Field of invention
[0001] The present invention relates to a bracket and cladding apparatus to support cladding
panels at an external region of a building and in particular, although not exclusively,
to a bracket and cladding assembly configured to provide an enhanced thermal barrier
between the external cladding and inner components of the assembly positioned closest
to the building.
Background art
[0002] A common approach to thermally insulate buildings is to apply a ventilated rainscreen
cladding system at the external region of the building. Typically, individual rainscreen
panels are supported on a framework that is attached to the building external wall
structure in which the framework is formed from brackets and rails to create an air
space between the external cladding layer and inner leaf components of the framework
system (typically boards). Commonly, the cavity between the external cladding and
the inner leaf components is ventilated to the outside air to prevent entrapment of
water and avoid humidity and condensation problems. Where it is required to thermally
insulate the building, it is common to include one or more layers of insulation material
behind the cladding panels. Accordingly, the external surface structure of the building
is concealed from the sun, wind and rain to significantly reduce temperature variations
at the external structure and accordingly provide a more controlled external environment
of the building that is advantageous for the thermal efficiency management of the
building interior.
[0003] A variety of different rainscreen panel systems have been proposed in which the external
cladding layer is separated from the building external wall structure via sub-frame
assemblies, intermediate carrier boards and mounting brackets. Such arrangements are
commonly referred to as steel framing systems (SFS). Example disclosures can be found
in
CA 2820970;
WO 2014/204590 and
US 2014/0311064. However, existing systems are not optimised with regard to the thermal insulation
between the external cladding layer and the external face of the building. In particular,
regions of the steel sub-frame and mounting brackets typically provide an effective
thermal bridge between the cladding and the external wall that reduces the effectiveness
of any intermediate insulation material and the air gap between the cladding layer
and the inner leaf boards. Additionally, conventional arrangements are susceptible
to fire damage that may undermine significantly the structural integrity of the cladding
assembly and compromise secure attachment at the external region of the building.
Accordingly, what is required an external cladding arrangement that addresses the
above problems.
Summary of the Invention
[0004] It is an objective of the present invention to provide a rainscreen cladding apparatus
configured to enhance the thermal isolation of inner leaf components of an external
wall cladding structure for a building from the external environment. It is a further
specific objective to provide a mounting assembly having protective external rainscreen
cladding panels that reduces the magnitude by which the mounting frame assembly transfers
heat between the external cladding layers and the building external wall structure
including in particular inner leaf components including for example cover boards,
plaster boards, timber beams and the like.
[0005] It is a further specific objective to provide a bracket for a rainscreen cladding
apparatus that is resistant to degradation on exposure to fire so as to maintain structural
integrity of the support within the cladding apparatus. It is a specific objective
to provide a bracket to reduce the risk of the cladding apparatus moving appreciably
or component parts becoming detached or lose at the external region of the building.
It is a further specific objective to provide a bracket component for a rainscreen
cladding system that is capable of satisfying fire performance standards relating
to external wall structures of buildings including in particular BR 135 and in particular
tests BS 8414.
[0006] The objectives are achieved by providing a bracket forming part of an external panel
based cladding system that reduces the thermal conduction through the bracket and
between the cladding layer and the building wall structure. In particular the objectives
are achieved via configuring the bracket with an insulation layer attached to a contact
face of a foot part of the bracket in which the insulation layer comprises a conductivity
of less than 0.09 W/(m·K) at 10°C. The present bracket is suitable to support outermost
components of the external cladding system including in particular external cladding
panels to form part of a cladding structure. The present brackets are suitable to
form a mounting sub-frame attachable to the external wall structure that may be formed
from cover boards typically formed from Gypsum or other suitable materials. Additionally,
the present bracket is specifically adapted to form part of a steel framing system
(SFS). In particular, the present bracket is suitable for attachment to intermediate
carrier boards that are in turn mounted at the external wall structure via a sub-frame
assembly.
[0007] According to a first aspect of the present invention there is provided a bracket
to form part of an external building cladding assembly, the bracket comprising: a
foot having a contact face to be positioned to face internally towards the building
and attachable to a structural element forming part of the cladding assembly or the
building; an attachment element to attach the bracket to an external cladding panel,
an intermediate rail or a mount flange securable to the cladding panel; an insulation
layer attached to the contact face of the foot to sit intermediate the foot and the
structural element; wherein a thermal conductivity of the layer is less than 0.09
W/(m·K) at 10 °C.
[0008] Preferably, the attachment element comprises a neck extending perpendicular or transverse
from the foot, the neck attachable to an external cladding panel, an intermediate
rail or a mount flange securable to the cladding panel. Optionally, the attachment
element comprises a flange, connector, aperture, bolts, screws and/or fitting configured
to be engaged and to lock with a cooperating element provided at the cladding panel,
intermediate rail or mount flange to connect the bracket to such structures as part
of a rainscreen assembly at the building external wall.
[0009] The thermal conductivities of the layer material as described herein are stated at
room temperature or a temperature in the range 20 to 27°C, 23 to 27 °C and in particular
24 to 26°C and are stated where the insulation material is provided at a compressive
load of 13.79 kPa (2psi).
[0010] Optionally, the thermal conductivity of the insulation layer is less than 0.05, 0.04
or 0.03 W/(m·K) at 10 °C. Optionally, the thermal conductivity of the insulation layer
is in the range 0.002 to 0.06 W/(m·K) at 10 °C. Optionally, the thermal conductivity
of the insulation layer is in the range 0.005 to 0.04; 0.005 to 0.03; 0.01 to 0.03;
0.01 to 0.028 or 0.01 to 0.026 W/(m·K) at 10 °C. Preferably, the insulation layer
comprises a silica aerogel material optionally comprising a fibre coating at a first
and/or second surface of the silica aerogel. Optionally, the insulation may be provided
at the bracket as a coating resultant from a coating process. Optionally the insulation
coating is configured to be self-bonding to the contact face of the foot of the bracket
without the need for additional bonding agents or mechanical attachments. Optionally,
insulation layer is attached to the contact face of the foot of the bracket via an
adhesive or mechanical attachments.
[0011] Optionally, the bracket further comprises a detachable mounting base positionable
at the contact face of the foot having a generally planar configuration. Preferably,
the mounting base comprises at least one slot to receive an attachment bolt or the
like. Optionally, the mounting base comprises shoulders projecting upwardly from a
mount face, the shoulders positioned at the corners of the mount face. Optionally,
a thickness of the mounting base including the shoulders is less than a thickness
the insulation layer such that no part of the shoulders is configured to contact the
support substrate to which the insulation layer is attached.
[0012] Optionally, the insulation layer is formed as a pad and comprises a thermal conductivity
that is less than 0.05 W/(m·K) at 10 °C. Optionally, the insulation layer comprises
a silica aerogel and a fibre based insulation material having a conductivity in the
range 0.01 to 0.05 W/(m·K) at 10 °C. Optionally, the insulation layer comprises: synthetic
amorphous silica; methylsilytated silica; polyethylene tetraphthalate or polyester;
fibrous glass.
[0013] Optionally, the insulation layer comprises at least one fire retardant component.
Optionally, the fire retardant comprises any one or combination of the set of aluminium
hydroxide, aluminium oxide hydroxide, antimony (III) oxide, a clay, a clay within
a polymer matrix, an organomodified clay, montmorillonite or compounds or materials
including aluminium, phosphorous, nitrogen, antimony, chloride, bromine, magnesium,
zinc, a silicate, or calcium silicate.
[0014] Optionally, the flame retardant comprises iron oxide and/or aluminium trihydrate
(aluminium hydroxide Al(OH)
3).
[0015] Optionally, the insulation layer comprises: silica; a fibrous component preferably
fibrous glass; and a flame retardant component. Optionally, the silica is included
at 25 to 65% by weight; the fibrous material is included at 35 to 55% by weight and
the flame retardant component is included at 1 to 20% by weight.
[0016] Optionally, the bracket comprises synthetic amorphous silica at 25 to 45% by weight;
methylsilated silica at 1 to 25% by weight; fibrous glass at 35 to 55% by weight;
iron oxide at 0.5 to 15% by weight; and aluminium trihydrate at 0.5 to 10% by weight.
[0017] Optionally, the flame retardant component comprises calcium silicate. Optionally,
the bracket comprises: synthetic amorphous silica at 25 to 45% by weight; methylsilated
silica at 1 to 25% by weight; fibrous glass at 30 to 50% by weight; calcium silicate
at 10 to 25% by weight.
[0018] Optionally, the bracket comprises a single insulation layer permanently attached
to the foot. Optionally, the insulation layer comprises a thickness in a plane substantially
perpendicular to the foot of between 3 to 15 mm, 5 to 10 mm. Such a thickness is optimised
to provide sufficient thermal isolation between the bracket and an underlying structure
on which the bracket is mounted whilst also maintaining the capability of the bracket
to withstand the loading forces transmitted through the cladding assembly due for
example to wind shear and the weight of the various components of the assembly. Optionally,
the bracket may comprise strengthening flanges projecting rearwardly from a rear face
of the foot to enhance the strength characteristics of the bracket to withstand loading
forces. Optionally, the brackets may comprise ribs projecting from a rear face of
the foot with the ribs extending at least partially through the insulation layer that
enhance the strength characteristics. Optionally, the flanges or ribs comprise the
same or a different material to the bracket and/or insulation material.
[0019] Optionally, the bracket further comprises an adhesive provided between the layer
and the foot such that the layer is non-detachably mounted at the foot. The adhesive
may be a thermal bonding agent, an epoxy or other bonding resin.
[0020] Optionally, the bracket and in particular the foot and the neck comprise an aluminium
or an aluminium based material.
[0021] Optionally, the bracket may comprise an adaptor plate positioned intermediate the
contact face of the foot and the insulation layer. Optionally, the adaptor plate may
be formed as a plate or block component releasably mountable to the foot of the bracket.
The adaptor plate may be attached via the same attachment bolts used to attach the
bracket to a substrate board or separate attachments may be provided including bolts,
screws, pins, lugs, clips and the like. Optionally, the adaptor plate comprises a
thermoplastic material such as polypropylene. Optionally, a thickness of the adaptor
plate is greater than a thickness of the foot. Optionally, the adaptor plate may comprise
a lip extending along a perimeter of the adaptor plate to sit over and about a perimeter
of the foot such that the adaptor plate is configured to overlap onto the foot. Preferably,
the adaptor plate is configured such that no part of the foot is positioned in direct
contact against the substrate board. The adaptor plate is advantageous to provide
structural strength to the bracket by enlarging the footprint and also assist with
the thermal isolation between the bracket and the underlying substrate board.
[0022] Optionally, the bracket may further comprise a retainer having an open structure
to at least partially surround and house the insulation layer, the retainer being
releasably attached to the foot. Preferably, the retainer is formed from elongate
thin webbing so as to define a cage-like structure. The thickness of the cage material
is maintained to a minimum to reduce as far as possible any thermal bridging via the
retainer when mounted in position between the bracket and substrate board. Optionally,
the retainer is formed as a mesh, gauze, ribbed, webbed or strap-like structure.
[0023] Preferably, the retainer comprises attachments to releasably attach to the foot or
adaptor plate to releasably mount the insulation layer in contact with the foot or
the adaptor plate. The attachments may comprise any form of hooks, clips, pins, screws,
bolts, adhesive or the like. Preferably, the attachments comprise a plurality of barbed
fingers projecting from lengthwise and/or widthwise extending perimeter edges of the
retainer.
[0024] According to a second aspect of the present invention there is provided a building
cladding assembly to form an external wall region of a building comprising: a plurality
of cladding panels positionable in an edge-to-edge arrangement to form an external
cladding layer of a building; a plurality of brackets as claimed herein, each attachment
element of each bracket attachable to one of the cladding panels, an intermediate
rail or mount flange securable to the cladding panels, the foot securable to a structural
element forming part of the cladding assembly or the building via the respective insulation
layers.
[0025] Optionally, the assembly further comprises cladding rails attachable to the necks
of the brackets to form a rail support structure on which to mount the cladding panels.
The cladding rails may comprise a head and a tail, with the head extending generally
parallel to the external cladding boards and the tail extending generally parallel
to the neck of the bracket.
[0026] Preferably, the assembly further comprises a plurality of cover boards positionable
against timber beams that form a part of an external region of the building, the feet
of the brackets attachable to the cover boards via the respective insulation layers.
Optionally, the cover boards may comprise acoustic plaster boards and the assembly
may comprise a single layer or a plurality of layers of cover boards at the external
wall of the building.
[0027] Optionally, the assembly may comprise a steel frame sub-assembly (SFS) arrangement
comprising a sub-frame mountable to a plurality of cover boards positioned to form
a part of an external region of the building; a plurality of carrier boards mountable
to the sub-frame to provide a sub-cladding layer separated from the cover boards via
the sub-frame; and wherein the brackets are mountable to the carrier boards via the
respective insulation layers to spatially separate the external cladding layer from
the sub-cladding layer.
[0028] Optionally, the assembly may comprise a first insulation material positionable between
the external cladding layer and the carrier boards. Optionally, the assembly may further
comprise a second insulation material positionable between the carrier boards and
the cover boards. The insulation material may comprise a fibrous based or mineral
based sheet positioned in a gap region between the external cladding panels and the
building cover board and/or the region between a carrier board and the building external
surface where the system is an SFS cladding assembly.
Brief description of drawings
[0029] A specific implementation of the present invention will now be described, by way
of example only, and with reference to the accompanying drawings in which:
Figure 1 is an external perspective view of a bracket forming part of a building cladding
assembly to form an external wall region of a building having a low thermal conductivity
material attached to the bracket to reduce thermal conductivity through the cladding
assembly according to a specific implementation of the present invention;
Figure 2 illustrates the bracket of figure 1 forming a component part within a building
cladding assembly representing an external wall region of a building according to
a specific implementation of the present invention;
Figure 3 illustrates the bracket of figure 1 forming part of a building cladding assembly
according to a further specific implementation that includes a sub-frame with the
brackets mounted on carrier boards positioned intermediate the sub-frame and external
cladding panels;
Figure 4 illustrates an adaptor component attachable to a foot part of the bracket
to mount a low thermal conductivity layer at the bracket according to a further specific
implementation;
Figure 5 is a perspective view of the bracket of figures 1 to 3 according to a further
specific implementation having an adaptor component configured for mounting at a foot
of the bracket;
Figure 6 is a perspective view of the bracket and adaptor of figure 5 attachable to
a retainer at least partially housing an insulation layer according to the further
specific implementation of figure 5;
Figure 7 is an underside perspective view of the retainer and insulation layer of
figure 6;
Figure 8 an upper perspective view of the retainer and insulation layer of figure
7.
Detailed description of preferred embodiment of the invention
[0030] Referring to figure 1 a bracket 100 to form part of a building cladding assembly
for cladding an external wall region of a building comprises generally a foot 101,
a neck 102 extending generally perpendicular from foot 101 and a head 103 provided
at an opposite end of neck 102 relative to foot 101. Foot 101 comprises a generally
planar body having a front face 105 and a rear face 104. A pair of elongate slots
106 extend through foot 101 between faces 105, 104 to receive attachment bolts for
securing bracket 100 in position within the cladding assembly. Neck 102 projects from
front face 105 to separate head 103 from foot 101. According to the specific implementation,
foot 101, neck 102 and head 103 are formed integrally from aluminium so as to provide
a generally rigid structure. Head 103 comprises a pair of opposed plates 111 that
are spatially separated from one another to provide a mouth or gap region 110. One
or both plates 111 are hingeably mounted together at rearward edge 112 such that plates
111 may be resiliently separated at edge 113 to increase the size of mouth 110 when
mounting a flange or tail part of a rail system that in turn supports external cladding
panels.
[0031] According to further specific implementations, head 103 may be formed from a single
piece or component and comprise apertures to receive mounting bolts, pins, screws
etc to secure bracket 100 to a rail or flange supporting the cladding panels. Other
head 103 mechanisms may also be envisaged such as bayonet attachments, tongue and
groove arrangements, click-lock attachments, push fit connections etc.
[0032] Bracket 100 further comprises a thermal insulation layer 107 non-detachably mounted
at foot rear face 104. According to the specific implementation, the low thermal conductivity
pad 107 is attached to rear face 104 via an adhesive such as an epoxy resin. Pad 107
also comprises a pair of elongate slots 114 being dimensioned and positioned to align
respectively with the slots 106 (extending through foot 101) to receive attachment
bolts. According to the specific implementation, pad 107 comprises a material having
a thermal conductivity of 0.010 to 0.030 W/(m·K) at a mean temperature of 23 to 26
°C and as measured as a compressive load of 13.79 kPa. In one implementation, pad
107 comprises Cryogel™ available from Aspen Aerogels, Inc., NA 05132, USA. Pad 107
comprises a thickness in a plane perpendicular to face 104 of 5 mm to 10 mm and incorporates
the silica aerogel material and a flexible fibre coating provided at a front face
108 and/or a rear face 109 of pad 107. An epoxy or thermal bonding agent is provided
to permanently attach pad 107 via front face 108 to the rear face 104 of foot 101.
[0033] Referring to figure 2, bracket 100 is suitable for inclusion within an external rainscreen
cladding system that is configured as an external wall structure of a building. The
building interior is defined by an acoustic plaster board 215 that represents an inner
leaf of the system having a rear face 217 that is internal facing within the building.
Timber studs (beams) 204 are, in turn, mounted to an external facing mount face 216
of plaster board 215. A composite board 203 is secured to a front face 212 of timber
studs 204 via a rear face 213. Accordingly, composite board 203, studs 204 and plaster
board 215 represent inner leaf components of the external wall structure that may
be regarded as an external wall of the building. A plurality of the brackets 100 are
secured directly to a mount face 211 of composite boards 203 (alternatively termed
cover boards) via mating contact with pad rear face 109. Each bracket 100 is secured
to each cover board 203 via attachment bolts 200 that extend through foot 101 having
bolt heads 201 positioned against front face 105. Accordingly, foot 101 is thermally
isolated from cover board 203 via pad 107. Each bracket head 103 is secured to a tail
member 206 that forms a rearward part of a panel mounting rail assembly 205. In particular,
tail member 206 is formed as an elongate plate at least partially received within
mouth 110 between bracket plates 111 so as to be gripped by frictional contact to
securely mount rail 205 at brackets 100. Accordingly, tail member 206 is aligned generally
parallel with bracket plates 111 and neck 102 and generally perpendicular to foot
101, insulation pad 107 and cover board 203. A rail head 207 also extends perpendicular
to tail member 206. Rail head 207 comprises a mount face 214 for positioning in contact
and attachment to a rear face 209 of a plurality of cladding panels 208. Each panel
208 comprises an external face 210 that represents an external-most part of the cladding
assembly. Due to the respective lengths of bracket neck 102, head 103 and tail member
206, a spatial gap 202 is created between cover board 203 and cladding panels 208.
According to a further embodiment, a sheet insulation material may be positioned in
the gap region 202 between cover board mount face 211 and external cladding panel
rear face 209 to enhance the thermal partitioning of external cladding panels 208
and boards 203 and 215.
[0034] Bracket insulation pad 107 is effective to minimise the thermal conductivity from
the external cladding panels 208 to the cover board 203 at the region immediately
behind foot 101. That is, the region of foot rear face 104 would otherwise provide
a thermal bridge to between panels 208 and cover boards 203. By utilising pad 107
of a low thermal conductivity material, bracket 100 thermally isolates the inner leaf
plaster board 215. To further enhance thermal isolation, suitable low thermal conductivity
washers or flanges may be provided under bolt heads 201 to thermally isolate bolts
200, 201 from the metallic foot 101.
[0035] Figure 3 illustrates a further embodiment of the present invention forming part of
a steel framing system (SFS) cladding assembly. According to the further embodiment,
the building external wall is, in part, defined by a sub-frame assembly that comprises
an innermost plaster board 215 as described with reference to figure 2 representing
an innermost component of the assembly. According to the arrangements of figures 2
and 3, a plurality of boards 215 may be provided as the innermost components of the
assembly to provide acoustic insulation in addition to enhanced thermal insulation.
The sub-frame assembly comprises a plurality of lightweight steel frame support members
300 attached directly to mount face 216 of plaster board 215. Cover boards 203 (alternatively
termed a carrier boards) are mounted at an opposite side of the support members 300
via carrier board rear face 213. Accordingly, a spatial gap 304 is created between
carrier boards rear face 213 and plaster boards mount face 216. A plurality of brackets
100 are then attached to a front face 211 of carrier boards 203 via contact between
rear face 109 of insulation pad 107 and carrier board front face 211 as detailed with
reference to figure 2. Accordingly, carrier boards 203 are positioned intermediate
brackets 100 and steel frame support members 300. The external-most layer of cladding
panels 208 are mounted at the brackets 100 via the rail assembly 205 as described
with reference to figure 2. Also, according to the further specific implementation,
brackets 100 are secured to carrier board 203 via the same bolts 200, 201 as described
with reference to figure 2. According to further embodiments, bolts 200, 201 may be
configured to extend through carrier boards 203 and into respective steel frame support
members 300. As will be appreciated, frame support members 300 may be attached to
carrier boards 203 via respective attachment bolts, screws, pins etc. As with the
embodiments of figure 2, should it be required to enhance the thermal isolation between
cladding panels 208 and plaster board 215, a first layer of insulation material (not
shown) may be positioned within gap region 202 and layered onto front face 211 of
carrier boards 203. Additionally, a second layer of insulation material (not shown)
may be positioned within gap region 304 in contact between carrier board rear face
213 and/or cover board mount face 216.
[0036] According to the embodiments of figures 1 to 3, the present bracket assembly 100
is advantageous via the low thermal conductivity of pad 107 to provide a rainscreen
cladding assembly of reduced total thickness between inner leaf board 215 and cladding
panels 208.
[0037] In one implementation and referring to figure 4 pad 107 may be attached to bracket
100 via an intermediate adaptor indicated generally by reference 400. Adaptor 400
comprises a generally planar base 401 having an underside surface 402 and a support
surface 403. Underside surface 402 is configured for positioning against and in contact
with rear face 104 of foot 101 and comprises slots 405 positioned and dimensioned
to correspond to slots 106 to receive attachment bolts so as to anchor bracket 100
to a suitable support substrate (i.e., boards 203). Base 401 comprises four shoulders
404 positioned at each corner 406 of base 401 that project upwardly a relatively short
height/distance from support surface 403.
[0038] Each shoulder 404 is formed as a relatively thin border section projecting from each
corner 406 and extending a short lengthwise and widthwise distance along a part of
the perimeter edge that defines support surface 403. A thickness of each shoulder
401 in the plane of support surface 403 is significantly less than a thickness of
base 401 in a plane perpendicular to the plane of support surface 403. Accordingly,
should any one of the shoulders 404 contact the substrate to which pad 107 is attached
(for example under extreme compression) any thermal bridging effect through shoulders
404 is minimised and may be regarded as negligible. Shoulders 404 are configured to
facilitate mounting of pad 107 on support surface 403 and are not intended to provide
structural support and in particular to enhance the surface area contact between the
bracket and the substrate board 203. The present bracket is constructed such that
the pad rear face 109 provides exclusively the contact of the bracket 100 onto the
support substrate 203 so as to maximise the thermal isolation function of the present
bracket 100. Base 401 and in particular support surface 403 is configured to support
pad 107 (illustrated with dashed lines) with pad 107 having a footprint or surface
area corresponding to that of support surface 403 and the rear face 104 of bracket
100. The height of each shoulder 404 is appreciably less than a thickness of pad 107
(in the plane perpendicular to the plane of support surface 403) such that even under
compression, pad 107 provides the exclusive contact and intermediate coupling between
the support substrate 203 and the foot 101. That is under normal loading conditions,
no part of each shoulder 404 is capable of contacting the support substrate.
[0039] A further specific implementation of the bracket and adaptor of figures 1 to 4 is
detailed according to figures 5 to 8. According to the further implementation, bracket
100 comprises the same features as described with reference to figure 1 including
for example but not limited to the foot 101, neck 102, head 103 and associated components
and features. According to the further specific implementation, an adaptor plate 500
is formed from a polypropylene thermoplastic and comprises a support surface 501 for
positioning in contact against the rear face 104 of foot 101. Adaptor plate 500 also
comprises an opposed underside surface 502 for positioning against insulation layer
107. As described with reference to figure 4, a plurality of elongate slots 503 are
formed through plate 500 between the opposed faces 501, 502. Plate 500 also comprises
a raised edge 504 in the form of a lip or step extending around a perimeter of plate
500 along the lengthwise and widthwise extending perimeter edges. Plate 500 and edges
504 are dimensioned to sit over and about foot 101 such that foot 101 is at least
partially housed within the recess defined by the upstanding adaptor plate edges 504.
Elongate slots 503 are dimensioned so as to be co-aligned with slots 114 extending
through foot 101 such that plate 500 is capable of being releasably mountable at foot
101 via the attachment bolts 200.
[0040] Referring to figures 6 to 8, bracket 100 also comprises a retainer indicated generally
by reference 600. Retainer 600 comprises an open or cage-like structure to at least
partially house pad 107 within an internal region indicated generally by reference
605. Region 605 is defined by a plurality of interconnect elongate struts that collectively
define a containing frame having the cage-like structure. In particular, a set of
lengthwise and widthwise extending struts 604b define a perimeter footprint of the
retainer 600 with the lengthwise and widthwise struts 604b connected via corner struts
604c that together define a cuboidal open cage structure defining internal cavity
region 605. The structure is supported by a set of bracing struts 604a that extend
between struts 604b and across side faces of the retainer 600 and a rear face 800.
An opposed contact face 801 of retainer 600 is generally open and is not obstructed
by support struts 604a. Accordingly, with pad 107 located within cavity 605, the majority
and in particular at least 80 or 90%, of the planar pad front face 108 is exposed
for contact against the underside surface 502 of adaptor plate 500. Accordingly, when
retainer 600 is mounted in position and in contact against adaptor plate 500, the
underside rear face 109 of pad 107 is largely exposed for contact against the cover
board 203 when bracket 100 is mounted in position within the external rainscreen cladding
system as described referring to figures 2 and 3.
[0041] Retainer 600 is releasably mountable at adaptor plate 500 via a set of attachment
clips that project from retainer contact face 801. In particular, retainer 600 and
in particular lengthwise and widthwise extending struts 604b comprises fingers 602
that project outward from and perpendicular to front face 108. Each finger 602 comprises
a barb 603 directed inwardly towards pad front face 108. The length of each finger
602 is greater than a thickness of adaptor plate 500 so as to allow barbs 603 to be
resiliently biased against and to hook over the raised adaptor plate edges 504 at
plate face 501. Accordingly, with pad 107 housed within the cage-like retainer 600,
pad 107 may be releasably clipped into contact with the bracket 100 via the mating
of the retainer 600 onto adaptor plate 500 that is in turn secured to foot 101.
[0042] The configuration of figures 5 to 7 is advantageous to provide thermal isolation
of bracket 100 and composite board 203 via the intermediate positioned adaptor plate
500 and pad 107. Adaptor plate 500 also assists with the thermal isolation of bracket
100 and board 203 by providing an additional body of relatively low thermal conductivity
between bracket 100 and board 203. The configuration of adaptor plate 500 and retainer
600 and in particular the cage-like structure of retainer 600 is advantageous to impart
sufficient structural strength to the insulation layer 107 and to avoid loading induced
deflection of the insulation layer assembly when mounted in position within a rainscreen
system of figures 2 to 3. That is, the retainer 600 and the adaptor plate 500 when
coupled together are capable of transmitting load from the bracket 100 to the board
203 via attachment bolts 200. Accordingly, the subject invention is advantageous to
provide both the desired structural attachment strength whilst achieving the desired
thermal isolation of the various components of the rainscreen system of figures 2
to 3.
[0043] Example materials of the thermal isolating pad 107 are detailed below. The following
examples are not limiting and the subject invention includes other alternative specific
implementations having constituent materials that differ from those indicated. The
relative concentrations of the constituent materials may also be selected to suit
specific applications.
Example 1
[0044] Pad 107 comprises a material composition comprising components having thermal insulation
characteristics including in particular silica particulate based materials. Preferably,
the material of pad 107 comprises at least one fibrous component. According to the
example 1, pad 107 comprises a foil cover provided at one or both faces. The constituents
of the material of pad 107 according to example 1 are detailed in table 1.
Table 1 - composition of pad 107 comprising Cryogel™ Z available from Aspen Aerogels,
Inc., MA 01532, USA.
Chemical name |
CAS No. |
Concentration wt % |
Synthetic Amorphous Silica |
7631-86-9 |
25-40% |
Methylsilylated Silica |
68909-20-6 |
10-20% |
Polyethylene terephthalate (PET or polyester) |
25038-59-9 |
10-20% |
Fibrous Glass (textile grade) |
- |
10-20% |
Magnesium Hydroxide |
1309-42-8 |
0-5% |
Aluminium Foil |
7429-90-5 |
0-5% |
[0045] Bracket 100 comprising pad 107 according to the subject invention is advantageous
to provide thermal performance enhancement over existing bracketry arrangements. The
thermally isolating characteristic of the subject bracket 100 is achieved, in part,
as the contact surface area of pad rear face 109 is at least equal to or greater than
rear face 104 of foot 101 such that no part of foot 101 is capable of contacting the
support substrate onto which bracket 100 is mechanically attached. Additionally, due
to the aerogel and fibrous composite material, pad 107 is capable of compression in
use as bracket 100 is secured to the support substrate (board 203) via attachment
bolts 200 without any reduction in the thermal conductivity resistance of pad 107.
[0046] The present pad 107 is further advantageous to provide the desired structural performance
and in particular to withstand shear and torsional forces transmitted through bracket
100 when bracket 100 is installed within an external cladding system according to
figures 2 and 3. That is, bracket 100 due to the choice of material of pad 107 is
not configured to deflect appreciably in a vertical plane due to shear loading and
also not to twist about its longitudinal axis due to torsional forces. Bracket 100
achieves the desired minimal deflection during use as it comprises a single pad only
mounted at one end of the bracket. In one implementation, the pad comprises a density
in a range 0.16 g/cm
3 to 0.2 g/cm
3.
Example 2
[0047] In some specific implementations and under example 2, pad 107 comprises at least
one fire retardant component. According to example 2, pad 107 further comprises a
material composition comprising silica particulate based components having thermal
insulation characteristics and at least one fibrous component including for example
fibrous glass.
[0048] Where the pad 107 comprises a fire retardant composition, the fire retardant may
comprise a metal oxide, a metal hydroxide, aluminium hydroxide, aluminium oxide, aluminium
oxide hydroxide, or compounds including aluminium, phosphorous, nitrogen, antimony,
chlorine, bromine, magnesium or zinc. Optionally, the fire retardant comprises a clay
within a polymer matrix including at least one organomodified clay. Optionally, the
clay comprises a montmorillonite. In some implementations, the fire retardant component
comprises an inorganic compound such as antimony (III) oxide (Sb
2O
3). The constituents of the material of pad 107 according to example 2 are detailed
in table 2.
Table 2 - Composition of pad 107 comprising Pyrogel™ XT-E available from Aspen Aerogels,
Inc., MA 01532, USA.
Chemical name |
CAS No. |
Concentration wt % |
Synthetic Amorphous Silica |
7631-86-9 |
30-40% |
Methylsilylated Silica |
68909-20-6 |
10-20% |
Fibrous Glass (textile grade) |
Not Applicable |
40-50% |
Iron Oxide (iron (III) oxide) |
1309-37-1 |
1-10% |
Aluminium Trihydrate (aluminium hydroxide) |
21645-51-2 |
1-5% |
Optional additional components |
- |
Balance |
[0049] In specific implementations, pad 107 is configured to withstand high temperature
environment typically associated with a fire. Preferably, the fire retardant is included
at a concentration of 1 to 20% by weight. The flame retardant is configured to provide
a pad 107 that does not disintegrate or decompose when exposed to temperatures of
up to 650 °C. Accordingly, in such implementations, bracket 100 is configured to exhibit
no or only minor deflection under loading (as would typically be encountered when
bracket 100 is mounted within the cladding systems of figures 2 and 3) during and
following exposure to fire. Accordingly, the structural integrity of the external
cladding systems of figures 2 and 3 is maintained even in the event of a fire at the
external cladding assembly enabling bracket 100 to satisfy further international standards
such as EN 13501 (BR 135)
- Fire Performance of External Thermal Insulation for Walls of Multistorey Buildings. In particular the present bracket 100 comprising a material of example 2 (Pyrogel™)
is capable of satisfying the (BR 135) BS 8414 and EN 1364-1/2 test criteria. According
to example 2, pad 107 does not comprise a foil cover provided at one or both faces.
Example 3
[0050] Example 3 is a variation of example 2 in which pad 107 comprises at least one fire
retardant component in addition to comprising silica particulate based components
having thermal insulation characteristics and at least one fibrous component including
for example fibrous glass.
[0051] The fire retardant may comprise a silicate, belite, calcium monosilicate, calcium
hydrosilicate, calcium metasilicate, calcium orthosilicate, grammite, or Ca2SiO
4. The constituents of the material of pad 107 according to example 3 are detailed
in table 3.
Table 3 - Composition of pad 107 comprising Spaceloft™ A2 available from Aspen Aerogels,
Inc., MA 01532, USA.
Chemical name |
CAS No. |
Concentration wt % |
Synthetic Amorphous Silica |
7631-86-9 |
30-40% |
Methylsilylated Silica |
68909-20-6 |
5-15% |
Fibrous Glass (textile grade) |
Not Applicable |
35-45% |
Calcium Silicate |
13983-17-0 |
15-20% |
[0052] In specific implementations, pad 107 is configured to withstand high temperature
environment typically associated with a fire. Preferably, the fire retardant is included
at a concentration of 1 to 30% by weight. The flame retardant is configured to provide
a pad 107 that does not disintegrate or decompose when exposed to temperatures of
up to 650 °C. Accordingly, in such implementations, bracket 100 is configured to exhibit
no or only minor deflection under loading (as would typically be encountered when
bracket 100 is mounted within the cladding systems of figures 2 and 3) during and
following exposure to fire. Accordingly, the structural integrity of the external
cladding systems of figures 2 and 3 is maintained even in the event of a fire at the
external cladding assembly enabling bracket 100 to satisfy further international standards
such as EN 13501 (BR 135)
- Fire Performance of External Thermal Insulation for Walls of Multistorey Buildings. In particular the present bracket 100 comprising a material of example 3 (Spaceloft™)
is capable of satisfying the (BR 135) BS 8414, and EN 1364-1/2 test criteria as an
A2 rating and ASTM E 84 fire test as a Class A rating. According to example 3, pad
107 does not comprise a foil cover provided at one or both faces.
[0053] The present fire retardant pad 107 according to examples 2 and 3 is advantageous
to withstand shear and torsional forces transmitted through bracket 100 (when mounted
within an external cladding system according to figures 2 and 3) and not to deflect
appreciably in a vertical plane due to shear loading and also not to twist about its
longitudinal axis due to torsional forces during and after exposure fire at high temperatures
of up to 650 °C. Such a configuration is achieved as the pad 107 does not disintegrate
and maintains substantially its pre-fire physical and mechanical characteristics and
composition.
1. A bracket to form part of an external building cladding assembly, the bracket comprising:
a foot having a contact face to be positioned to face internally towards the building
and attachable to a structural element forming part of the cladding assembly or the
building;
an attachment element to attach the bracket to an external cladding panel, an intermediate
rail or a mount flange securable to the cladding panel;
an insulation layer attachable to the contact face of the foot to sit intermediate
the foot and the structural element;
wherein a thermal conductivity of the layer is less than 0.09 W/(m·K) at 10 °C; and
wherein the insulation layer comprises:
• silica;
• fibrous glass; and
• a flame retardant component being iron oxide and/or aluminium trihydrate (aluminium
hydroxide Al(OH)3).
2. The bracket as claimed in claim 1 when the thermal conductivity is less than 0.05
W/(m·K) at 10 °C; is less than 0.03 W/(m·K) at 10 °C or is in the range 0.01 to 0.03
W/(m·K) at 10 °C.
3. The bracket as claimed in any preceding claim wherein the insulation layer comprises
a silica aerogel.
4. The bracket as claimed in any preceding claim wherein the insulation layer comprises
a fibrous component.
5. The bracket as claimed in any preceding claim wherein the silica is included at 25
to 65% by weight; the fibrous material is included at 35 to 55% by weight and the
flame retardant component is included at 1 to 20% by weight.
6. The bracket as claimed in 5 comprising:
• synthetic amorphous silica at 25 to 45% by weight;
• methylsilated silica at 1 to 25% by weight;
• fibrous glass at 35 to 55% by weight;
• iron oxide at 0.5 to 15% by weight; and
• aluminium trihydrate at 0.5 to 10% by weight.
7. The bracket as claimed in any one of claims 1 to 4 wherein the flame retardant component
comprises calcium silicate.
8. The bracket as claimed in 7 comprising:
• synthetic amorphous silica at 25 to 45% by weight;
• methylsilated silica at 1 to 25% by weight;
• fibrous glass at 30 to 50% by weight;
• calcium silicate at 10 to 25% by weight.
9. The bracket as claimed in any preceding claim wherein the insulation layer comprises
a thickness in a plane substantially perpendicular to the foot of between 3 to 15
mm.
10. The bracket as claimed in any preceding claim wherein the attachment element comprises
a neck extending perpendicular or transverse from the foot, the neck attachable to
an external cladding panel, an intermediate rail or a mount flange securable to the
cladding panel wherein the foot and the neck comprise aluminium or an aluminium based
material.
11. The bracket as claimed in any preceding claim further comprising an adaptor plate
positioned intermediate the contact face of the foot and the insulation layer.
12. The bracket as claimed in claim 11 wherein the adaptor plate comprises a thermoplastic
material.
13. The bracket as claimed in claims 11 or 12 wherein a thickness of the adaptor plate
is greater than a thickness of the foot.
14. The bracket as claimed in any one of claims 11 to 13 wherein the adaptor plate comprises
a lip extending along a perimeter of the adaptor plate to sit over and about a perimeter
of the foot such that the adaptor plate is configured to overlap onto the foot.
15. A building cladding assembly to form an external wall region of a building comprising:
a plurality of cladding panels positionable in an edge-to-edge arrangement to form
an external cladding layer of a building;
a plurality of brackets as claimed in any preceding claim, each attachment element
of each bracket attachable to one of the cladding panels, an intermediate rail or
mount flange securable to the cladding panels, the foot securable to a structural
element forming part of the cladding assembly or the building via the respective insulation
layers.