A sealed mitre joint and associated method of manufacture

Abstract

A sealed mitre joint is disclosed. It has first 120a and second 120b frame members with hollow end portions, and a corner piece 200 with first and second legs to be fitted into the ends of the frame m

Description

FIELD OF THE INVENTION

[0001] The present disclosure relates to a sealed mitre joint, as well as to an associated method of manufacture. More particularly, though not exclusively, the disclosure relates to sealing the mitre joints of a glazing unit frame assembly or of a roof assembly. BACKGROUND

[0002] Where a frame, such as a glazing unit frame or a roof assembly, is constructed from extruded edge frame members, it is known to form mitre joints between those edge frame members through use of a corner piece, also known as a corner key, which has first and second leg portions respectively received in open portions of adjacent ends of the edge frame members.

[0003] It is known to mechanically secure the adjacent frame members to the corner piece, for example by use of screws or by punching tab portions of the frame members into recesses in the corner piece. Once the frame members have been mechanically fixed in position, defining a mitre joint line, adhesive may be injected into the area to further fix the assembly and to improve the sealing. EP0610674A1 discloses one such example. However, injection of the adhesive into the joint may be difficult because it must flow into a narrow lateral gap defined between the interior of upper faces of the respective edge members and the upper face of the corner piece, and likewise into a narrow lateral gap defined between the interior of lower faces of the respective edge members and the lower face of the corner piece. Accordingly, the application of the adhesive into those narrow gaps requires a combination of high pressure and low viscosity. Moreover, the adhesive bonds the frame members together, via the corner piece, under shear. It is also difficult to determine whether sufficient adhesive has been applied.

[0004] In known roof assemblies, such as fixed pitch roof assemblies, a glazed roofing system having glazed panels and rafters is assembled so as to provide a roof having a fixed pitch. Alternatively, the lantern roof may include polycarbonate panels in place of glazing. In some examples, a fixed pitch roof has a ridge and rafters extending at a fixed pitch and angle from a boss, which itself is connected to the ridge. In some examples, a pyramid-style lantern roof has no ridge, and may include a plurality of rafters meeting at a single lantern boss. At their opposing ends from the lantern boss, the rafters are secured to frame members, such as at a mitre joint defined between eaves beams fixed to a wall.

[0005] Known mitre joints thereby provides a complex junction between surfaces of frame members, rafters and panels, each of which require an effective seal to prevent unwanted ingress of moisture. Certain mitre joints for roof assemblies may include a corner piece to aid assembly of the frame members and / or rafters. However, these corner pieces further increase the complexity of the junction because there provide additional surfaces that require sealing in order to make the joint water-tight. SUMMARY OF THE INVENTION

[0006] The invention is set out in the appended claims.

[0007] According to an aspect of the invention, there is provided a sealed mitre joint including: a first frame member, having a first hollow core portion open towards a first end thereof, a second frame member, having a second hollow core portion open towards a second end thereof, a corner piece having a respective first leg portion and a respective second leg portion received in the corresponding first end and second end of the associated frame members, a rafter releasably secured to the first frame member and the second frame member, a mechanical fastening to secure the first frame member and the second frame member to the corner piece with the respective first end and second end thereof in abutment forming a joint line, where the first frame member, second frame member and the corner piece together define a first closed channel along a portion of the joint line, and an injection port into the first closed channel, where solidifying liquid sealant injected into the injection port fills the first closed channel, forming a sealing bead.

[0008] In this way, a sealed mitre joint is provided for a roof assembly that can be easily sealed by the installer. The rafter is secured with the mitre joint while providing a convenient means for sealing at least a portion of the joint line between the frame members.

[0009] According to another aspect, there is provided a sealed mitre joint including: a first frame member with a hollow core portion open towards a first end thereof; a second frame member with a hollow core portion open towards a second end thereof; a corner piece with respective first and second leg portions received in the corresponding first and second ends of the associated frame members; a mechanical fastening to secure the first and second frame members to the corner piece with the respective first and second ends thereof in abutment forming a joint line, wherein the first and second frame members and the corner piece together define a closed channel circumscribing the joint line; and an injection port into the closed channel, whereby solidifying liquid sealant injected into the injection port fills the channel, forming a sealing bead.

[0010] Advantageously, the arrangement allows for a well-defined sealing bead to be applied easily and quickly, and specifically at the joint line. Due to the closed loop form of the channel, the sealing bead within acts only under tension to bond the opposed faces of the respective frame members to one another in abutment. The mechanical strength of the joint is provided by the mechanical fastening, whereas the solidified liquid sealant is not required to add any structural strength; rather, is there merely to seal the joint line.

[0011] The sealed mitre joint may be a roof assembly sealed mitre joint. The associated roof assembly may include a suitable arrangement of glazed panels and associated gaskets, as known in the art. The roof assembly may be a fixed pitch roof assembly of, for example, a roof lantern.

[0012] The corner piece may include a first bore. The first bore provides fluid communication through the corner piece, from the injection port to the first closed channel. In this way, the solidifying liquid sealant may be easily directed from an outer wall of the mitre joint frame member to a closed channel that would otherwise be remote from the injection port. The corner piece may include a plurality of first bores.

[0013] The corner piece may include an engaging surface. The engaging surface is for contactingly receiving a proximal end portion of the rafter when the rafter is secured within the mitre joint. In certain examples, the engaging surface may include a guide means configured to align a proximal end portion of the rafter within the mitre joint.

[0014] In these ways, the rafter may be easily located with the frame members of the mitre joint. The corner piece coordinates the relative locations of the frame members as well as the rafter within the mitre joint so that the frame members are aligned correctly relative to the rest of the roof assembly, for example the fixed pitch boss and optional ridge, secured to the distal end of the mitre joint rafter.

[0015] The sealed mitre joint may also be configured so that, with the rafter secured to the first frame member and second frame member, a rafter proximal end portion is in abutment with the engaging surface of the corner piece. By the providing an abutment of the engaging surface with the corner piece, the proximal end portion and the engaging surface together define a second closed channel in fluid communication with the injection port. In this way, the rafter is conveniently and easily sealed within the sealed mitre joint.

[0016] The closed channel may include a groove formed in the corner piece, or may include opposed recesses in each of the first and second frame members, or a combination of the two. By way of example, the corner piece may include a moulded thermoplastic item, and the closed channel may be defined, or partly defined, by a groove formed during the moulding process.

[0017] The closed channel may have a cross sectional area in the range of 7 to 80 mm2. This corresponds to a bead having a diameter in the range of approximately 3 to 10 mm, as is typical for conventional liquid construction sealant.

[0018] The liquid sealant is typically silicone based. Such sealants typically have a flow viscosity in the range of about 50000 to 150000 milli-Pascal seconds (mPa.s) at ambient temperature. In one particular embodiment, for a liquid sealant, which may be silicone-based, having a viscosity of about 130000 mPa.s at ambient temperature, a diameter of the flow channel is selected to be about 5 millimetres (or the equivalent cross-sectional area of about 20 millimetres squared).

[0019] The injection port may be defined on the joint line, across the first and second frame members. For example, the injection port may include a circular hole, with a semi-circular hole in the first frame member in registration with a corresponding opposed semi-circular hole in the second frame member. This provides a convenient site to ensure that the sealant bead is applied exactly where needed, symmetrically on the joint line.

[0020] The sealed mitre joint may include a vent port. The vent port may provide fluid communication out of one or more of the closed channels. The vent port may be substantially opposite to the injection port, or the vent port may be adjacent to the injection port. As with the injection port, the vent port may be defined on the joint line, across the first and second frame members. The provision of a vent port not only helps to displace air within the channel, thereby assuring that the bead of liquid sealant may be applied easily and at low pressure, but also provides a convenient mechanism for visual proof that the channel has been filled; when the sealant is seen to exit the vent port injection may be stopped.

[0021] The corner piece may include a second bore. The second bore provides fluid communication from a first closed channel to a second closed channel. Thus, the second bore enables the installer to fill both the first closed channel and the second closed channel with a single injection of the solidifying liquid sealant into the injection port. The corner piece may include a plurality of second bores.

[0022] The corner piece may also include a third bore configured to provide fluid communication through the corner piece to the vent port. The third bore may provide fluid communication from any exterior face of the corner piece to the vent port. In certain examples, the third bore extends from an upper face, a lower face, or an elongate recess providing fluid communication from the upper face to the lower face of the corner piece. In certain examples, the third bore extends from a first closed channel, or a second closed channel in the corner piece. In certain examples, the third bore extends from a first bore, or a second bore in the corner piece. The corner piece may include a plurality of third bores.

[0023] The first bore, second bore, third bore, and elongate recesses together define multiple possible pathways for fluid communication for the flow of solidifying liquid sealant around the mitre joint. As will be appreciated other variations of pathways may be possible by incorporating different combinations, or different numbers, of each of the bores and elongate recesses. Pathways may be possible without including one or more of a first bore, a second bore, a third bore, or an elongate recess.

[0024] The first frame member may include a first receiving slot portion and the second frame member may include a second receiving slot portion. The first receiving slot portion and the second receiving slot portion may be cut-out regions on an interior wall of the associated frame member. The first receiving slot portion and second receiving slot portion together form a rafter receiving slot to mount the rafter in the mitre joint. In this way, the receiving slot portions provide a convenient way of the locating a rafter within the sealed mitre joint.

[0025] The sealed mitre joint may include a fluid pathway through the corner piece from the injection port to at least one of: the first hollow core portion or the second hollow core portion.

[0026] The corner piece may include an upper face having a drainage means. The drainage means may include one or more channel, trough, or depression in the upper face. The drainage means may include an outlet. The outlet may extend in the direction of an intersection axis from an outer intersection of the first leg portion and the second leg portion. The channel, trough or depression may be provided on the upper face of the corner piece in fluid communication with the outlet. In this way, the drainage means is configured to collect unwanted fluid that may collect in the mitre joint, such as water condensation within a first frame member, a second frame member or a rafter. Fluid collected by the drainage means flows under gravity to the outlet, and is then directed out of the mitre joint.

[0027] In some embodiments, the corner piece may be a unitary member including both the first and second leg portions. As noted above, this may be formed of a moulded thermoplastic. In such embodiments, the mechanical fastening may include a first fastener, such as a screw, passing through the first frame member into the first leg of the corner piece, and a second fastener, such as another screw, passing through the second frame member into the second leg of the corner piece. By virtue of the unitary nature of the corner piece, by securing the respective frame members to the associated leg portions, those frame members are necessarily secured to one another.

[0028] In alternative embodiments, the corner piece includes separate first and second parts, the first part including the first leg portion and the second part including the second leg portion, wherein the first and second parts are releasably secured together by a releasable fastening mechanism. In such embodiments, the releasable fastening mechanism may include: a first insert for insertion through an aperture in an exterior face of the first frame member and a corresponding aperture on an external face of the first leg portion, the first insert including a first pocket angled towards the second frame member; and a second insert for insertion through an aperture in an exterior face of the second frame member and a corresponding aperture on an external face of the second leg portion, the second insert including a second pocket angled towards and aligned with the first pocket; whereby respective parts of a threaded fastener coupling can be inserted in the respective first and second pockets, such that tightening the threaded fastener respectively urges the first and second parts of the corner piece towards secure engagement with one another.

[0029] In certain embodiments, one of the inserts may include a threaded aperture to form one part of the threaded fastener coupling, with a mating bolt inserted through the other insert forming the corresponding mating part of the threaded fastener coupling. Because the threaded fastener coupling securely engages the first and second parts of the corner piece to one another, and because the first and second inserts are retained within the respective apertures in the frame members, the threaded fastener coupling also securely engages the first and second frame members to the corner piece in the same action. Thus, the releasable fastening mechanism includes the mechanical fastening that secures the first and second frame members to the corner piece.

[0030] The joint of such embodiments may further include an intermediate plate sandwiched between the first and second parts of the corner piece, the plate including an aperture to receive and align respective distal ends of the first and second pockets. The intermediate plate may thus help to align the first and second parts of the corner piece and, by extension, the first and second frame members. In certain embodiments the groove defining the channel may be at least partially formed in the alignment plate.

[0031] The first and second frame members each may include an extrusion. As such, the frame members may each include an extruded aluminium profile or may include extruded profiles of insulating material, such as suitable thermoplastic materials, but it will be appreciated that other suitable materials may be used instead.

[0032] According to another aspect of the invention, there is provided a method of forming a sealed mitre joint, including: providing a first frame member with a hollow core portion open towards a first end thereof; providing a second frame member with a hollow core portion open towards a second end thereof; providing a corner piece having respective first and second leg portions; inserting the first leg portion into the first end of the first frame member and inserting the second leg portion into the second end of the second frame member such that the respective first and second ends thereof are in abutment forming a joint line, whereby the first and second frame members and the corner piece together define a closed channel circumscribing the joint line; securing the first and second frame members to the corner piece with a mechanical fastening; and injecting solidifying liquid sealant through an injection port into the closed channel thereby filling the channel and forming a sealing bead.

[0033] According to a yet further aspect of the invention, there is provided a method of forming a sealed mitre joint, including: providing a first frame member with a hollow core portion open towards a first end thereof; providing a second frame member with a hollow core portion open towards a second end thereof; providing a corner piece having respective first leg portion and second leg portion; releasably securing a rafter to the first frame member and the second frame member; inserting the first leg portion into the first end of the first frame member and inserting the second leg portion into the second end of the second frame member such that the respective first and second ends thereof are in abutment forming a joint line, whereby the first and second frame members and the corner piece together define a first closed channel along a portion of the joint line; securing the first and second frame members to the corner piece with a mechanical fastening; and injecting solidifying liquid sealant through an injection port into the closed channel thereby filling the channel and forming a sealing bead.

[0034] Advantageously, the methods allows a manufacturer of mitre joints, such as those in a frame assembly, to apply a well-defined sealing bead easily and quickly, and specifically at the joint line.

[0035] The channel may include a groove formed in the corner piece, or may include opposed recesses in each of the first and second frame members, or a combination of the two.

[0036] The channel may have a cross sectional area in the range of 7 to 80 mm2. As noted above, this may correspond to a channel diameter (or equivalent dimensions) of about 3 to 10 mm.

[0037] The injection port may be defined on the joint line, across the first and second frame members. For example, the injection port may include a circular hole, with a semi-circular hole in the first frame member in registration with a corresponding opposed semi-circular hole in the second frame member. This provides a convenient site to ensure that the sealant bead is applied exactly where needed, symmetrically on the joint line. In other embodiments, it can be envisaged that injection could also take place away from the sealing line, with internal channeling provided to allow flow onto and around the joint line.

[0038] Preferably, the joint further includes a vent port out of the closed channel. The vent port may be substantially opposite to the injection port. As with the injection port, the vent port may be defined on the joint line, across the first and second frame members. The provision of a vent port not only helps to displace air within the channel during injection, thereby assuring that the bead of solidifying liquid sealant may be applied easily and at low pressure, but also provides a convenient mechanism for visual proof that the channel has been filled; when the sealant is seen to exit the vent port injection may be stopped.

[0039] In some embodiments, the corner piece includes a unitary member including both the first and second leg portions. As noted above, this may be formed of a moulded thermoplastic. In such embodiments, the mechanical fastening may include first and second fasteners, and securing the first and second frame members to the corner piece may include passing the first fastener through the first frame member into the first leg of the corner piece, and passing the second fastener through the second frame member into the second leg of the corner piece. By virtue of the unitary nature of the corner piece, by securing the respective frame members to the associated leg portions, those frame members are necessarily secured to one another.

[0040] In alternative embodiments, the corner piece includes separate first and second parts, the first part including the first leg portion and the second part including the second leg portion, the method further including releasably securing the first and second parts together by a releasable fastening mechanism. In such embodiments, the releasable fastening mechanism may include: a first insert including a first pocket angled towards the second frame member; and a second insert including a second pocket angled towards and aligned with the first pocket; and the method may further include: inserting the first insert through an aperture in an exterior face of the first frame member and a corresponding aperture on an external face of the first leg portion; inserting the second insert through an aperture in an exterior face of the second frame member and a corresponding aperture on an external face of the second leg portion; inserting respective parts of a threaded fastener coupling in the respective first and second pockets; and tightening the threaded fastener coupling to urge the first and second parts of the corner piece into secure engagement with one another; wherein tightening the threaded fastener coupling also includes said step of securing the first and second frame members to the corner piece with a mechanical fastening.

[0041] The methods may further include sandwiching an intermediate plate between the first and second parts of the corner piece, including aligning respective distal ends of the first and second pockets in an aperture through the intermediate plate. The intermediate plate may thus help to align the first and second parts of the corner piece and, by extension, the first and second frame members. In certain embodiments the groove defining the channel may be at least partially formed in the alignment plate. In some embodiments, the intermediate plate may include first and second portions, for example symmetrically arranged about the joint line, wherein the first portion of the intermediate plate may be sealed to the first frame member and the second portion of the intermediate plate may be sealed to the second frame member in a preliminary stage of assembly, to be drawn into abutting alignment once the two parts of the corner piece are assembled together. Then, once the first and second frame members are abutted together over the assembled corner piece, an additional seal may be applied - via injection of a solidifying liquid sealant through the injection port into the channel, as above, where the channel is defined by a groove in one or both of the first and second portions of the intermediate plate. This may include over-moulding the sealing bead as formed in the channel over the respective seals between the first and second portions of the intermediate plate and the first and second frame members formed in the preliminary stage. In such embodiments, the joint may be at least partially disassembled without compromising the seals as formed between the respective first and second frame members and the associated first and second portions of the intermediate plate.

[0042] The first and second frame members may each include an extrusion. As such, the frame members may each include an extruded aluminium profile or may include extruded profiles of insulating material, such as suitable thermoplastic materials, but it will be appreciated that other suitable materials may be used instead.

[0043] The liquid sealant may include a solidifying silicone sealant. Injecting the solidifying liquid silicone sealant may include inserting the nozzle of a manual applicator tool into the injection port. Thus, the sealing bead may be formed using readily-available construction kit, such as a caulking gun, and under relatively low pressures. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0044] Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. In the drawings, like reference numbers are used to identify like or functionally similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. FIG. 1 shows a schematic diagram of a frame having mitred joints at the corners; one side frame member is omitted; FIG. 2 shows a cross-section through a frame member of the frame of FIG. 1; FIG. 3 shows a schematic mitre joint assembly, depicting first and second frame members being inserted on to an associated corner piece; FIG. 4 shows a horizontal cross-section through a mitre joint assembly such as that of FIG. 3; FIG. 5 shows an embodiment in which a channel is formed as a groove in the corner piece; FIG. 5 A is a cross-section through the corner piece of FIG. 5 on A-A; FIG. 6 shows an alternative embodiment, in which the channel is formed as opposed recesses in opposed ends of the first and second frame members; FIG. 6A and FIG. 6B are cross-sections through the joint of 6, on B-B and C-C respectively; FIG. 7 shows a schematic cross-section through an exemplary joint, taken along the engaging surface; FIG. 8 substantially corresponds to FIG. 7, but shows another part of the corner piece and an associated insert; FIG. 9 shows a detail view of a corner portion of a larger frame assembly, with parts omitted for clarity and depicting first and second inserts of a mitre joint according to embodiments and highlighting an intermediate plate; FIG. 10 shows a corresponding detail view highlighting an insert and associated threaded fastener coupling; FIG. 11 shows a horizontal cross-section through the corner portion; FIG. 12 shows a schematic diagram of roof assembly, including a sealed mitre joint; FIG. 13 shows a rear perspective view a sealed mitre joint such as used in the roof assembly shown in FIG. 12; FIG. 14A shows a first frame member of the sealed mitre joint of FIG. 13; FIG. 14B shows the first frame member of FIG. 14A with a corner piece mounted to the first frame member; FIG. 15A shows an upper perspective view of the corner piece of FIG. 14B; FIG. 15B shows a lower perspective view of the corner piece of FIG. 14B; FIG. 16 shows the sealing bead of FIG. 13 with the second frame member removed; FIG. 17 shows a cross-section, viewed from below, through the joint of FIG. 13 on D-D; and FIG. 18 shows an upper view of the joint of FIG. 13. DETAILED DESCRIPTION

[0045] In the following description, for purposes of explanation, numerous specific details of certain examples are set forth. Reference in the specification to “an example” or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in at least that example, but not necessarily in other examples.

[0046] Certain terminology is used in the following description for convenience only and is not limiting. The words Tower’, ‘upper’, ‘front’, ‘rear’, ‘upward’, ‘down’ and ‘downward’ designate directions in the drawings to which reference is made and are with respect to the described component when assembled and mounted. The words ‘inner’, ‘inwardly1 and ‘outer’, ‘outwardly’ refer to directions toward and away from, respectively, a designated centreline or a geometric centre of an element being described (e.g. central axis), the particular meaning being readily apparent from the context of the description.

[0047] Further, as used herein, the terms ‘connected1, ‘secured’, ‘mounted’ are intended to include direct connections between two members without any other members interposed therebetween, as well as, indirect connections between members in which one or more other members are interposed therebetween. The terminology includes the words specifically mentioned above, derivatives thereof, and words of similar import.

[0048] Further, unless otherwise specified, the use of ordinal adjectives, such as, ‘first’, ‘second’, ‘third’ etc. merely indicate that different instances of like objects are being referred to and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking or in any other manner.

[0049] FIG. 1 shows a schematic diagram of a frame 100 having a mitre joint 110 at the corners where adjacent edge frame members 120 meet. One edge frame member 120 is omitted to show ends 122 of two of the edge frame members 120, each cut at a ±45 degree angle relative to a longitudinal axis of each edge frame members 120 , thereby each forming a 90 degree, right-angled joint. The depicted frame 100 is a glazing unit frame assembly and the mitre joint 110 of the invention and its associated method of forming will be described in this context. However, it will be appreciated that the invention can be applied more broadly to any mitre joints where it might be beneficial to have a well-sealed joint, such as a roof assembly as described below.

[0050] FIG. 2 shows a vertical cross-section through an exemplary frame member 120, taken perpendicular to its longitudinal axis. The frame member 120 includes a hollow core 130.

[0051] FIG. 3 and FIG. 4 depict, in simplified form, a mitre joint 110 according to an embodiment of the invention. The mitre joint 110 comprises a first frame member 120a, a second frame member 120b and an associated corner piece 200. The corner piece 200 has first and second leg portions 202a, 202b extending at 90 degrees to one another. The first frame member 120a has a hollow core portion 130a open towards a first end 122a and is inserted (arrow A) onto the corner piece 200 such that the first leg portion 202a is received in the hollow core portion 130a. Correspondingly, the second frame member 120b has a hollow core portion 130b open towards a second end 122b and is inserted (arrow B) onto the corner piece 200 such that the second leg portion 202b is received in the hollow core portion 130b. The respective first and second ends 122a, 122b of the frame members 120a, 120b are brought into abutment over the corner piece 200, thus forming a joint line 300 which is coplanar with the first end 122a and the second end 122b.

[0052] As depicted, the 120a, 120b are extrusions, which may comprise an extruded aluminium profile or may comprise an extruded profile of insulating material, such as suitable thermoplastic materials. It will be appreciated that other suitable materials may be used instead. However, it will be understood that it is not necessary for the hollow core to extend through the whole longitudinal extent of the frame members; it would be sufficient for there to be a hollow portion at the end to receive the associated leg portion of the corner piece 200.

[0053] A mechanical fastening secures the first and second frame members 120a, 120b to the corner piece 200 with the respective first and second 122a, 122b thereof in abutting engagement. As depicted, the mechanical fastening is in the form of a first fastener, such as a screw, 140a passing through the first frame member 120a into the first leg portion 202a of the corner piece, and a second fastener, such as another screw, 140b, passing through the second frame member 120b into the second leg portion 202b of the corner piece. Where the corner piece 200 comprises a single, unitary part, this is sufficient to mechanically secure the first and second frame members 120a, 120b both to the corner piece 200 and to one another. In other embodiments, described later, the corner piece may comprise more than a single part.

[0054] The first and second frame members 120a, 120b and the corner piece 200 together define a closed channel 150 circumscribing the joint line 300. In some embodiments, for example as shown in FIG. 5 and 5A, the closed channel 150 comprises a groove 210 formed in the corner piece 200. In other embodiments, for example as depicted in FIG6, FIG. 6A and FIG. 6B, the closed channel 150 comprises opposed recesses 124a, 124b in each of the first and second frame members 120a, 120b. In yet other embodiments (not shown), the closed channel 150 may be formed as a combination of these aspects; one portion being defined by a groove in the corner piece 200 and another portion being formed as recesses in the respective first and second frame members 120a, 120b.

[0055] An injection port 180 is in fluid communication with the closed channel 150 from an exterior of the joint. In particular, the injection port 180 comprises a hole passing through an upper outer surface of one or both of the frame members 120a, 120b Preferably, the injection port 180 is defined on the joint line, across the first and second frame members 120a, 120b, such as taking the form of two mating, opposed semi-circular hole portions 180a, 180b.

[0056] The injection port 180 allows solidifying liquid sealant to be injected into the port so as to fill the closed channel 150 by flowing into and around it whilst in liquid form, subsequently to go off thereby solidifying and forming an encapsulating sealing bead about the whole interior periphery of the joint line 300.

[0057] A vent port 190 is preferably provided, in fluid communication with the closed channel 150, to allow air in the closed channel 150 to vent out as the solidifying liquid sealant is injected. In particular, the vent port 190 comprises a hole passing through a lower outer surface of one or both of the frame members. Preferably, the vent port 190 is defined on the joint line, across the first and second frame members 120a, 120b, such as taking the form of two mating, opposed semi-circular hole portions 190a, 190b, similar to the injection port 180. By locating the vent port 190 on an opposite side of the joint line 300 to the injection port 180, a user can be assured that when they see sealant flow out of the vent port 190 the entire closed channel 150 has been filled and the sealing bead has thus been fully formed.

[0058] Exemplary liquid sealants that may be used in the joint of the invention and the associated method may comprise a 1-part construction RTV silicone sealant, as typically used in the construction industry. Such sealants conventionally have a viscosity in the range of about 50000 to 150000 mPa.s, and most typically of about 130000 mPa.s, which is ideal for flow into the closed channel 150 having a diameter in the range of 3 to 10 mm, preferably about 5 mm (or equivalent non-circular dimensions for an equivalent cross-sectional area).

[0059] In some embodiments, as for example shown in the context of the wider frame assembly 100 and FIG. 7 to FIG. 11, the corner piece 200’ may comprise separate first and second parts; the first part 220 including the first leg portion 202a and the second part 222 including the second leg portion 202b. The first and second parts 220,222 are releasably secured together by a releasable fastening mechanism 240. The releasable fastening mechanism 240 comprises a first insert 260a for insertion through an aperture 262a in an exterior face of the first frame member 120a and a corresponding aperture (not shown) on an external face of the first leg portion 202a, the first insert 260a including a first pocket 261 angled towards the second frame member 120b. The releasable fastening mechanism 240 also comprises a second insert 260b for insertion through an aperture (not shown) in an exterior face of the second frame member 120b and a corresponding aperture (not shown) on an external face of the second leg portion 202b, the second insert 260b including a second pocket 263 angled towards and aligned with the first pocket 261. The releasable fastening mechanism 240 further comprises a threaded fastener coupling (not shown), whereby respective (male and female) parts of the threaded fastener coupling can be inserted in the respective first and second pockets 261,263, such that tightening the threaded fastener respectively urges the first and second parts 220,222 of the corner piece 200’ towards secure engagement with one another. Because the threaded fastener coupling securely engages the first and second parts 220,222 of the corner piece to one another, and because the first and second inserts 260a, 260b are retained within the respective apertures 262a,b in the frame members, the threaded fastener coupling also securely engages the first and second frame members 120a, 120b to the corner piece 200’ in the same action. Thus, the releasable fastening mechanism 240 also comprises the mechanical fastening that secures the first and second frame members to the corner piece. As such, there is no need for separate mechanical fastening means, such as the screws 140a,b of the embodiments depicted in FIG. 3 and FIG. 4, although such a mechanical fastening means could be included in addition.

[0060] Where the corner piece 200’ is formed of two parts 220, 222, the joint may further comprise an intermediate plate 400 sandwiched between the first and second parts 220, 222 of the corner piece. The intermediate plate 400 includes an aperture 402 to receive and align respective distal ends of the first and second 261, 263. The intermediate plate 400 may thus help to align the first and second parts 220, 222 of the corner piece and, by extension, the first and second frame members 120a, 120b. In certain embodiments the groove 210 defining the closed channel 150 may be at least partially formed in the intermediate plate 400.

[0061] Referring now to FIG. 12 there is shown a portion of a roof assembly 800 including a mitre joint according to certain embodiments described herein. The roof assembly 800 includes a first frame member 850a and a second frame member 850b forming a portion of the perimeter of the lowermost part of the roof assembly 800. In the example, the first frame member 850a is a first eaves beam and the second frame member 850b is second eaves beam. The first frame member 850a and a second frame member 850b are typically attached to a wall structure, for example to an upper surface or an exterior surface of a wall structure.

[0062] The roof assembly 800 comprises a ridge 810 forming the uppermost ridge of the roof assembly 800. The roof assembly 800 further comprises one or more rafters 820, 830, 840 such as a hip rafter 820. The rafters extend at a fixed pitch from an end of a ridge 810 to a mitre joint of the first frame member 850a and a second frame member 850b. The hip rafter 820 is attached to the first frame member 850a and the second frame member 850b at point B, as described in more detail with reference to the example shown in FIG. 13 to FIG. 18.

[0063] The roof assembly 800 may optionally comprise one or more support rafters 830, each support rafter 830 extending at a fixed pitch from the ridge 810 to the first frame member 850a. The support rafter 830 is attached to the first frame member 850a at point C. The support rafters 830 extend away from the ridge 810 in a longitudinal direction opposite the longitudinal direction of extension of the ridge 810 and at the same pitch as the hip rafters 820.

[0064] The roof assembly 800 may optionally comprise one or more centre rafters 840, the centre rafters 840 extending at a fixed pitch which is equivalent to the fixed pitch from which the hip rafter 820 and support rafter 830 descend from ridge 810. The central rafters 840 extend away from the ridge 810 in a longitudinal direction the same as the longitudinal direction of extension of the ridge 810 and at the same pitch as the hip rafters 820. The ridge 810 may be attached to one or more hip rafters 820 and optionally one or more central rafters 840 at point A. The central rafter 840 is attached to the second frame member 850a at point D.

[0065] The roof assembly 800 may optionally comprise one or more jack rafters 860, the one or more jack rafters 860 arranged to extend between a hip rafter 820 and the first frame member 850a or the second frame member 850b. In some examples, the jack rafters 860 may extend away from the hip rafter 820 in a direction substantially parallel with one or more support rafters 830 or one or more central rafters 840.

[0066] With the roof assembly 800 assembled, glazing units are installed into the various apertures defined by the frame members, rafters, and ridge components of the roof assembly. Suitable edge seals may be provided to seal the respective perimeters of the glazing units to the roof assembly.

[0067] Referring additionally to FIG. 13, there is shown a schematic of an example roof assembly connection at point B. The connection point B is a mitre joint 500 at the corner where adjacent first and second frame members 520a, 520b meet to engage a rafter 700, such as a hip rafter 820 of FIG. 12. The rafter 700 is an elongate beam of the roof assembly extending along a rafter axis.

[0068] The rafter 700 is arranged so that a proximal end portion 702 of the rafter 700 contacts a corner piece 600 secured within the mitre joint 500. The first frame member 520a is a first eaves beam. The second frame member 520b is a second eaves beam.

[0069] Each of the first frame member 520a and the second frame member 520b includes a respective end 522a, 522b, each cut at a ±45 degree angle relative to a longitudinal axis of each frame member 520a, 520b, thereby each forming a 90 degree, right-angled joint. The respective ends 522a, 522b form an abutment along a joint line. The joint line is aligned along a joint axis. The joint axis is oriented at a ±45 degree angle relative to a longitudinal axis of each frame member 520a, 520b.

[0070] The depicted mitre joint 500 is for a roof assembly mitre joint of the invention, and will be described in this context. However, it will be appreciated that the invention can be applied more broadly to any mitre joints where it might be beneficial to have a well-sealed joint that incorporates a third elongate component, such as a rafter.

[0071] Referring additionally to FIG. 14A and FIG. 14B, there are shown enlarged schematic diagrams of the first frame member 520a of the mitre joint 500, both with (FIG. 14A) and without (FIG. 14B) the corner piece 600.

[0072] Each of the first frame member 520a and the second frame member 520b is formed of two frame elements. The first frame member 520a includes an inner frame element 528a and a core frame element 529a. The inner frame element 528a and core frame element 529a together define a hollow core portion 530a for receiving an associated first leg portion 602a of the corner piece 600.

[0073] Likewise, the second frame member 520b includes a corresponding inner frame element 528b and core frame element 529b. The inner frame element 528b and core frame element 529b together define a hollow core portion 530b for receiving an associated second leg portion 602b of the corner piece 600.

[0074] As depicted, the frame elements are extrusions, which may comprise an extruded aluminium profile or may comprise an extruded profile of insulating material, such as suitable thermoplastic materials. It will be appreciated that other suitable materials may be used instead. However, it will be understood that it is not necessary for the hollow core to extend through the whole longitudinal extent of the frame members; it would be sufficient for there to be a hollow portion at the end to receive the associated leg portion of the corner piece.

[0075] The mitre joint 500 comprises a first frame member 520a, a second frame member 520b and an associated corner piece 600. The corner piece 600 has a first leg portion 602a and a second leg portion 602b extending at 90 degrees to one another. Further details about the corner piece 600 are described below with reference to FIG. 15A to FIG. 18.

[0076] The first frame member 520a has a hollow core portion 530a open towards a first end 522a such that the first leg portion 602a is received in the hollow core portion 530a. The first end 522a is formed from the ends of the inner frame element 528a and core frame element 529a. Correspondingly, the second frame member 520b has a hollow core portion 530b open towards a second end 522b such that the second leg portion 602b is received in the hollow core portion 530b. The second end 522b is formed from the ends of the inner frame element 528b and the core frame element 529b.

[0077] Each of the first frame member 520a and the second frame member 520b include respective rafter receiving slots 531a, 531b. The rafter receiving slots 531a, 531b are formed as cut out portions of the corresponding inner frame elements 528a, 528b, and dimensioned to fit around the rafter 700 of the mitre joint 500.

[0078] The respective first end 522a and second end 522b of the frame members are in abutment underneath the corner piece 600, thus forming a joint line which is coplanar with the first end 522a and second end 522b. In the example, the joint line is formed along lower portions of the inner frame elements 528a, 528b and the core frame elements 529a, 529b.

[0079] A mechanical fastening secures the first frame member 520a and the second frame member 520b to the corner piece 600 with the respective first end 522a and second end 522b in abutting engagement. The mechanical fastening (not shown) may be in the form of a first fastener in combination with a second fastener. The first fastener, such as a screw or pin, passes through the first frame member 520a and the second fastener second frame member 520b. A second fastener, such as a screw, may engage the first fastener and clamp the rafter 700 to the first frame member 520a and the second frame member 520b, thereby securing the components of the mitre joint to one another.

[0080] The mitre joint 500 also includes an injection port 580. The injection port 580 is formed as an opening in the first frame member 520a, particularly an opening in the core frame element 529a of the first frame member 520a, proximal to the joint line.

[0081] The mitre joint 500 includes a vent port 590. The vent port 590 is formed as an opening in the second frame member 520b, particularly an opening in the core frame element 529b of the second frame member 520b, proximal to the joint line.

[0082] Referring now to FIG. 15A and FIG. 15B there is shown the corner piece 600 of the roof assembly mitre joint 500. In FIG. 16, the corner piece 600 is shown engaged with a rafter 700. The corner piece 600 has a first leg portion 602a and second leg portion 602b arranged at 90 degrees to one another. The first leg portion 602a and the second leg portion 602b meet along an intersection axis, where the intersection axis is ±45 degree angle relative to the longitudinal axes of the first leg portion 602a and the second leg portion 602b. When secured in the mitre joint 500, the intersection axis of the corner piece 600 is parallel to the joint axis.

[0083] The corner piece 600 includes an upper face 605 and an opposing lower face 606. The lower face 606 includes a first recess 610. A primary portion 610a of the first recess 610 extends along the lower face 606 so as to substantial align with the joint line of the first frame member 520a and the second frame member 520b when the corner piece 600 is secured in the mitre joint 500. In addition, two secondary portions 610b of the first recess 610 extend partially along respective inner edges of the first leg portion 602a and the second leg portion 602b.

[0084] The upper face 605 includes an engaging surface 607 for contactingly engaging a proximal end portion 702 of a rafter 700 of the roof assembly. The engaging surface 607 includes a guide means 608 configured to align the proximal end portion 702 within the mitre joint 500. In the examples, the guide means 608 is an elongate rib, that is aligned along the intersection axis of the corner piece 600. The elongate rib is received into a slot in the proximal end portion 702 of the rafter 700 so that the longitudinal axis of the rafter 700 is aligned with the intersection axis, and thereby aligned with the joint axis.

[0085] The upper face 605 includes a pair of second recesses 612. The pair of second recesses 612 are provided on the engaging surface 607 of the corner piece 600 and arranged so that, when the rafter 700 contacts the engaging surface 607, the rafter 700 covers each second recess 612. In this way, with the rafter 700 secured to the first frame member 520a and second frame member 520b, the proximal end portion 702 of the rafter 700 is in abutment with the engaging surface 607. The proximal end portion 702 and the second recesses 612 together define second closed channels.

[0086] The corner piece 600 includes a locating tab 615 adjoining the corner piece 600 at an inner intersection of the first leg portion 602a and second leg portion 602b. The inner intersection is at an inner end of the intersection axis. The locating tab 615 is spaced apart from each of the first leg portion 602a and the second leg portion 602b to provide eaves receiving slots 641a, 641b to receive portions of the associated first frame member 520a and second frame member 520b.

[0087] The corner piece 600 includes a first bore 631. The first bore 631 provides fluid communication through the corner piece 600. As shown particularly in FIG. 17, the first bore 631 extends from an outer face of the first leg portion 602a to the lower face 606, in particular to the first recesses 610 in the lower face 606.

[0088] The first frame member 520a, second frame member 520b and the corner piece 600 together define a first closed channel along a portion of the joint line. In some embodiments, for example as shown in the example of FIG. 13 to FIG. 18, the closed channel includes the first recess 610 formed in the corner piece 600. In other embodiments (not shown), the closed channel includes recesses in each of the first frame member 520a and second frame member 520b. In yet other embodiments (not shown), the closed channel may be formed as a combination of these aspects; one portion being defined by a recess in the corner piece and another portion being formed as recesses in the respective frame members.

[0089] An injection port 580 is in fluid communication with the first closed channel from an exterior of the mitre joint 500. In particular, the first bore 631 at the outer face of the first leg portion 602a is aligned with the injection port 580. The injection port 580 allows solidifying liquid sealant to be injected into the injection port 580, through the first bore 631 so as to fill the closed channel on the lower face 606 of the corner piece 600 by flowing into and along it whilst in liquid form. Subsequently, the sealant solidifies and forms a sealing bead about the interior periphery of the joint line.

[0090] The corner piece 600 includes a third bore 633. The third bore 633 provides fluid communication through the corner piece 600. As shown particularly in FIG. 17, the first third bore 633 extends from the lower face 606, in particular to the first recess 610 in the lower face 606, to an outer face of the second leg portion 602b.

[0091] A vent port 590 is preferably provided, in fluid communication with the closed channel, to allow air in the closed channel to vent out as the solidifying liquid sealant is injected. In particular, the vent port 590 the third bore 633 at the outer face of the second leg portion 602b is aligned with the vent port 590. By locating the vent port 190 on an exterior of the joint, proximal to injection port 580, a user can be assured that when they see sealant flow out of the vent port 590 the entire closed channel has been filled and the sealing bead has thus been fully formed.

[0092] The corner piece 600 also includes a pair of second bores 632. Each second bore 632 provides fluid communication through the corner piece 600. As shown particularly in FIG. 17 and FIG. 18, each second bore 632 extends from the lower face 606 to the upper face 605, in particular from the first recess 610 to one of the second recesses 612. The second bores 632 thereby provide fluid communication from the lower face 606 of the corner piece 600 to the second closed channels, defined by the proximal end portion 702 and the second recesses 612. In this way, the second bores 632 allow solidifying liquid sealant injected into the injection port 580, to flow from the first bore 631 so as to fill the second closed channel on the upper face 605 of the corner piece 600 by flowing into and each second bore 632 whilst in liquid form. This sealant flows into the second closed channel to abut the proximal end portion 702 of the rafter 700 engaged with the corner piece 600. Subsequently, the sealant solidifies and forms a sealing bead at the proximal end portion 702 of the rafter 700.

[0093] An inner region of each of the eaves receiving slot 641a, 641b forms an elongate recess 642a, 642b. Each elongate recess 642a, 642b provides fluid communication from the first recess 610 on the lower face 606 one of the second recesses 612 on the upper face 605. In particular, each elongate recess 642a, 642b extends from a secondary portion 610b of the first recess 610 to a corresponding second recess 612.

[0094] In this way, the second bores 632 and the elongate recesses provide fluid communication, via several pathways, from the first bore 631 to the hollow core portions 530a, 530b of the first frame member 520a and second frame member 520b. In this way, solidifying liquid sealant injected into the injection port 580, is able to flow from the first bore 631 so as to at fill the first end 522a and the second end 522b by flowing into the respective frame members from the first recess 610 and the second recess 612 whilst in liquid form. This sealant flows around the first leg portion 602a and second leg portion 602b within each hollow core portion 530a, 530b of the mitre joint 500. Subsequently, the sealant solidifies and forms a sealing bead within the respective ends of the frame members.

[0095] The first bore 631, second bores 632, third bore 633 and elongate recesses 642a, 642b together define multiple pathways for fluid communication for flow of solidifying liquid sealant around the mitre joint. As will be appreciated other variations of pathways may be possible by incorporating different combinations, or different numbers, of each of the bores and elongate recesses. For example, there may be only one or more elongate recesses, or one or more second bores, to fluidly communicate between lower face and an upper face of the corner piece. For example, the third bore may fluidly communicate between an upper face, or an inner face, of a corner piece and an exterior of the joint. For example, a mitre joint may include only seals either within one or both ends of frame members, or may include only a seal against a rafter.

[0096] The corner piece 600 includes drainage means on its upper face 605. In the example, the drainage means includes a trough 609 and an outlet 617. The outlet 617 extends in the direction of the intersection axis from an outer intersection of the first leg portion 602a and second leg portion 602b. The trough 609 is provided on the upper face 605 of the corner piece 600 in fluid communication with the outlet 617. The trough 609 is aligned to run along a portion of each of the first leg portion 602a and second leg portion 602b. The portions of the trough 609 meet at the intersection axis. In this way, drainage means is configured to collect unwanted fluid that may collect in the mitre joint 500, such as water condensation within the first frame member 520a, second frame member 520b or the rafter 700. Fluid collected by the drainage means flows under gravity from the trough 609 to the outlet 617, and is then directed out of the mitre joint 500 beyond the roof assembly.

[0097] The skilled person would appreciate that although the glazing unit frame assembly has been described and illustrated in the form of a quadrilateral, and more specifically a square, that it could take many other shapes instead, with corresponding modifications to the component parts, such as the angle between the legs of the corner pieces of the mitre joints, which need not be 90 degrees.

[0098] The skilled person would appreciate that although a roof assembly has been described and illustrated as a fixed-pitch roof assembly with a ridge, that it could take many other shapes or configurations instead with corresponding modifications. For example, the roof assembly may include a fixed pitch wall plate configured to be mounted to a wall, or may include a fixed pitch gable end boss, including frame members and mitre joint as described herein.

[0099] All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be combined in any combination, except combinations where some features are mutually exclusive. Each feature disclosed in this specification, including any accompanying claims, abstract, and drawings, may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed in one example of a generic series of equivalent or similar features.

[0100] The present teachings are not restricted to the details of any of the foregoing examples. Any novel combination of the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be envisaged. The claims should not be construed to cover merely the foregoing examples, but also any variants which fall within the scope of the claims.

Claims

1. A sealed mitre joint comprising:a first frame member, having a first hollow core portion open towards a first end thereof;a second frame member, having a second hollow core portion open towards a second end thereof;a corner piece having a respective first leg portion and a respective second leg portion received in the corresponding first end and second end of the associated frame members;a rafter releasably secured to the first frame member and the second frame member;a mechanical fastening to secure the first frame member and the second frame member to the corner piece with the respective first end and second end thereof in abutment forming a joint line, wherein the first frame member, second frame member and the corner piece together define a first closed channel along a portion of the joint line; andan injection port into the first closed channel, wherein solidifying liquid sealant injected into the injection port fills the first closed channel, forming a sealing bead.

2. The sealed mitre joint of claim 1, wherein the corner piece comprises a first bore to provide fluid communication through the corner piece, from the injection port to the first closed channel.

3. The sealed mitre joint of claim 2, wherein the first closed channel is provided at a lower face of the corner piece, and wherein the first bore extends from an outer surface of the corner piece to the lower surface.

4. The sealed mitre joint of any one of claims 1 to 3, wherein the corner piece comprises an engaging surface for contactingly receiving a proximal end portion of the rafter when the rafter is secured within the mitre joint.

5. The sealed mitre joint of claim 4, wherein the engaging surface comprises a guide means configured to align a proximal end portion of the rafter within the mitre joint.

6. The sealed mitre joint of any one of claims 1 to 5, wherein, with the rafter secured to the first frame member and second frame member, a rafter proximal end portion is in abutment with the engaging surface of the corner piece so that the proximal end portion and the engaging surface together define a second closed channel in fluid communication with the injection port.

7. The sealed mitre joint of claim 6, wherein the corner piece comprises a second bore to provide fluid communication from the first closed channel to the second closed channel.

8. The sealed mitre joint of any one of claims 1 to 7, further comprising a vent port.

9. The sealed mitre joint of claim 8, wherein the corner piece further comprises a third bore configured to provide fluid communication through the corner piece to the vent port.

10. The sealed mitre joint of any one of claims 1 to 9, wherein the first frame member comprises a first receiving slot portion, the second frame member comprises a second receiving slot portion, and wherein the first receiving slot portion and second receiving slot portion together form a rafter receiving slot to mount the rafter in the mitre joint.

11. The sealed mitre j oint of any one of claims 1 to 10, wherein the corner piece comprises an upper face having a drainage means.

12. The sealed mitre joint of claim 1, wherein the mitre joint comprises a fluid pathway through the corner piece from the injection port to at least one of: the first hollow core portion of the first frame member, or the second hollow core portion of the second frame member.

13. The sealed mitre joint of any one of claims 1 to 12, wherein the sealed mitre joint is a roof assembly sealed mitre joint.

14. A sealed mitre joint comprising:a first frame member with a hollow core portion open towards a first end thereof;a second frame member with a hollow core portion open towards a second end thereof;a corner piece with respective first and second leg portions received in the corresponding first and second ends of the associated frame members;a mechanical fastening to secure the first and second frame members to the corner piece with the respective first and second ends thereof in abutment forming a joint line, wherein the first and second frame members and the corner piece together define a closed channel circumscribing the joint line; andan injection port into the closed channel, whereby solidifying liquid sealant injected into the injection port fills the closed channel, forming a sealing bead.

15. The sealed mitre joint of claim 14, wherein the closed channel comprises one or more of:a groove formed in the corner piece;opposed recesses in each of the first and second frame members; ora combination of a groove formed in the corner piece and opposed recesses in each of the first and second frame members.

16. The sealed mitre joint of claim 14 or 15, wherein the injection port is defined on the joint line, across the first and second frame members.

17. The sealed mitre joint of claim 15 or 16, further comprising a vent port out of the closed channel.

18. The sealed mitre joint of any preceding claim, wherein the closed channel has a cross sectional area in the range of 7 to 80 mm2.

19. The sealed mitre joint of any preceding claim, wherein the corner piece comprises a unitary member including both the first and second leg portions.

20. The sealed mitre joint of claim 19, wherein the mechanical fastening comprises a first fastener passing through the first frame member into the first leg of the corner piece, and a second fastener passing through the second frame member into the second leg of the corner piece.

21. The sealed mitre joint of any one of claims 1 to 20, wherein the first and second frame members each comprise an extrusion.

22. A method of forming a sealed mitre joint, comprising:providing a first frame member with a hollow core portion open towards a first end thereof;providing a second frame member with a hollow core portion open towards a second end thereof;providing a corner piece having respective first and second leg portions;inserting the first leg portion into the first end of the first frame member and inserting the second leg portion into the second end of the second frame member such that the respective first and second ends thereof are in abutment forming a joint line, whereby the first and second frame members and the corner piece together define a closed channel circumscribing the joint line;securing the first and second frame members to the corner piece with a mechanical fastening; andinjecting solidifying liquid sealant through an injection port into the closed channel thereby filling the channel and forming a sealing bead.

23. A method of forming a sealed mitre joint, comprising:providing a first frame member with a hollow core portion open towards a first end thereof;providing a second frame member with a hollow core portion open towards a second end thereof;providing a corner piece having respective first leg portion and second leg portion;releasably securing a rafter to the first frame member and the second frame member;inserting the first leg portion into the first end of the first frame member and inserting the second leg portion into the second end of the second frame member such that the respective first and second ends thereof are in abutment forming a joint line, whereby the first and second frame members and the corner piece together define a first closed channel along a portion of the joint line;securing the first and second frame members to the corner piece with a mechanical fastening; andinjecting solidifying liquid sealant through an injection port into the closed channel thereby filling the channel and forming a sealing bead.

24. The method of claim 22 or 23, wherein the solidifying liquid sealant comprises a silicone sealant.

25. The method of claim 24 wherein injecting the solidifying liquid silicone sealant comprises inserting the nozzle of a manual applicator tool into the injection port.

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