A glazing bead assembly

Abstract

A glazing bead assembly 14 for retaining a glazing unit 18 within a frame 12. The glazing bead assembly comprises an elongate bead body comprising an interior support member 20 formed from a first mat

Description

FIELD The present teachings relate to a glazing bead assembly for a fenestration unit, and a fenestration unit comprising said glazing bead assembly. BACKGROUND Modern fenestration units typically comprise a frame assembly, into which a panel, such as a glass pane, or a sealed double glazing unit, is inserted in a direction generally normal to the plane of the panel. Typically, such frame assemblies are pre-assembled prior to the panel being inserted. A glazing bead is then secured to the frame assembly after the panel has been inserted into the frame assembly, along with a gasket, for securing and sealing said panel within the frame assembly. Frames for a fenestration unit can be manufactured from a variety of materials, for example aluminium and uPVC. Commonly, the glazing bead and the frame are manufactured using the same material, therefore the use of uPVC bead with aluminium systems is generally not considered acceptable in the fenestration industry and is generally not cost effective after essential spray painting / powder coating to match the colour and gloss levels of the aluminium frames is carried out. This means aluminium windows commonly use an aluminium glazing bead to retain the glazing unit. However, aluminium is relatively lacking in resilience and has a high level of thermal conductivity. It is typical for aluminium beads to be a loose fit within a channel of a frame, and to be secured in place by fitting a gasket between the bead and the fenestration unit to bias the bead into engagement within the frame. If the gasket is not installed correctly, a tight, uniform and durable seal cannot be achieved. This can lead to poor thermal insulation and weather sealing. In addition, this requires additional labour at the installation stage, adding to the total cost of installation. The present teachings seek to overcome or at least mitigate one or more of the problems associated with the prior art. SUMMARY A first aspect of the teachings provides a glazing bead assembly for retaining a glazing unit within a frame member, the glazing bead assembly comprising: an elongate bead body comprising an interior support member formed from a first material and an exterior support member formed from a second material different from the first material; wherein the interior support member may comprise a plurality of walls defining an enclosed internal volume therebetween extending along an elongate length thereof; wherein the interior support member comprises a recess or protrusion located on one of the plurality of walls of the interior support member, wherein the recess or protrusion may be configured to engage the other of a recess or protrusion located on an interior surface of the exterior support member so as to mechanically fasten the interior support member to the exterior support member to form the bead body; wherein the interior support member and the exterior support member may each comprise a respective first or second frame engagement formation configured to engage a respective first or second complementary bead engagement formation of the frame member, in use. Advantageously, providing a glazing bead assembly with an elongate bead body comprising interior and exterior support members enables customisation of the bead, for example customisation of the structural strength, flexibility and aesthetics of the interior and exterior support members whilst minimising the number of different components required for different custom installations. Providing an interior support member with an enclosed internal volume enables the glazing bead assembly to flex during an impact thereto, for example an impact to the outside of the fenestration unit to gain unauthorised access thereto (or in testing to simulate such attempts at unauthorised access), without permanently deforming, thereby increasing the durability of the glazing bead assembly and in meeting or exceeding standards for the security of the fenestration unit. Additionally, providing an enclosed internal volume improves the thermal performance of the glazing bead and reduces the amount of material used in manufacture comped to a solid interior support member. Optionally, the protrusion of the exterior support member or the interior support member comprises a tongue. Optionally, the tongue is mounted to the recess using a push-fit arrangement. Advantageously, the push-fit engagement of the tongue and recess enables the interior support member to be releasably mounted to the exterior support member with minimal damage to the interior or exterior support member. The push-fit arrangement enables simple fastening and separation of parts upon installation and removal and requires a fewer number of parts than alternative fastening mechanisms, making it simpler and more convenient for the fitter. Optionally, the tongue defines a leading end and a trailing end with respect to a direction of insertion of the tongue into the recess. Optionally, a width of the tongue decreases from the trailing end to the leading end. Advantageously, the decrease in width of the tongue creates a wedging effect as the tongue is inserted into the recess, thereby improving ease of insertion and removal of the tongue into and from the recess. Optionally, the protrusion comprises a neck portion extending between the interior surface of the exterior support member and the tongue. Optionally, an opening of the recess engages the neck portion to retain the tongue within the recess, in use. Advantageously, engagement of the neck portion helps to prevent the tongue from easily disengaging from the recess. As a width of the neck portion may be less than a width of the trailing end of the tongue, engagement of the neck portion helps to reduce the likelihood of the trailing end moving past the opening and out of the recess. Optionally, the glazing bead assembly defines a height configured to extend parallel to a pane of the glazing unit, in use. Optionally, a length of the protrusion located in the recess is less than two thirds of the height of the glazing bead assembly, optionally less than half the height of the glazing bead assembly. Advantageously, providing a length of protrusion which is less than half or less than two thirds the height of the glazing bead assembly helps to increase overall flexibility of the glazing bead assembly whilst reducing amount of material used. Additionally, the thermal performance is improved by providing an air gap or bridge in the internal volume. Optionally, the first frame engagement formation is a protrusion. Optionally, the protrusion is configured to be received in the first bead engagement formation of the frame member, in use. Optionally, the protrusion extends in a first direction configured to extend towards the first bead engagement formation, in use, and in an opposing second direction configured to extend away from the first bead engagement formation, in use. Advantageously, this is a simple means of securing the glazing bead assembly within the frame member to aid the glazing bead installation and removal processes and retain the glazing unit within the frame. Having the protrusion on the glazing bead assembly doesn't act as a barrier to fitting of the glazing unit, as it may if the protrusion was on the frame member. Advantageously, providing a protrusion which extends in two opposing directions enables both ends of the protrusion to engage the first bead engagement formation depending on the orientation of the glazing bead assembly, thereby increasing versatility of the glazing bead assembly. Optionally, the interior support member comprises a leg extending therefrom in a direction away from the internal volume. Optionally, the protrusion is located on the leg, optionally at a distal end of the leg. Advantageously, the leg provides a surface on which to locate the first engagement formation and provides support for the bead body with respect to the channel of the frame member. Optionally, the interior support member is attachable to the exterior support member in a first orientation and in a second orientation such that the glazing bead assembly is configured to be reversibly mountable to the first engagement formation of the frame member, in use. Advantageously, providing a glazing bead assembly which is reversible helps to increase the versatility of the glazing bead assembly for use with frame members of differing widths or configurations, and / or where the glazing panel has a different relative position to the frame member corresponding to the first and second orientations. This increases versatility of the glazing bead assembly, and may decrease manufacturing costs because the same glazing bead assembly can be used for different types of frame member. Optionally, the protrusion defines a first end and an opposing second end. Optionally, in the first orientation the first end of the protrusion is a leading end with respect to a direction of insertion of the protrusion into the first bead engagement formation of the frame member and in the second orientation the second end of the protrusion is the leading end with respect to the direction of insertion of the protrusion into the first bead engagement formation of the frame member. Advantageously, providing a glazing bead assembly whereby the interior support member is attachable to the exterior support member in first and second orientations helps to increase the versatility of the glazing bead assembly for use with frame members of differing widths or configurations corresponding to the first and second orientations. This increases versatility of the glazing bead assembly, and may decrease manufacturing costs because the same glazing bead assembly can be used for different types of frame member. Optionally, when in the first orientation, a maximum width between one of the plurality of side walls of the interior support member and an exterior surface of the exterior support member is greater than a maximum width between one of the plurality of sidewalls and the exterior surface of the exterior support member in the second orientation. Advantageously, providing different maximum widths enables the glazing bead assembly to be assembled to frame members with differing widths, for example differing widths between the glazing unit and a side of the frame member remote from the glazing unit. This increases versatility of the glazing bead assembly, and may decrease manufacturing costs because the same glazing bead assembly can be used for different types of frame member. Optionally, in the second orientation, the interior support member is orientated approximately 180° with respect to the first orientation. Advantageously, this simplifies mounting of the interior support member to the exterior support member in the first and second orientations and enables an increase in the maximum widths in the first and second orientations. Optionally, the recess is located on the interior support member and the protrusion is located on the exterior support member. Advantageously, providing the protrusion on the exterior support member helps to enables a greatervariety of profiles of the exterior support member without obstructing the recess. Additionally, providing the protrusion on the exterior support member is simpler due to the more restrictive design requirements of the exterior support member as it is visible, for example planar surfaces. Optionally, the recess is located on one of the plurality of walls and extends into the internal volume, and wherein the plurality of walls enclose the internal volume to define a substantially U-shaped cross-sectional shape of the internal volume. Advantageously, the recess provides space for the interior support member to receive the protrusion within the internal volume, thereby providing a compact design. Additionally, the U-shaped internal volume is flexible and therefore able deform upon impact without permanent damage to the glazing bead assembly. Thermal performance may also be improved through the glazing bead assembly by providing the U-shaped recess. Optionally, the plurality of walls of the interior support member comprise opposing sidewalls extending between an uppermost and a lowermost wall, optionally wherein the opposing sidewalls are substantially parallel. Advantageously, this shape of interior support member is simple to manufacture and helps to conform to a shape of the frame member, thereby providing a compact arrangement. Optionally, the recess or protrusion and the first frame engagement formation are located on opposing walls of the plurality of walls of the interior support member such that the internal volume is located between the recess or protrusion and the first frame engagement formation. Advantageously, this arrangement provides separation between the mounting of the interior support member to the exterior support member and the mounting of the glazing bead assembly to the frame member, thereby preventing said mounting arrangements from obstructing one another. Optionally, the recess or protrusion is located on the uppermost wall of the interior support member and wherein the first frame engagement formation is located on the lowermost wall of the interior support member and extends in a direction away from the internal volume. Advantageously, providing the first support engagement formation on the uppermost wall helps to prevent it from obstructing mounting of the glazing bead assembly to the frame member. Optionally, the internal volume occupies a majority of a total cross-sectional area of the interior support member. Advantageously, this arrangement of the internal support member helps to increase flexibility of the interior support member, thereby enabling the glazing bead assembly to flex upon impact. Additionally, the thermal performance of the glazing bead assembly is improved by creating an air bridge or gap in the internal volume. Optionally, at least one gasket is mounted to the interior support member, optionally wherein the gasket is a bubble gasket. Advantageously, the gasket helps to retain the glazing unit between the frame member and glazing bead assembly, and improves sealing across the frame member. Optionally, the at least one gasket is coextruded with the interior support member. Advantageously, this removes the need for a separate gasket, thereby reducing the number of steps in the manufacturing process. This means fewer parts have to be assembled when the glazing unit is installed and removed. Optionally, the coextruded gasket is formed using a thermoplastic elastomer (TPE). Advantageously, using a thermoplastic elastomer (TPE) gasket enables the gasket to be coextruded with the structural support member due to its ability to chemically bond to plastics, which simplifies the manufacturing process. TPE also has the advantage of being lower cost than silicone, which is commonly used to manufacture gaskets. Optionally, the interior support member is formed from a material of greater flexibility to the exterior support member. Advantageously, this enables the properties of both flexibility and structural to be optimised, whilst allowing for customisation of the glazing bead assembly depending on aesthetic considerations. Optionally, the interior support member is formed form uPVC. Advantageously, as uPVC is resilient, this eases installation and removal of the glazing bead assembly whilst minimising risk of damage to the glazing bead assembly or frame member. Additionally, the flexibility of the glazing bead assembly is increased, thereby enabling the glazing bead assembly to flex upon impact. Optionally, the exterior support member is formed from an aluminium alloy. Advantageously, this may help to match the material of the exterior support member and of the frame member to provide a uniform performance. According to a further aspect of the present teachings, there is provided a glazing bead assembly for retaining a glazing unit within a frame member, the glazing bead assembly comprising: an elongate bead body comprising an interior support member formed from a first material and an exterior support member formed from a second material different from the first material; wherein the interior support member comprises a first support engagement formation configured to engage a complementary second support engagement formation located on an interior surface of the exterior support member so as to mechanically fasten the interior support member to the exterior support member to form the bead body; wherein the interior support member and the exterior support member each comprise a respective first or second frame engagement formation configured to engage a respective first or second complementary bead engagement formation of the frame member, in use; and wherein the interior support member is attachable to the exterior support member in a first orientation and in a second orientation such that the glazing bead assembly is configured to be reversibly mountable to the first bead engagement formation of the frame member, in use. Advantageously, providing a glazing bead which is reversible helps to increase the versatility of the glazing bead for use with frame members of differing widths or configurations, and / or where the glazing panel has a different relative position to the frame member corresponding to the first and second orientations. This increases versatility of the glazing bead assembly, and may decrease manufacturing costs because the same glazing bead assembly can be used for different types of frame member. According to a further aspect of the present teachings, there is provided a fenestration unit for installation within an opening, the fenestration unit comprising: at least one frame member comprising first and second bead engagement formations; a glazing bead assembly according to a previous aspect fastened to the bead engagement formations of the frame member so as to define a groove therebetween; a glazing unit positioned within a portion thereof the groove and retained in the groove by the glazing bead assembly. Advantageously, providing a glazing bead assembly with an elongate bead body comprising interior and exterior support members enables customisation of the bead, for example customisation of the structural strength, flexibility and aesthetics of the interior and exterior support members. Providing an interior support member with an enclosed internal volume enables the glazing bead assembly to flex during an impact thereto, for example an impact to the outside of the fenestration unit to gain unauthorised access thereto, without permanently deforming, thereby increasing the durability of the glazing bead assembly. Additionally, providing an enclosed internal volume improves the thermal performance of the glazing bead and reduces the amount of material used in manufacture comped to a solid interior support member. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 is a front view of a fenestration unit having a glazing bead assembly according to an embodiment of the present teachings; Figures 2A and 2B are a cross-sectional views of embodiments of fenestration units on the plane z-z of Figure 1; Figures 3A and 3B are cross-sectional views of the glazing bead assembly of Figure 2A in an assembled state and a disassembled state respectively; Figure 4 is a cross-sectional view of the glazing bead assembly of Figure 2B; Figure 5 is a cross-sectional view of a method of assembling the fenestration unit of Figure 2A; Figure 6 is a cross-sectional view of an alternative embodiment of a glazing bead assembly for the fenestration unit of Figure 2A; Figure 7 is a cross-sectional view of an alternative embodiment of a glazing bead assembly for the fenestration unit of Figure 2B; and Figure 8 is a cross-sectional view of a method of assembling the glazing bead assembly of Figure 6 to the fenestration unit of Figure 2A. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 shows a fenestration unit according to an embodiment of the present teachings generally indicated at 10. The fenestration unit 10 includes a frame 12 with a glazing bead assembly 14 mounted thereto. The fenestration unit 10 is suitable for a window, door or other type of fenestration such as a vent or cladding panel. The frame 12 is configured to receive and support a pane or panel, such as a pane of glass, a double glazing unit or a triple glazed sealed unit, or a panel of wood, aluminium or other suitable material. In the embodiment shown in Figure 1, a double glazing unit 18 is received and supported by the frame 12. In alternative embodiments, the pane or panel may be an alternative glazing unit, for example triple glazing or opaque panels, for example for doors, may be used. Fenestration units 10 of this type are typically used in external walls of domestic and commercial buildings. It is therefore desirable that the fenestration unit 10 meets requirements for thermal insulation, sealing against water ingress, draughts etc. Typically, the frame 12 is a metallic frame 12 constructed from four frame members 12a-d arranged at right angles. A metallic frame as described here may include features or components of some non-metallic or composite material, such as plastics material or wood. In particular, the frame members 12a-d may include external and internal aluminium profiles 13a, 13b, which provide structural strength to the frame 12, with a thermal break 15 of plastics or foam material sandwiched therebetween. The frame members 12a-d are connected by mitre joints, for example by 45° mitre joints, however in alternative embodiments the frame members 12a-d may have ends finished with right angles. Glazing bead assemblies 14 are fitted to the frame 12 with ends finished at right angles, as illustrated in Figure 1. The glazing bead assemblies 14 are described in more detail below. It shall be appreciated that in alternative embodiments, the glazing bead assemblies 14 may include abutting mitred ends, for example 45° mitres. The mitres of the glazing bead assemblies 14 may match the mitres of the end of the frame members 12a-d. Typically, the frame 12 is an aluminium frame. The frame 12 of this embodiment comprises a 6063T6 aluminium alloy. However, it shall be appreciated that any other suitable material may be used. In one alternative, the frame 12 is of some other suitable material, such as some other 6063 series aluminium alloy, or a 6060 series aluminium alloy. It shall be appreciated that the term 'exterior' refers to the area outside of the fenestration unit 10, and the term 'interior' refers to the area enclosed between the frame member 12d and the glazing unit 18. Therefore, for example, 'exterior side' refers to the side closest to the outside of the fenestration unit 10, and 'interior side' refers to the side closest to the area enclosed between the frame member 12d and the glazing unit 18. The fenestration unit 10 may comprise a fixed or moveable sash. In this embodiment, the sash is omitted and the glazing unit 18 is installed directly into the outer frame 12. The teachings are however applicable to embodiments in which there are sliding or pivoting sashes. Figure 2A shows a cross-sectional view of a portion of the fenestration unit 10 on the plane z-z in which the glazing bead assembly 14 is configured to retain the glazing unit 18 via a gasket 24. As such, Figure 2A shows the frame member 12d and glazing bead assembly 14 which is mounted thereto. Whilst only one glazing bead assembly 14 is illustrated in Figure 2A, it shall be appreciated that at each of the four sides of the frame 12 there may be a glazing bead assembly 14 of substantially the same configuration. Therefore, for reasons of conciseness and brevity, only glazing bead assembly 14 shall be described herein. It shall be appreciated that the height direction is taken to be the direction which extends substantially parallel to a pane of the glazing unit 18 and transverse to the longitudinal axis of the frame member 12d when the fenestration unit 10 is assembled. The width direction is taken to be the direction which extends transverse to the pane of the glazing unit 18 when the fenestration unit 10 is assembled. In this embodiment, the frame member 12d includes an opposing gasket 25 mounted to an upstand or abutment 11 on the opposite side of the glazing unit 18 to the glazing bead assembly 14. The opposing gasket 25 is fitted to the abutment 11 prior to installation of the glazing unit 18. The opposing gasket 25 is manufactured from a rubber-like material, in particular Thermoplastic Elastomer (TPE) or EDPM, meaning upon installation of the glazing unit 18, the opposing gasket 25 compresses due to the force exerted by the glazing unit 18. The use of the opposing gasket 25 fitted into abutment 11 on a first side of the glazing unit 18, and the gasket 24 on a second side of the glazing unit 18, centralises the glazing unit 18 within the fenestration unit 10 because both gaskets 24, 25 are configured to compress by a similar amount relative to each other. This creates an effective seal and correctly aligns the glazing unit 18 through the compression of the gaskets 24, 25, whilst enabling the retention of the glazing unit 18 within the frame 12. The frame member 12d includes first and second bead engagement formations 40, 42 which extend along a longitudinal axis of the frame member 12d. The glazing bead assembly 14 is fastened to the first and second bead engagement formations 40, 42 of the frame member 12d so as to define a groove 17 therebetween. The glazing unit 18 is positioned within a portion thereof the groove 17 and retained in the groove 17 by the glazing bead assembly 14. The thermal break 15 at least partially defines a base wall of the groove 17. The external profile 13a defines a first sidewall of the groove 17, and the glazing bead assembly 14 defines an opposing second sidewall of the groove 17. It shall be appreciated that the glazing bead assembly 14 may be beaded to the internal or external side of a building based on the application. The external profile 13a is located on the external side of the fenestration unit 10, i.e. the side which is outside of the building, and includes the abutment 11. The internal profile 13b is located on the internal side of the fenestration unit 10, i.e. the side which is inside the building, and is used to fasten the glazing bead assembly 14 thereto. The first bead engagement formation 40 is located on the thermal break 15 in the embodiment of Figure 2A. The first bead engagement formation 40 is a female engagement formation 40. Having the female formation 40 on the frame member 12d doesn't act as a barrier to fitting the glazing unit 18. In particular, the first bead engagement formation 40 is a channel 40 extending along an elongate length of the thermal break 15. The channel 40 extends into the thermal break 15 in a direction transverse to the pane of the glazing unit 18. Put another way, the channel 40 extends into the thermal break 15 in a direction towards the abutment 11. The thermal break 15 and the internal profile 13b meet to define a substantially planar surface. The substantially planar surface defines a lowermost wall of the first engagement formation 40, i.e. the first channel 40. It shall be appreciated that in alternative embodiments, the first bead engagement formation 40 may be located on an alternative part of the frame member 12d, for example on the internal profile 13b. The second bead engagement formation 42 is located on the internal profile 13b. The second bead engagement formation 42 is a male engagement formation 42. As illustrated in Figure 2A, the second bead engagement formation 42 is a wall 42 extending along an elongate length of the internal profile 13b. The wall 42 extends from an exterior wall of the internal profile 13b in a direction towards the glazing unit 18. In the embodiment shown in Figure 2A, the wall 42 extends parallel to the axis transverse to the pane of the glazing unit 18 towards the glazing unit 18, however in alternative embodiments the wall 42 may extend at an angle relative to the transverse axis. The wall 42 includes a distal end which is remote from the exterior wall of the interior profile 13b, and the distal end engages the glazing bead assembly 14. It shall be appreciated that in alternative embodiments, any suitable arrangement of bead engagement formations 40, 42 may be provided. Furthermore, it shall be appreciated that more than two bead engagement formations may be provided. The frame member 12d defines a width wi extending between the first bead engagement formation 40 and the second bead engagement formation 42 in a direction transverse to the pane of the glazing unit 18 and a width w3 extending between the glazing unit 18 and an exterior surface 22a of the glazing bead assembly 14. The width wi may be in the range 9mm to 39mm, optionally in the range 15mm to 33mm, for example in the range 19mm to 29mm. In the embodiment shown in the Figures, the width wi is approximately 24mm. The width w3 may be in the range 21mm to 51mm, optionally in the range 27mm to 45mm, for example in the range 31mm to 41mm. In the embodiment shown in the Figures, the width w3 is approximately 36mm. It shall be appreciated that the width of the frame member 12d may be varied depending on design requirements of the fenestration unit 10, for example size, function of the fenestration unit or aesthetics. Figure 2B shows an alternative embodiment of a frame member 112 according to an embodiment of the present teachings to which the glazing bead assembly 14 may be assembled. Like parts with the embodiment of Figure 2 are labelled with the prefix "1". It shall be appreciated that the teachings described above in relation to Figure 2A are also applicable to the embodiment of Figure 2B. The differences between the frame member 12d of Figure 2A and the frame member 112d of Figure 2B will be described hereafter. The frame member 112d defines a width w2 extending between the first bead engagement formation 140 and the second bead engagement formation 142 and a width w4 extending between the glazing unit 118 and the exterior surface 22a of the glazing bead assembly 14. The width w2 is substantially the same as the width wi. The width w4 is less than the width w3. This is because the upstand 111 has been moved towards the internal profile 113b in the embodiment of Figure 2B, meaning that the glazing unit 118 has been moved towards the internal profile 113b and the width w4 is reduced. The width w2 may be in the range 9mm to 39mm, optionally in the range 15mm to 33mm, for example in the range 19mm to 29mm. In the embodiment shown in the Figures, the width w2 is approximately 24mm.. The width w4 may be in the range 13mm to 43mm, optionally in the range 19mm to 37mm, for example in the range 23mm to 33mm.. In the embodiment shown in the Figures, the width w4 is approximately 28mm. Figures 2A and 2B therefore illustrate two different embodiments of frame member 12d, 112d with which the glazing bead assembly 14 may be used. Figures 3A, 3B and 4 show detailed cross-sectional views of the glazing bead assembly 14 of Figures 2A and 2B. The glazing bead assembly 14 is shown in a first configuration in Figures 3A and 3B in an assembled and a disassembled state respectively, and in a second configuration in Figure 4. It shall be appreciated that when mounted to the frame member 12d of Figure 2A, the glazing bead assembly 14 is in the first configuration of Figures 3A and 3B, and when mounted to the frame member 112d of Figure 2B, the glazing bead assembly 14 is in the second configuration of Figure 4. As such, the glazing bead assembly 14 is a reversible glazing bead assembly 14 which is mountable to the frame members 12d, 112d in a first configuration and a second configuration, as is described in more detail below. This enables the glazing bead assembly 14 in its basic form to be mounted to frame members 12d, 112d of differing widths (i.e. differing widths w3, w4 between the glazing unit 18 and the exterior surface 22a of the glazing bead assembly 14), thereby increasing versatility of the glazing bead assembly 14, and minimising the number of individual parts required for bead assemblies 14 of differing widths. The glazing bead assembly 14 includes an elongate bead body 20, 22 having an interior support member 20 and an exterior support member 22. In the embodiment shown in the Figures, the glazing bead assembly 14 also includes a gasket 24, as described above, for sealingly engaging the glazing unit 18. The respective cross-sections of the interior support member 20, exterior support member 22 and the gasket 24 extend along their respective longitudinal axes. In the embodiment of Figures 3A and 3B, the interior support member 20, exterior support member 22 and the gasket 24 are of constant cross-section i.e. formed in a suitable extrusion process. However, in alternative embodiments the interior support member 20, exterior support member 22 and gasket 24 may have an alternative geometry, e.g. a nonconstant cross-section, for example from post processing. In the embodiments shown in Figure 3A and 3B, the gasket 24 is coextruded with the interior support member 20, however in alternative embodiments the gasket 24 may be formed separately and mounted to the glazing bead assembly 14, e.g. via adhesive, heat welding or a push-fit mechanical connection. The interior support member 20 and the exterior support member 22 are formed from different materials. In particular, the interior support member 20 may be formed from a material of greater flexibility than the exterior support member 22. This enables the properties of both flexibility and structural strength to be optimised, whilst allowing for customisation of the glazing bead assembly 14 depending on aesthetic considerations. For example, providing an interior support member 20 which is more flexible enables the glazing bead assembly 14 to flex and dissipate energy during an impact thereto, for example an impact to the outside of the fenestration unit to gain unauthorised access thereto, without permanently deforming, thereby increasing durability of the glazing bead assembly 14. Providing an exterior support member 22 of a less flexible material may enable a material of the exterior support member 22 to be matched to that of the frame member 12d, which may be formed of a material of lower flexibility, thereby providing a uniform frame assembly 12 and improving aesthetics of the frame assembly 12. The increase in flexibility of the interior support member 20 compared to the exterior support member 22 may be due material choice, geometry of the interior support member 20 and / or the exterior support member 22, or a combination thereof. For example, the interior support member 20 may have a thinner walls than the exterior support member 22 in order to provide a greater flexibility of the interior support member 20 and / or the flexural modulus of the two materials may differ. The flexural modulus of the exterior support member 22 may be higher than for the interior support member 20. In the embodiment of Figure 3A, the interior support member 20 is formed from uPVC and the exterior support member 22 is formed from an aluminium alloy. As uPVC is relatively resilient, this eases the installation and removal of the glazing bead assembly 14 whilst minimising the risk of damage to the glazing bead assembly 14 or the frame member 12d. The coextruded gasket 24 is formed using a thermoplastic elastomer (TPE). In other embodiments the interior support member may be made of other suitable plastics material such as polyamide. The interior support member 20 includes a plurality of walls 26a-d defining an enclosed volume 28 extending along an elongate length thereof, a support engagement formation 30 located on one of the plurality of walls 26a-d of the interior support member 20 and extending into the internal volume 28 and a first frame engagement formation 32 configured to engage the first bead engagement formation 40 of the frame member 12d, in use, as illustrated in Figure 2A. As illustrated in Figure 3A, the plurality of walls 26a-d includes opposing sidewalls 26a, 26b. The opposing sidewalls 26a, 26b extend between an uppermost wall 26c and a lowermost wall 26d. It shall be appreciated that the term "uppermost" in this context is taken to mean the wall 26a-d which is located furthest from the frame member 12d in the height direction, in use, and the term "lowermost" is taken to mean the wall 26a-d which is located closest to the frame member 12d in the height direction, in use. The opposing sidewalls 26a, 26 are substantially parallel. A portion of the uppermost wall 26c is substantially parallel to the lowermost wall 26d. The plurality of walls 26a-d enclose the internal volume 28 to define a substantially U-shaped cross-sectional shape of the internal volume 28. In particular, when the first support engagement formation 30 is a recess 30 located on the uppermost wall 26a, the recess 30 extends into the internal volume 28 to define the U-shaped cross-section. The remainder of the uppermost wall 26c (i.e. the part adjacent the recess 30) is parallel with the lowermost wall 26d. In the embodiment of Figures 3A and 3B, the recess 30 is located substantially centrally with respect to a central longitudinal axis a-a of the interior support member 20, however in alternative embodiments the recess 30 may be offset therefrom. In the embodiment shown in Figure 3A, the central longitudinal axis a-a extends between the uppermost and lowermost walls 26c, 26d of the interior support member 20. As illustrated in Figure 3A, the internal volume 28 occupies a majority of a total cross-sectional area of the interior support member 22. This helps to increase flexibility of the interior support member 20, thereby enabling the glazing bead assembly 14 to flex and dissipate energy upon impact, for example an impact to the outside of the fenestration unit to gain unauthorised access thereto. Additionally, the thermal performance of the glazing bead assembly 14 is improved by creating an air pocket or chamber in the internal volume 28. The internal volume 28 in the embodiment of Figure 3A is a hollow or empty void, i.e. there is nothing in the internal volume 28. It shall be appreciated that in alternative embodiments, the internal volume 28 may be filled with a thermally insulating material, and / or may include ribs or struts extending thereacross. The first support engagement formation 30 in the embodiment of Figure 3A is a female engagement formation 30. In particular, the female engagement formation 30 is a recess 30. The recess 30 includes an opening 30a configured to engage a corresponding protrusion 34 of the exterior support member 22, in use. A width of the opening 30a in the direction extending transverse to the pane of the glazing unit 18, in use, is less than a width of the remainder of the recess 30 in the same direction, thereby providing space in the recess 30 to locate the protrusion 34 whilst the opening 30a enables the retention of the protrusion 34, as will be described in more detail below. The recess 30 is substantially rectangular is cross-section, however any suitable shape of recess 30 may be used. The opening 30a is angled to act as a guide and direct the protrusion 34 of the exterior support member 22 into the recess 30, thus aiding the assembly process. The first engagement formation 32 is a male engagement formation 32 which corresponds to the female engagement formation 40 of the frame member 12d. The male engagement formation 32 is a protrusion 32 configured to be received in the first bead engagement formation 40, in use. In the embodiment shown in the Figures, the first engagement formation 32 is located on a leg 33 which extends from the interior support member 20 in a direction away from the internal volume 28. The first frame engagement formation 32 is located at a distal end of the leg 33 (i.e. the end which is remote form the internal volume 28). It shall be appreciated that in some embodiments, the leg 33 may be omitted or the first frame engagement formation 32 may extend from any suitable location on the leg 33. The protrusion 32 extends in a first direction and in an opposing second direction. In embodiments where the leg 33 is included, the protrusion 32 extends from the leg 33 in the first direction and in the opposing second direction. The first direction extends towards the first bead engagement formation 32, in use, and the second direction extends away from the first bead engagement formation 32, in use. The protrusion 32 extends equidistant in the first and second directions, however in alternative embodiments the protrusion 32 may extend different distances in the first and second directions. The leg 33 extends from one of the plurality of walls 26a-d of the interior support member 22. In particular, in the embodiment shown in Figures 3A and 3B, the leg 33 extends from the lowermost wall 26d of the plurality of walls 26a-d. The leg 33 is substantially linear, i.e. extends from the interior support member 22 in a direction parallel to a pane of the glazing unit 18 and includes a substantially constant cross-sectional shape. In alternative embodiments, any suitable shape of leg 33 may be provided. The protrusion 32 defines a first end 32a and an opposing second end 32b. As illustrated in Figures 3A and 3B, the protrusion 32 extends transversely from the leg 33 in the first and second directions. When the glazing bead assembly 14 is in the first configuration of Figure 3A and 3B, the first end 32a is the most remote end from the leg 33 in the first direction, and the second end 32b is the most remote end from the leg 33 in the second direction. The protrusion 32 is substantially linear, i.e. extends in a direction parallel to a transverse axis with respect to the pane of the glazing unit 18. The second end 32a extends beyond the first sidewall 26a. The protrusion 32 is offset from the central longitudinal axis a-a. Put another way, the protrusion 32 is located closer to the first sidewall 26a than to the second sidewall 26b. In embodiments where the leg 33 is included, the leg 33 from which the protrusion 32 extends is offset from the central longitudinal axis a-a. The exterior support member 22 includes the second support engagement formation 34 and a second frame engagement formation 36a, 36b. As discussed above, in the embodiment shown in the Figures, the second support engagement formation 34 is a male engagement formation 34. In particular, the second support engagement formation 34 is a protrusion 34 is located on the exterior support member 22 which engages the recess 30 of the interior support member 20. It shall be appreciated that in alternative embodiments, the protrusion may be located on the interior support member and the recess may be located on the exterior support member. It shall be appreciated that more than one recess and / or protrusion may be provided. Furthermore, alternative formations to recesses and protrusions may be provided. The exterior support member 22 includes the exterior surface 22a of the glazing bead assembly 14 and an interior surface 22b. The exterior surface 22a is visible from a location outside of the fenestration unit 10 and the interior surface 22b is located between the interior support member 20 and the exterior surface 22a. The exterior support member 22 abuts against the gasket 24. This helps to improve sealing of the glazing bead assembly 14. In the embodiment shown in Figures 3A and 3B, the exterior support member 22 is substantially L-shaped. Both the interior and exterior surfaces 22a, 22b of the exterior support member 22 are substantially L-shaped. As such, when viewed from the internal side of the fenestration unit 10, the glazing bead assembly 14 forms a substantially right-angled ledge. It shall be appreciated that in alternative embodiments, an alternative shape of exterior support member 22 may be used with a substantially right-angled exterior surface 22a. A shape of the interior and exterior surfaces 22a, 22b may differ. By way of example, the exterior support member 22 may have a substantially right-angled cross-sectional shape or rectangular cross-sectional shape. It shall be appreciated that in alternative embodiments, the exterior surface 22a of the exterior support member 22 may be any suitable shape, for example planar, curved or any alternative shape or combination thereof. The glazing bead assembly 14 defines a height configured to extend parallel to the pane of the glazing unit 18, in use. A height of the protrusion 34 located in the recess 30 is less than two thirds the height of the glazing bead assembly 14. In the embodiment shown in Figure 3A, the height of the protrusion is less than half the height of the glazing bead assembly 14. Providing a height of protrusion 34 which is less than the height of the glazing bead assembly 14 helps to increase overall flexibility of the glazing bead assembly 14 whilst reducing the amount of material used. Additionally, the thermal performance of the glazing bead assembly 14 is improved by providing an air gap or chamber. In alternative embodiments, the height of the protrusion 34 may be more than half that of the glazing bead assembly 14. It shall be appreciated that an entirety of the arrangement of the exterior support member 22 for fastening to the interior support member 20 (i.e. the portion of the exterior support member 22 which engages the interior support member 20) may be less than two thirds, for example less than half, the height of the glazing bead assembly 14. Put another way, the engagement between the interior support member 20 and the exterior support member 22 does not occupy more than half, more example more than one third, the height h of the glazing bead assembly 14. By way of example, in embodiments where more than one protrusion is provided, the height of each protrusion may be less than half, for example less than two thirds, the height of the glazing bead assembly 14. The protrusion 34 includes a tongue 34a. The tongue 34a is mounted to the recess 30 using a push-fit arrangement. The tongue 34a defines a leading end 35a and a trailing end 35b with respect to a direction of insertion T of the tongue 34a into the recess 30. A width of the tongue 34a decreases from the trailing end 35b towards the leading end 35a. In particular, the tongue 34a tapers from the trailing end 35b towards the leading end 35a. The decrease in the width of the tongue 34a creates a wedging effect on the opening 30a as the tongue 34a is inserted into the recess 30, thereby improving ease of insertion and removal of the tongue 34a into and from the recess 30. The tapered tongue 34a corresponds to the angled opening 30a, therefore helping to guide the tongue 34a into the recess 30. The protrusion 34 includes a neck portion 34b extending between the interior surface 22b of the exterior support member 22 and the tongue 34a. In particular, the neck portion 34b extends between the interior surface 22a of the exterior support member 22 and the trailing end 35b of the tongue 34a. A width of the neck portion 34b is less than the width of the trailing end 35b of the tongue 34a. The opening 30a of the recess 30 engages the neck portion 34b to retain the tongue 34a within the recess 30. The width of the opening 30a is less than a width of the trailing end 35b such that once the tongue 34a has been push-fitted into the recess 30, the opening 30a prevents the trailing end 35b from moving past the opening 30a and out of the recess 30. In the embodiment shown in Figures 3A and 3B, the leading end 35a of the tongue 34a is substantially curved. This, along with the increasing width of the tongue 34a from the leading end 35a to the trailing end 35b, enables smooth insertion of the tongue 34a through the opening 30a and into the recess 30. As described above, in the embodiment of Figures 3A and 3B, the interior support member 20 is formed from a material of greater flexibility than the exterior support member 22. As such, when the tongue 34a is push-fitted through the opening 30a and into the recess 30, it is the interior support member 20 which deforms as the tongue 34a engages the recess 30. Put another way, as the tongue 34a is inserted into the recess 30, the recess 30 flexes and a width of the opening 30a increases to accommodate the tongue 34a passing therethough. Once the tongue 34a has passed through the opening 30a, the recess 30 returns to a relaxed state thereof and the opening 30 located around the neck portion 34b. It shall be appreciated that in alternative embodiments where the tongue 34a is formed from a material of greater flexibility than the recess 30, the recess 30 may deform as the tongue 34a engages the recess 30. It shall be appreciated that in alternative embodiments, a snap-fit arrangement may be used to mechanically fasten the interior support member 20 to the exterior support member 22. The second frame engagement formation 36a, 36b includes a foot 36a and a notch or recess 36b. The foot 36a extends from the exterior support member 22 in a direction away from the exterior surface 22a. The foot 36a is used to guide the exterior support member into engagement with the second bead engagement formation 42 during assembly of the fenestration unit 10. The notch 36b corresponds to and engages the wall 42 when the glazing bead assembly 14 is assembled to the frame member 12d. In particular, the notch 36b engages the distal end of the wall 42. The interior support member 20 is attachable to the exterior support member 22 in a first orientation corresponding to the first configuration of the glazing bead assembly 14, illustrated in Figures 2A, 3A and 3B and a second orientation corresponding to the second configuration of the glazing bead assembly 14, illustrated in Figures 2B and 4 such that the glazing bead assembly 14 is reversibly mountable to the first engagement formation 40 of the frame member 12d. In the first orientation, the first end 32a of the protrusion 32 is a leading end 32a with respect to a direction of inserted I of the protrusion 32 into the first bead engagement formation 40. In a second orientation, the second end 32b of the protrusion 32 is a leading end with respect to the direction of insertion I of the protrusion into the first bead engagement formation 40. In the second orientation, the interior support member 22 is orientated approximately 180° with respect to the first orientation. In the first orientation, a maximum width di between the first end 32a of the protrusion 32 and the second engagement formation 36a, 36b of the exterior support member 22 is the same as a maximum width d2 between the second end 32b of the protrusion 32 and the second engagement formation 36a, 36b of the exterior support member 22 in the second orientation. Put another way, the first frame engagement formation 32 and the second frame engagement formation 36a, 36b are of the same configuration in the first orientation and in the second orientation of the interior support member 20. The widths di, d? correspond to the widths wi, w2 of the frame members 12d, 112d. As such, this enables the glazing bead assembly 14 to be mounted to the first and second bead engagement formations 40, 42 of the frame members 12d, 112d in both the first and second orientation of the interior support member 20. In the embodiment of Figure 3A, in order for di and d2 to be substantially the same width, a difference between the maximum width between the protrusion 34 of the exterior support member 22 and the exterior surface 22a in the first orientation and the width between the protrusion 34 of the exterior support member 22 and the exterior surface 22a in the second orientation is twice a distance between the central axis a-a of the interior support member 20 and a parallel central axis of the protrusion 32. Put another way, when the glazing bead assembly 14 is in both the first configuration of Figure 3A and the second configuration of Figure 3B, an interface to the frame member 12d, 112d (i.e. the interface between the first and second frame engagement formations 32, 36a, 36b and the first and second bead engagement formations 40, 42) is the same. As such, glazing bead assemblies 14 of differing widths, i.e. the glazing bead assembly 14 in the configuration of Figure 3A and the glazing bead assembly 14 in the configuration of Figure 4, can both be used with the same arrangement of bead engagement formations 40, 42, and only the width of the exterior support member 22 is changed to accommodate the desired differing widths of frame member 12d, 112d in Figures 2A and 2B. It shall be appreciated that in alternative embodiments with different geometries, alternative distances may need to be altered for the widths di and dz to be approximately the same. By way of example, in order to modify the widths di, dz, a distance between the central axis a-a and the centre of the protrusion 32 (or of the leg 33) may be modified. Furthermore, it shall be appreciated that in order to provide the distances di, dz, the leg 33 may be located on the central axis a-a and the protrusion 32 may extend by differing amounts in the first and second directions. It shall be appreciated that in alternative embodiments where the widths wi, w2 of the frame members 12d, 112d differ, the above distances may be modified such that the distances di, dz are different in the first and second orientations. In the first orientation, a maximum width ds between one of the plurality of walls 26a-d of the interior support member 20 and the exterior surface 22a of the exterior support member 22 is greater than a maximum width d4 between one of the plurality of walls 26a-d of the interior support member 20 and the exterior surface 22a of the exterior support member 22 in the second orientation. In particular, it is the width between the second side wall 26b and the exterior surface 22a which is the maximum width in the first orientation, and the width between the first side wall 26a and the exterior surface 22a which is the maximum width in the second orientation. The widths ds, d4 correspond to the widths w3, w4 of the frame members 12d, 112d. As such, the widths d3, d4 may be modified for use with different frame members 12d, 112d of differing widths w3, w4. It shall be appreciated that in the embodiment of Figures 3A, 3B and 4, the widths d3, d4 are also equal to a maximum width of the exterior support member 22 because a free end of the exterior support member 22 is aligned with the respect sidewall 26a, 26b of the interior support member 22 in the height direction, in use. It shall be appreciated that the interior support member of Figure 3A (in the first orientation) is of the same configuration as the interior support member 20 of Figure 4 (in the second orientation). As described above, the arrangement of the first and second frame engagement formations 32, 36a, 36b and distances therebetween is also the same in the first orientation of Figure 3A and the second orientation of Figure 4. Accordingly, it is only the width of the exterior support member 22, as opposed to the interior support member 22 or bead engagement formations 40, 140, 42, 142 of the frame 12d, 112d, which needs to be modified for the glazing bead assembly 14 to be used with the different frame members 12d, 112d of Figure 2A and 2B. In particular, a maximum width of the exterior support member 22 may be modified and the distance between the protrusion 34 and the exterior surface 22a may be modified. In Figures 3A and 3B, the maximum width of the exterior support member 22 is greater than the maximum width of the exterior support member 22 in the configuration of Figure 4. It shall be appreciated that the maximum width of the exterior support member 22 may be modified to accommodate any suitable width w3, w4 of frame member 12d, 112d. It shall be appreciated that the reversible orientation of the interior support member 20 with respect to the exterior support member 22 may be included in embodiments where the enclosed internal volume 28 is omitted, and vice versa. A method of assembling a glazing unit 18, frame member 12d and glazing bead assembly 14 will be described hereafter with reference to Figure 5. In order to assemble the glazing bead assembly 14, the interior support member 20 is push-fitted to the exterior support member 22, as described above. To fit the glazing bead assembly 14 within the fenestration unit 10, the glazing unit 18 is first offered up to the frame 12 to seat against the opposing gasket 25 retained within the frame member 12d. The glazing bead assembly 14 is then fitted by insertion of the first engagement formation 32 into the first bead engagement formation 40 of the frame member 12d. In particular, the first end 32a of the protrusion 32 (i.e. the leading end 32a) is inserted into the first bead engagement formation 40. As illustrated in Figure 5, the first end 32a is inserted into the bead engagement formation 40 such that the protrusion 32 is angled with respect to the first bead engagement formation 40. It shall be appreciated that in embodiments where the interior support member 20 is mounted to the exterior support member 22 in the second orientation of Figure 4, the second end 32b of the protrusion 32 is the leading end during the method of assembly. When the first end 32a is inserted into the bead engagement formation 40, the second frame engagement formation 36a, 36b is brought into abutment with the frame member 12d. In particular, the foot 36a abuts against an uppermost surface of the wall 42 of the frame member 12d. The glazing bead assembly 14 is rotated in a direction RI. The direction RI is clockwise in Figure 5, however if the glazing bead assembly 14 was located on the opposing side of the glazing unit 18 then the direction RI would be anti-clockwise. Moving the glazing bead assembly 14 in the direction RI moves the protrusion 32 further into the first bead engagement formation 40 until the protrusion 32 and the first bead engagement formation 40 are approximately aligned. At the same time, the foot 36a moves over an uppermost surface of the wall 42 in a direction towards the distal end thereof, and past the distal end of the wall 42 so that the notch 36b engages the wall 42, in particular the distal end of the wall 42. The location of the protrusion 32 in the first bead engagement formation 40 prevents the glazing bead assembly 14 from being disassembled in the direction parallel to the pane of the glazing unit 18. Figures 6 and 7 illustrate an alternative embodiment of the glazing bead assembly 214. Like parts with the embodiment of Figures 3A, 3B and 4 are labelled with the prefix "2". It is therefore submitted that all the teachings outlined above in relation to Figures 2A to 5 are also applicable to Figures 6 and 7. The differences will be described hereafter. The first engagement formation 232 functions differently to that of Figures 3A, 3B and 4. The first engagement formation 232 is a protrusion 232, and also extends in the first and second directions to define first and second ends 232a, 232b. The first and second ends 232a, 323b are angled. In particular, the first and second ends 232a, 232b taper towards each other in a direction away from the enclosed internal volume 228. The channel 40 of the frame member 12d includes a complimentary angled surface, illustrated in Figure 8, which engages the first or second end 232a, 232b of the protrusion 232 as the glazing bead assembly 14 is assembled to the frame member 12d. As such, the complementary angled surfaces of the channel 40 and the first and second ends 232a, 232b guide the first engagement formation 232 into the channel 40. Furthermore, the second engagement formation 236 of the exterior support member 222 functions differently to the foot 36a and notch 36b. In the embodiment of Figures 6 and 7, the foot 36a is omitted and the second engagement formation 236 is a notch 236. The notch 236 engages the wall 42 in substantially the same way as the notch 36b. The foot 36a is not used in the embodiment of Figures 6 and 7 because the angled first or second end 232a, 232b performs the function of abutting against the frame member 12d, 112d as the glazing bead assembly 214 is fitted to the fenestration unit 10. A method of assembling a glazing unit 18, frame member 12d and glazing bead assembly 214 will be described hereafter with reference to Figure 8. The interior support member 220 is fastened to the exterior support member 222 in substantially the same way as described above in relation to Figure 5, and the glazing unit 18 is offered up to the fenestration unit 10. The glazing bead assembly 14 is fitted by locating the wall 42 of the frame member 12d in the notch 236 and abutting the first end 232a of the protrusion 232 against the angled surface of the channel 40. As illustrated in Figure 8, the glazing bead assembly 214 is rotated in a direction R2. The direction R2 is anti-clockwise in Figure 8, 5 however if the glazing bead 214 was located on the opposing side of the glazing unit 18, the direction R2 would be clockwise. Moving the glazing bead assembly 214 in the direction R2 causes the first end 232a to be guided over the angled surface of the channel 40 and into the channel 40 where it relaxes into a snap fit engagement. Although the teachings have been described above with reference to one or more preferred 10 embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope as defined in the appended claims. For example the interior support member 20, 220 may be manufactured with a gasket 24, 224 on both walls 26a, 226a, 26b, 226b so it may be used in both orientations when supplied to an installer, further reducing the number of distinct parts required. 15

Claims

1. A glazing bead assembly for retaining a glazing unit within a frame member, the glazing bead assembly comprising:an elongate bead body comprising an interior support member formed from a first material and an exterior support member formed from a second material different from the first material;wherein the interior support member comprises a plurality of walls defining an enclosed internal volume therebetween extending along an elongate length thereof;wherein the interior support member comprises a recess or protrusion located on one of the plurality of walls of the interior support member, wherein the recess or protrusion is configured to engage the other of a recess or protrusion located on an interior surface of the exterior support member so as to mechanically fasten the interior support member to the exterior support member to form the bead body;wherein the interior support member and the exterior support member each comprise a respective first or second frame engagement formation configured to engage a respective first or second complementary bead engagement formation of the frame member, in use.

2. The glazing bead assembly according to claim 1, wherein the protrusion of the exterior support member or the interior support member comprises a tongue, and wherein the tongue is mounted to the recess using a push-fit arrangement.

3. The glazing bead assembly according to claim 2, wherein the tongue defines a leading end and a trailing end with respect to a direction of insertion of the tongue into the recess, and wherein a width of the tongue decreases from the trailing end to the leading end.

4. The glazing bead assembly according to claim 2 or claim 3, wherein the protrusion comprises a neck portion extending between the interior surface of the exterior support member and the tongue, and wherein an opening of the recess engages the neck portion to retain the tongue within the recess, in use.

5. The glazing bead assembly according to any preceding claim, wherein the glazing bead assembly defines a height configured to extend parallel to a pane of the glazing unit, in use, and wherein a length of the protrusion located in the recess isless than two thirds of the height of the glazing bead assembly, optionally less than half the height of the glazing bead assembly.

6. The glazing bead assembly according to any preceding claim, wherein the first frame engagement formation is a protrusion, and wherein the protrusion is configured to be received in the first bead engagement formation of the frame member, in use, optionally wherein the protrusion extends in a first direction configured to extend towards the first bead engagement formation, in use, and in an opposing second direction configured to extend away from the first bead engagement formation, in use.

7. The glazing bead assembly according to claim 6, wherein the interior support member comprises a leg extending therefrom in a direction away from the internal volume, and wherein the protrusion is located on the leg, optionally at a distal end of the leg.

8. The glazing bead assembly according to any preceding claim, wherein the interior support member is attachable to the exterior support member in a first orientation and in a second orientation such that the glazing bead assembly is configured to be reversibly mountable to the first engagement formation of the frame member, in use.

9. The glazing bead assembly according to claim 8 when dependent on claim 6, wherein the protrusion defines a first end and an opposing second end, and wherein in the first orientation the first end of the protrusion is a leading end with respect to a direction of insertion of the protrusion into the first bead engagement formation of the frame member and in the second orientation the second end of the protrusion is the leading end with respect to the direction of insertion of the protrusion into the first bead engagement formation of the frame member.10.The glazing bead assembly according to claim 9, wherein in the first orientation, a maximum width between one of the plurality of side walls of the interior support member and an exterior surface of the exterior support member is greater than a maximum width between one of the plurality of sidewalls and the exterior surface of the exterior support member in the second orientation.

11. The glazing bead assembly according to any one of claim 8 to claim 10, wherein in the second orientation, the interior support member is orientated approximately 180° with respect to the first orientation.12.The glazing bead assembly according to any preceding claim, wherein the recess is located on the interior support member and the protrusion is located on the exterior support member.13.The glazing bead assembly according to claim 12, wherein the recess is located on one of the plurality of walls and extends into the internal volume, and wherein the plurality of walls enclose the internal volume to define a substantially U-shaped cross-sectional shape of the internal volume.14.The glazing bead assembly according to any preceding claim, wherein the plurality of walls of the interior support member comprise opposing sidewalls extending between an uppermost and a lowermost wall, optionally wherein the opposing sidewalls are substantially parallel.15.The glazing bead assembly according to any preceding claim, wherein the recess or protrusion and the first frame engagement formation are located on opposing walls of the plurality of walls of the interior support member such that the internal volume is located between the recess or protrusion and the first frame engagement formation.16.The glazing bead assembly according to claim 15 when dependent on claim 14, wherein the recess or protrusion is located on the uppermost wall of the interior support member and wherein the first frame engagement formation is located on the lowermost wall of the interior support member and extends in a direction away from the internal volume.17.The glazing bead assembly according to any preceding claim, wherein the internal volume occupies a majority of a total cross-sectional area of the interior support member.18.The glazing bead assembly according to any preceding claim, wherein at least one gasket is mounted to the interior support member, optionally wherein the gasket is a bubble gasket.19.The glazing bead assembly according to claim 18, wherein the at least one gasket is coextruded with the interior support member.20.The glazing bead assembly according to any preceding claim, wherein the coextruded gasket is formed using a thermoplastic elastomer (TPE).21.The glazing bead assembly according to any preceding claim, wherein the interior support member is formed from a material of greater flexibility to the exterior support member.22.The glazing bead assembly according to claim 21, wherein the interior support member is formed form uPVC.23.The glazing bead assembly according to claim 21 or claim 22, wherein the exterior support member is formed from an aluminium alloy.

24. A fenestration unit for installation within an opening, the fenestration unit comprising:at least one frame member comprising first and second bead engagement formations;a glazing bead assembly according to any preceding claim fastened to the bead engagement formations of the frame member so as to define a groove therebetween;a glazing unit positioned within a portion thereof the groove and retained in the groove by the glazing bead assembly.

25. A glazing bead assembly for retaining a glazing unit within a frame member, the glazing bead assembly comprising:an elongate bead body comprising an interior support member formed from a first material and an exterior support member formed from a second material different from the first material;wherein the interior support member comprises a first support engagement formation configured to engage a complementary second support engagement formation located on an interior surface of the exterior support member so as to mechanically fasten the interior support member to the exterior support member to form the bead body;wherein the interior support member and the exterior support member each comprise a respective first or second frame engagement formation configured toengage a respective first or second complementary bead engagement formation of the frame member, in use; andwherein the interior support member is attachable to the exterior support member in a first orientation and in a second orientation such that the glazing bead5 assembly is configured to be reversibly mountable to the first bead engagementformation of the frame member, in use.30

Images