A bracket assembly

Abstract

The present invention provides a bracket assembly (1) for attaching a building cladding assembly to a substructure of a building. The bracket assembly (1) comprises a bracket (2) having a foot (6) to be secured to a substructure of a building, a none combustible thermally insulating pad (3) positioned against a proximal face of the foot (6), a non-combustible shim (4) positioned against a proximal face of the pad (3) and one or more retaining means (15, 16) extending through the shim (4) and the thermally insulating pad (3) to the foot (5), to retain the shim (4) in place sandwiching the thermal insulation pad (3) to the foot (6) of the bracket (2). The invention provides a bracket assembly (1) which may comprise only of non-combustible materials.

Description

[0001] A Bracket Assembly

[0002] The present invention relates to a bracket assembly for attaching to a substructure of a building, to support a cladding assembly of the building.

[0003] The energy used in the heating or cooling of buildings significantly contributes to man made greenhouse gases and both new buildings, and older buildings subject to renovation, are in many jurisdictions required to satisfy stringent and evolving energy efficiency and insultation standards.

[0004] For efficiency, in terms of both cost of materials and labour, new buildings, and particularly larger new buildings such as office blocks, often employ exterior cladding assemblies applied over a substructure of the building. The same applies in respect of older buildings being renovated, and here the substructure of the building may be what was previously an outer wall of the building.

[0005] Exterior cladding assemblies normally comprise a framework structure coupled to the exterior of a substructure of a building by brackets, the brackets extending between the substructure and the framework structure supporting exterior cladding panels. The exterior cladding panels can be engineered to provide various aesthetic characteristics, in addition to having weather resistant properties, for example the cladding panels and frame structure can form a rainscreen system.

[0006] The cladding panels may have some thermal insultation properties, but they will often comprise of panels having very low thermal insultation properties, which panels, for example, may be metal panels or may comprise relatively thin layers of stone. Regardless of the type of panel to be supported by the frame structure, there will normally be provided a thermal insultation layer between the panels / framework structure and the substructure of a building.As thermal insultation of buildings has improved, both to the walls, floors and roofs of buildings, it has been found that thermal losses from a building, resulting from conduction through brackets extending from a substructure of a building to a frame structure, can result in up to thirty percent of the heat loss or heat absorption of the building. This is because the brackets are normally formed of a thermally conductive metal and they thus provide a good thermal path, or thermal bridge, through any insultation material placed between the framework structure and the substructure of the building.

[0007] To address this, it is known to employ thermal insultation pads between a foot of a bracket and a substructure of a building and examples of such systems are disclosed in UK Patent Applications having Publication Nos. GB 2559905 A and GB 2583558 A. These known systems have significantly improved thermal efficiencies, with the thermally insulating pad providing a thermal break between the building and the cladding assembly. With these known systems it is however important that the thermally insulating pad be reliably retained in place against the foot of the bracket at all times, because an installer installing the bracket will typically be working from scaffolding or a mechanical hoist, and will normally need to hold the bracket assembly with just one hand, while using their other hand to use a tool to insert fastenings through the bracket assembly, to secure the bracket assembly to the substructure of a building.

[0008] With the above mentioned known systems, to reliably retain the pad in place against the foot of the bracket, the pad may be housed in a cardboard box, with a layer of adhesive applied between a foot of the bracket and the cardboard box to retain the carboard box and thus the pad in place. The cardboard box is employed because it is difficult to reliably bond the material of the pad directly to the foot of the bracket and because any adhesive applied directly to the pad may penetrate the pad to such an extent as to degrade the thermal insulation properties of the pad. An alternative method of securing the pad to the foot of the bracket uses a cardboard sleeve, which sleeve is slid over both the foot of the bracket and the thermal insulating pad, sandwiching the thermally insulating pad against the foot ofthe bracket. A further alternative method uses a plastic cage placed over the thermally insulating pad, which plastic cage clips over the foot of the bracket and thus this again retains the pad sandwiched against the foot of the bracket.

[0009] All the above alternatives, provide a relatively inexpensive means of retaining the thermally insulating pad in place, without creating a thermal bridge across the thermally insulating pad. However, to avoid creating a thermal bridge across the pad, adhesive must be used in combination with a cardboard box, or alternatively a sleeve or cage must be used, all of which have a low thermal conductivity to avoid establishing a thermal bridge across the insulation pad. It is for this purpose that inexpensive materials having a low thermal conductivity, such as cardboard and plastic are used to form the box, sleeve and the cage respectively.

[0010] It is an object of the present invention to provide an improved bracket assembly of the above type.

[0011] According to a first aspect of the present invention there is provided a bracket assembly for attaching a building cladding assembly to a substructure of a building, the bracket assembly comprising a bracket having a proximal end in the form of a foot arranged to be secured to a substructure of a building and a distal end opposite the proximal end to be attached to and to support a framework structure of a cladding assembly, the bracket assembly further comprising a none combustible thermally insulating pad positioned against a proximal face of the foot of the bracket, a non-combustible shim positioned against a proximal face of the pad and one or more retaining means extending through or from the shim and through the thermally insulating pad and extending into or through the foot of the bracket, to retain the shim in place and sandwich the thermal insulation pad between the shim and the foot of the bracket, wherein each retaining means comprises a pin or tube.A bracket assembly in accordance with the present invention permits the thermally insulating pad to be reliably retained in place against the foot of the bracket and thus permits an installer to hold only the bracket, without the need to hold the thermal insulation pad, and thus avoids the need for the installer to place their hands in a position where they could become trapped between the foot of the bracket and the substructure of the building, as the bracket is clamped into place. However, unlike with the known systems described above, this is possible with the present invention without the need to use adhesive, a cardboard box or sleeve, or a plastic cage, which are all combustible materials which may not be desirable in a cladding system, noting here that the thermally insulating pad itself will be made of a non-combustible material such as Silica Aerogel manufactured by Aspen Aerogels Incorporated. It may also be desirable to avoid the use of cardboard, which may subsequently rot and encourage the growth of mould or fungus.

[0012] The present invention utilises a thin non-combustible shim which extends across the proximal face of the thermally insulating pad and which can have a footprint that matches the footprint of the thermally insulating pad. The shim can have a high thermal conductivity and can thus be in the form of a thin metal sheet which will have sufficient stiffness to retain the thermally insulating pad in place. The shim can thus be thin enough so as to not interfere, to any material extent, with the fastening of the foot and thermal pad to the substructure of the building.

[0013] The reason a thermally conductive material, such as a metal sheet, may be used for the shim, is because the shim does not cross the thermal insulation layer provided by the pad. Instead the shim is retained in place by one or more smaller retaining means, which extend from the pad to the foot of the bracket, directly through the insulation layer, permitting the retaining means to have a totally different structure to that of the shim, a structure that has a very low heat transfer rate resulting not only from the material of the retaining means, but from the shape of the retaining means. This is because the shape, or form, of the retaining means can be significantly different to the planer form of the shim, because the shape of the retaining means does not have to be selected to be able to directly act to holdthe pad in place, but which instead only needs to connect to the shim to anchor the shim in place, not the pad, for the shim will then anchor the pad in place.

[0014] A significant advantage of the present invention is that the retaining means may be a distinct component to the shim.

[0015] The volume of material in the retaining means, in the form of a narrow pin or tube, separate to the shim, may enable the retaining means to be formed of a combustible material, because the volume of that material may be acceptable in a specific application. However, it is preferable for the or each retaining means to comprise a metal pin or metal tube. A metal pin or metal tube is non-combustible and although thermally conductive and providing at least a limited thermal bridge across the thermally insulating pad, because the tensile strength of a metal such aluminium or stainless steel, from which the retaining means may be formed, is relatively high, the cross-sectional area of material forming the retaining means may be very small, resulting in a very low heat transfer rate across the thickness of the thermal insulation pad via the retaining means. This is particularly the case where the retaining means is formed of stainless steel, which is a metal with a relatively low thermal conductivity, one twelfth of that of aluminium, and it is thus preferable for the or each retaining means to be formed of stainless steel.

[0016] Preferably the total heat transfer rate of the or all the retaining means across the thermal pad is less than 25 x 10’3Js’1K’1. Such a low heat transfer rate has a negligible effect overall on the thermal performance of the bracket and this is obtainable using one or more stainless steel retaining means.

[0017] Preferably, the bracket assembly comprises two retaining means, positioned towards respective ones of an opposed pair of side edges of the foot. Two such retaining will thus act to maintain the shim in place across the area of the foot.

[0018] The or each retaining means may comprise a threaded end screwed into a threaded hole in the foot of the bracket, to secure the retaining means to the foot. However, it is preferable for the or each retaining means to extend through the foot, with each retaining means being in the form of a pin or tube with an enlargedportion at each end, which enlarged portion has a greater diameter than the remaining portion of the pin or tube. In this way, the enlarged portions can retain both the shim and the foot on the remaining portion of the retaining means, so that the enlarged portions retain the pad sandwiched between the foot of the bracket and the shim.

[0019] Preferably, the remaining smaller diameter portion of each retaining means extends through a hole in the foot, wherein the remaining portion may slide in the hole in the foot of the bracket. In this manner, if the thermal pad is slightly compressed by the action of fastening the foot of the bracket to the substructure of a building, the retaining means may accommodate this by sliding through the foot without the retaining means becoming distorted, thus the retaining means may continue to keep the shim and the pad correctly aligned with the foot.

[0020] The, or each, retaining means may be in the form of a hollow tube having a enlarged head portion at one end and wherein the tube is flared out at the opposite end to form a second enlarged portion. The or each retaining means may conveniently be formed from the bulb of a pop rivet, or may have the form of a bulb of a pop rivet, where a distal end of the bulb is inserted through the shim, the pad and the foot, before the distal end of the bulb is flared out to trap the shim, the thermally insulating pad and the foot of the bracket between the enlarged head portion and the enlarged flared portion of the bulb.

[0021] Preferably, each retaining means comprises a hollow metal tube, possibly in the form of the bulb of a pop rivet, for a tubular structure offers significant structural strength for a relatively low cross-sectional area of material, making a tubular structure more efficient at minimising heat transfer than a solid pin having an equivalent structural integrity.

[0022] Preferably, the shim is a thin metal plate, metal both being non-combustible and particularly strong and inflexible, relative to other material such as plastichaving similar dimensions, and the shim preferably has a thickness of between 0.3 mm and 0.7 mm.

[0023] Preferably, the thermally insulating pad has a footprint that substantially matches the footprint of the foot of the bracket and wherein the thermally insulating pad is in register with the foot of the bracket. More preferably, the shim has a footprint that also substantially matches the footprint of the foot of the bracket and wherein the shim is in register with the foot of the bracket. In this way the shim may fully support the pad across the entire footprint of the pad.

[0024] The foot of the bracket and the shim may have a plurality of corresponding, in register, apertures, arranged to permit respective fastenings to extend therethrough to secure the bracket to a substructure of a building, with it being possible to push the fastenings through the material of the pad such that the pad seals around the fastenings. Preferably, all components of the bracket assembly, except for the thermally insulating pad which is a non-combustible material, are formed of metal. Therefore, the bracket assembly will inherently be noncombustible which is a desirable feature of cladding systems.

[0025] According to a second aspect of the present invention there is provided a cladding system comprising a plurality of bracket assemblies as described above and a frame structure, wherein the distal end of the bracket assemblies are each arranged to receive sections of the frame structure.

[0026] Two embodiments of the present invention will now be described, with reference to the following drawings, of which:

[0027] Figure 1 is a perspective view of a first embodiment of a bracket assembly 1 in accordance with the present invention;

[0028] Figure 2 is an exploded view of the bracket assembly of Figure 1 ;

[0029] Figure 3 is a partial cross-section along the line A-A and through an eyelet of the bracket assembly of Figure 1 ;Figure 4 is a perspective view of an alternative embodiment of a bracket assembly in accordance with the present invention; and

[0030] Figure 5 is an exploded view of a bracket assembly of Figure 4.

[0031] Referring to Figures 1 and 2, a bracket assembly indicated generally as 1 comprises a bracket 2, a thermally insulating pad 3 and a shim (thin metal plate) 4. The bracket 2 has a proximal end 5 arranged to be secured to a building, which proximal end is in the form of a foot 6 having a three apertures 7 therethrough, through which fastenings (not shown) may be inserted to retain the foot 6 of the bracket 2 in place on a substructure of a building. Extending away from the foot 6 is a neck portion 8 of the bracket 2, which extends to a head portion 9 towards a distal end 10 of the bracket 2. The head portion 9 comprises two parallel plates 9a and 9b forming a U-shaped channel 11 , which is shaped to receive a flange or tail part of a rail (not shown) of a framework structure of a cladding assembly of a building (not shown) which is to be suspended by the bracket 2. The bracket 2 may be formed from extruded aluminium or stainless steel.

[0032] Referring now the thermal pad 3, this has a footprint that matches the footprint of the foot 6 of the bracket 2 and the pad 3 comprises of a noncombustible thermally insulating material such as Silica Aerogel manufactured by Aspen Aerogels Incorporated.

[0033] The pad 3 has a number of apertures 12 formed in it, into each of which is inserted a non-compressible insert 13, which inserts may be formed of a ceramic and which may be in the form of a ceramic bead. The thermally insulating pad 3 may have any desired thickness depending on the desired insulation properties of the pad 3, but in the illustrated example it has a thickness, in a non-com pressed state, of 10 mm. The inserts 13 will similarly have a depth of 10 mm, or a depth that matches the uncompressed thickness of the thermally insulating pad 3, so that the inserts 13 prevent compression of the thermal insulation pad 3, which would otherwise reduce the insulation properties of the thermal insulation pad 3 when the bracket assembly 1 is fastened to a substructure of a building. To retain thethermally insulating pad 3 in place, there is provided the shim 4 which sandwiches the thermally insulating pad 3 between the shim 4 and the foot 6 of the bracket 2, with the shim 4 again having the same footprint as the foot 6 of the bracket 2. The shim 4 also has apertures 18, corresponding to the aperture 7 in the foot and in register with the apertures 7 in the foot.

[0034] The shim 4 may be 316 grade stainless steel sheet, with a thickness of between 0.3 mm and 0.7 mm and more preferably with a thickness of 0.5 mm. The stiffness of the shim 4 is sufficient for it to sandwich the thermal insulating pad 3 to the foot 6 of the bracket 2 when held in place by two eyelets 15 and 16. The eyelets 15 and 16, in the illustrated embodiment, extend through respective holes 17 and 18 in the shim 4, through holes the eyelets 15 and 16 will make when pushed through the thermally insulating pad 3 and holes 19 and 20 in the foot 6 of the bracket 2. The eyelets 15, 16 are described in greater detail below with reference to Figure 3. However, as an alternative to the disclosed embodiment, the eyelets could be fixed to, or extend from, either of the shim 4 or foot 6. Also the eyelets are shown to be in the form of hollow tubes, which is much preferred for their structural rigidity for a given cross section of material, but they could be in the form of narrow solid pins.

[0035] When the bracket assembly has been assembled as shown in Figure 1 , the bracket assembly 1 may be shipped assembled to a site and handled on a site as a complete assembly, ensuring that the thermally insulating pad 3, together with any inserts 13, are correctly assembled on the foot 6 of the bracket 2 prior to the bracket assembly 1 being fixed to a substructure of a building. The bracket can then be fixed, as a single assembly, by means of one or more fastenings being inserted through the apertures 7 of the foot, which bracket assembly, once secured to the substructure of a building by the one or more fastenings, may have a rail of framework structure of a cladding assembly secured in the channel 11 towards the distal end of the bracket 2.Referring now to Figure 3, a partial section along the line A-Aof Figure 1, this shows an eyelet 16 extending through hole 18 in shim 4 and forming a hole 21 through the material of the thermally insulating pad 3, before passing through hole 20 in the foot 6 of the bracket 2. The eyelet 16 is formed from stainless steel but could be formed from another metal such as aluminium. However stainless steel is much preferred because the thermal conductivity is one twelfth of that for aluminium. In the present example, the eyelet is formed from the bulb of a pop rivet after the pin of the pop rivet has been removed.

[0036] To assemble the bracket assembly 1 , the thermally insulating pad 3 is first placed in register on the foot 6 of the bracket 2 and the shim 4 is then placed in register over the pad 3, such as to sandwich the pad 3 between the shim 4 and the foot 6. A distal end 22 of the eyelet 16 is then inserted through the hole 18 in the shim 4 and then pushed through thermally insulating pad 3 to form hole 21 , prior to the eyelet 16 emerging through hole 20 in the foot 6, with the enlarged head portion 23 of the eyelet 16 seating against proximal face of the shim 4. In this position, a compressive force is then applied to the ends of the eyelet 16, to cause the distal end 22 of the eyelet to distort and form a flange 24, as seen in Figure 3, acting to retain the eyelet in place in the foot 6 and to thus retain the shim 4 and thermally insulating pad 3 in place, as shown in Figures 1 and 3.

[0037] The eyelet 16 only has to be compressed sufficiently to produce a relatively small flange 24, because the purpose of the eyelet is solely to retain the shim 4, and thus the thermally insulating pad 3, in place prior to the bracket assembly 1 being installed on a substructure of a building. Once installed on a substructure of a building, the fastenings retaining the bracket 2 in place on the substructure will retain the thermally insulating pad 3 in place and thus at this point the eyelet 16 serves no further purpose. Because the eyelet 16 does not need to be excessively compressed to form the flange 24, the main cylindrical wall 25 of the eyelet does not become distorted to any significant extent during this process of compression and the eyelet 16 remains free to slide through the hole 20 in the foot 6. Thus, when fastenings are tightened to secure the foot 6 of the bracket 2 to asubstructure of a building, if this should act to compress the thermally insulating pad 3, then the foot 6 of the bracket 2 is free to slide down the cylindrical wall 25 of the eyelet 16 so that the eyelet 16 does not interfere with the process of securing the bracket 2 to the substructure of a building.

[0038] The bracket assembly described above, with reference to Figures 1 to 3, is a typical type of bracket assembly that may be used to secure a cladding assembly to a building. In the example given the footprint of the foot 6 of the bracket 2 is 75 mm wide and 62 mm deep with the bracket extending vertically (as shown in Figure 2) 145 mm above the distal face of the thermally insulating pad 3, which pad 3 has a thickness of 10 mm, with the shim 4 having a thickness of 0.5 mm. For a bracket having these or similar dimensions, the eyelet 16 shown in Figure 3, made of stainless steel, has a length of approximately 13 mm with the cylindrical wall having an outer diameter of 3.2 mm and an inner diameter of 1.8 mm. Thus, the cross-sectional area of the stainless steel of the eyelet 16 is 5.5 mm2. This very small cross-sectional area (11 mm2for both eyelets 15 and 16) gives a very low rate of heat transfer Q / t.

[0039] Q / t = kA((T1-T2) / l), where Q is the heat transfer in joules, t is the time, k is the thermal conductivity of stainless steel in this example (15), A is the cross sectional area of both eyelets (11mm2), T1-T2 is the temperature difference between the foot 6 and the shim 4 and I is the separation between the foot 6 and the shim 4 (10mm).

[0040] Thus the heat transfer rate through the eyelets 15 and 16 of this example is 15 x (11 x 10-6(T1 -T2) ) / 10 x 10-3) = 16.5 x 10-3Js’1K1, (16.5 milli watts per degree Celsius).

[0041] The above figure is for the combination of the two eyelets and has a negligible overall effect on the thermal performance of the bracket assembly.

[0042] Referring now to Figures 4 and 5, these correspond to the views of Figures 1 and 2 but show a bracket assembly having a far wider footprint, in this case150 mm. Figures 4 and 5 are included to show that a stainless steel shim 27, still having a thickness of 0.5 mm and retained in place by two eyelets 28 and 29 having the same dimensions and formed of the same stainless steel as in the previous embodiment, may still reliably hold the wider thermal insulating pad 30 in place against the foot 31 of the bracket 32.

[0043] The present invention has been described above by way of example only and it will be appreciated that many modifications may be made to the illustrated embodiments, which modifications may fall within the scope of the following claims and that alternative bracket assemblies may also fall within the scope of the following claims.

Claims

Claims1. A bracket assembly for attaching a building cladding assembly to a substructure of a building, the bracket assembly comprising a bracket having a proximal end in the form of a foot arranged to be secured to a substructure of a building and a distal end opposite the proximal end to be attached to and to support a framework structure of a cladding assembly, the bracket assembly further comprising a none combustible thermally insulating pad positioned against a proximal face of the foot of the bracket, a non-combustible shim positioned against a proximal face of the pad and one or more retaining means extending through or from the shim and through the thermally insulating pad and extending into or through the foot of the bracket, to retain the shim in place and sandwich the thermal insulation pad between the shim and the foot of the bracket, wherein the or each retaining means comprises a pin or tube.

2. A bracket assembly as claimed in Claim 1 , wherein the or each pin or tube is metal.

3. A bracket assembly as claimed in Claim 2 wherein the total heat transfer rate of the, or all, the retaining means across the thermally insulating pad is less than 25 x 10-3Js'1K'1.

4. A bracket assembly as claimed in any preceding claim, comprising two retaining means, positioned towards respective ones of an opposed pair of side edges of the foot of the bracket.

5. A bracket assembly as claimed in any preceding claim, wherein the or each retaining means comprises a threaded end screwed into a threaded hole in the foot of the bracket.

6. A bracket assembly as claimed in any one of claims 1 to 4, wherein the or each retaining means extends through the shim and the foot of the bracket and isin the form of a pin or tube with an enlarged portion at each end, which enlarged portion has a greater diameter than the remaining portion of the pin or tube.

7. A bracket assembly as claimed in Claim 6, wherein the or each retaining means is in the form of a hollow tube having an enlarged head portion at one end and wherein the tube is flared out at the opposite end to form a second enlarged portion.

8. A bracket assembly as claimed in Claim 7, wherein the or each retaining means is formed from the bulb of a pop rivet.

9. A bracket assembly as claimed in Claim 6, 7 or 8 wherein the remaining portion of the or each retaining means extends through a hole in the foot of the bracket and wherein the remaining portion may slide in the hole in the foot of the bracket to accommodate any compression of the thermal pad.

10. A bracket assembly as claimed in any preceding claim, wherein the or each retaining means comprises a hollow metal tube.

11. A bracket assembly as claimed in any preceding claim, wherein the shim is a thin metal plate.

12. A bracket assembly as claimed in Claim 11 , wherein the shim has a thickness of between 0.3 mm to 0.7 mm.

13. A bracket assembly as claimed in any preceding claim, wherein the thermally insulating pad has a footprint that substantially matches the footprint of the foot of the bracket and wherein the thermally insulating pad is in register with the foot of the bracket.

14. A bracket assembly as claimed in Claim 13, wherein the shim has a footprint that substantially matches the footprint of the foot and wherein the shim is in register with the foot of the bracket.

15. A bracket assembly as claimed in any preceding claim, wherein the foot of the bracket and the shim have a plurality of corresponding, in register apertures, arranged to permit respective fastening to extend therethrough to secure the bracket to a substructure of a building.

16. A bracket assembly as claimed in any preceding claim, wherein all components of the bracket assembly, except for the thermally insulating pad, are formed of metal.

17. A bracket assembly as claimed in any preceding claim, wherein the pad is formed of a compressible material.

18. A cladding system comprising a plurality of bracket assemblies as claimed in any proceeding claim and a frame structure, wherein the distal end of the brackets are arranged to receive sections of the frame structure.

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