 7, wherein the first end portion projects beyond the first end of the tray in a proximal direction.

9. An insulation unit according to claim 7, wherein the first end of the tray projects beyond the first end portion of the insulation material in a proximal direction.

10. An insulation unit according to claim 9, wherein the first end of the tray projects beyond the first end portion of the insulation material by a length less than or equal to 1.9 m.

11. An insulation unit according to any of claims 7 to 10, wherein the first end portion of the insulating material is movable relative to the tray for insertion around the edge into the first insulation space while the second end portion of the insulating material extends into the second insulation space.

12. An insulation unit according to any preceding claim, wherein the insulation material extends along the transverse axis beyond the first and / or second sides of the tray.

13. An insulation unit according to any preceding claim, wherein the insulation material comprises a compressible body of insulating material, optionally, wherein the body is made of at least one of: a polyurethane board; aerogel; glass wool; polyester wool; mineral wool, such as a rock fibre mineral wool; sheep wool; or cork.

14. An insulation unit according claim 13, where in the body has a substantially uniform thickness, orthogonal to the longitudinal and transverse axes, of less than or equal to 0.4m.

15. An insulation unit according to claim 13, wherein the body has a substantially uniformthickness, orthogonal to the longitudinal and transverse axes, greater than or equal to 5 mm.

16. An insulation unit according to any of claims 13 to 15, wherein the insulation material comprises a protective layer encapsulating the body, the protective layer being water-resistant or waterproof material,17. An insulation unit according to any preceding claim, wherein the insulating material is attached to the tray by bonding, such as ultrasonic welding or heat welding; adhesive; and / or mechanical fixing.

18. An insulation unit according to any preceding claim, wherein the one or more mounting elements are attached to the tray by bonding, such as ultrasonic welding or heat welding; adhesive; and / or mechanical fixing.

19. An insulation unit according to any preceding claim, wherein the tray is a ventilation tray comprising a plurality of air guiding formations on the upper surface for guiding an airflow along the ventilation channel.

20. A kit of parts comprising:a tray;insulation material; andone or more mounting elements;for forming an insulation unit according to any preceding claim21. A building construction comprising:a pair of rafters supported on a wall; andan insulation unit according to any of claims 1 to 19;wherein the insulation material extends around an edge of the wall between first and second insulation spaces either side of the edge; andthe one or more mounting elements are attached to opposing surfaces, defined by the pair of rafters, to support the tray in an inclined position.

22. A building construction according to claim 21, further comprising a covering supported on the rafters, wherein the tray is supported in the inclined position to form a ventilation channel between the tray and the covering.

23. A building construction according to claim 22, wherein the insulation material fills a space between the wall and the tray, supporting the tray in the inclined position.

24. A building construction comprising:a pair of rafters supported on a wall;a pair of joists, each joist being connected to a respective one of the pair of rafters at an elevated height relative to the wall to define a raked ceiling; andan insulation unit according to any of claims 1 to 19 arranged between the pair of rafters for insulating the raked ceiling, the one or more mounting elements being attached to opposing surfaces, defined by the pair of rafters, to support the tray in an inclined position.

25. A building comprising:an insulation unit according to any of claims 1 to 19; ora building construction according to any of claims 21 to 24.

Images