GB2568473A

GB2568473A - A panel for exterior cladding

Info

Publication number: GB2568473A
Application number: GB1718869.9A
Authority: GB
Inventors: Ward Jenkins Nicholas
Original assignee: Kingspan Holdings IRL Ltd
Current assignee: Kingspan Holdings IRL Ltd
Priority date: 2017-11-15
Filing date: 2017-11-15
Publication date: 2019-05-22
Anticipated expiration: 2037-11-15
Also published as: GB2568473B; GB201718869D0; WO2019096882A1

Abstract

A panel 101 for exterior cladding is polygonal and has an exterior portion and at least two side portions 102, 103 which extend inwardly at an angle to the exterior portion to define a hollow interior. At least one of the two side portions has an intumescent facer 105, 1021 applied thereto. The side portions may have an underlap and an overlap portion, so that in use the overlap of one panel overlaps the underlap of an adjacent panel with a gap therebetween. The intumescent may be applied to the underlap or overlap surfaces and on expansion fills the gap. A cavity barrier system for use with the cladding system may comprise a first cavity barrier 108, deeper than the depth of the panel and received at least partly in the panel interior, and a second cavity barrier 1081 or cavity stop which can be mounted to the structure to be clad. One of the cavity barrier parts may have an intumescent material 110l provided on it. When mounted there is a gap between the two cavity barrier parts which is filled by the intumescent on expansion.

Description

The present invention is direct to panels for exterior cladding and in particular for the improvement of ventilated rainscreen panels with baffled joints.

Background to the Invention

Rainscreen cladding has been incorporated as an aesthetic wall cladding for many centuries. It is applied either during primary construction or as an over-cladding to an existing structure. It consists of an outer weather-resistant decorative skin fixed to an underlying structure by means of a supporting grid, which maintains a ventilated and drained cavity between the facade and the structure. Rainscreen facades are not normally sealed and a ventilation cavity of for example at least 25mm is allowed immediately behind the cladding panel. Insulation can be positioned within the cavity whilst baffled openings to the panel joints and at the top and bottom of the clad areas allow for evaporation of moisture vapour and ventilation drainage. In the last 40 years aluminium both as a single item and in a composite form (widely referred to as Aluminium Composite Cladding or A.C.M. and Aluminium Composite Panel or A.C.P) have become the material of choice. Rainscreen cladding has to be effective aesthetically and functionally to prevent significant amounts of rainwater penetrating into the underlying structure. This type of cladding needs to have longevity and a secure structural performance. Equally and most importantly the structure needs to have robust resistance to the spread of fire. In light of fire safety issues associated with rain screen cladding it is an aim of the present invention to provide a panel and system with improved fire safety performance without a negative impact on the longevity, secure structural performance or aesthetic. It is further an aim of the present invention to enable a more practically achievable creation of robust cavity barrier detailing in installation.

Summary of the Invention

The invention as described herein with reference to the appended claims includes a panel for exterior cladding, the panel being polygonal and having an exterior portion and at least two side portions extending inwardly at an angle to the exterior portion and defining a hollow interior, wherein at least one of the two side portions have an intumescent facer applied thereto.

The intumescent facer applied to the side portions expands when exposed to heat to fill a gap between the panels and slow the progress of a fire along the rear of the cladding. The gap may be baffled.

The at least two side portions may comprise a first side portion and a second side portion, the first side portion comprising an underlap section extending vertically at an angle from the first side portion; and the second side portion having an overlap section extending vertically at an angle from the second side portion and wherein the panel is mountable to a support structure such that when mounted the second side portion of the panel and the first side portion of a vertically adjacent panel have a gap therebetween, the intumescent facer arranged to expand to fill at least a portion of the gap when exposed to heat in the event of a fire. The gap may be baffled.

By filling the gap between the panels progress of a fire is retarded. The free movement of air into the cavity is restricted and thus progress of a fire is retarded.

The gap may comprise a first gap, gl, between the second side portion of the panel and the first side portion of the adjacent panel and a second gap, g2, between the overlap of the panel and the underlap of the adjacent panel. This gap contributes to the baffled joint or open joint nature of the panel and the appearance. Further in normal use the gap provides for air circulation around the panels to ventilate the cladding.

The first side portion may extend a length LI from the exterior portion and the second side portion extends a length L2 from the exterior portion and wherein LI is greater than L2. This aids the installer with the installation of the panels and ensures consistent gaps between the panels.

The intumescent facer may be applied to at least a portion of the surface of the overlap section of the second side portion and wherein the intumescent facer may be arranged to expand to fill the second gap g2 when exposed to heat. By filling the gap g2 fire is retarded from progressing along the vertical cavity provided at the rear of the panelling. The panel may further comprising a cavity barrier arranged within the hollow interior, the hollow interior having a depth dl and the cavity barrier having a depth d2 and wherein d2 is greater than or equal to dl. This cavity barrier further assists in fire retardation.

Where the cavity barrier is incorporated, the overlap section may extend vertically from the second side portion to a height hl and wherein the panel may comprise a ventilation channel of at least a height hl between the second side portion extending inwardly at an angle to the exterior portion and the cavity barrier. The cavity barrier therefore fills the depth of the cavity and the base of the cavity barrier is protected from accumulation of moisture in the cladding panel.

The cavity barrier may comprise mineral wool or stone wool insulation.

The cavity barrier may comprise an intumescent layer.

The exterior portion and the at least two side portions of the panel may be formed from aluminium, zinc, copper or aluminium composites.

The panel may be prefabricated.

A further embodiment of the present invention includes a system for cladding an external surface of a wall comprising a plurality of panels as described above. Each panel may be polygonal and have an exterior portion and at least two side portions extending inwardly at an angle to the exterior portion and defining a hollow interior, wherein at least one of the two side portions have an intumescent facer applied thereto. The at least two side portions may comprise a first side portion and a second side portion, the first side portion comprising an underlap section extending vertically at an angle from the first side portion; and the second side portion having an overlap section extending vertically at an angle from the second side portion, the system may comprise a plurality of mountings for mounting the panels to a support structure such that when mounted the second side portion of the panel and the first side portion of a vertically adjacent panel have a gap therebetween, the intumescent facer arranged to expand to fill at least a portion of the gap when exposed to heat.

When mounted, the gap may comprise a first gap, gl, between the second side portion of the panel and the first side portion of the adjacent panel and a second gap, g2, between the overlap of the panel and the underlap of the adjacent panel. The gaps gl and g2 may be baffled.

The first side portion may extends a length LI from the exterior portion and the second side portion may extend a length L2 from the exterior portion and wherein LI is greater than L2.

The intumescent facer may be applied to at least a portion of the surface of the overlap section of the second side portion and wherein the intumescent facer may be arranged to expand to fill the second gap g2 when exposed to heat.

The system may further comprise a cavity barrier, the cavity barrier comprising a first cavity barrier arranged within the hollow interior of the panel, the hollow interior having a depth dl and the first cavity barrier having a depth d2 and wherein d2 is greater than or equal to dl and a second cavity barrier, the second cavity barrier having a depth d3 and mounted to the external surface of the wall and arranged to extend the depth d3 from the external surface of the wall to within a distance xl of the first cavity barrier when the panel is mounted.

The overlap section may extend vertically from the second side portion to a height h2 and wherein the panel may comprises a ventilation channel of at least a height h2 between the second side portion extending inwardly at an angle to the exterior portion and the first cavity barrier.

The cavity barrier comprises mineral wool or stone wool insulation.

At least one of the first cavity barrier or the second cavity barrier may comprise a cavity barrier intumescent layer and wherein the cavity barrier intumescent layer may be configured to fill the distance xl between the first cavity barrier and the second cavity barrier when exposed to heat.

The system may further comprise a vertical gap cavity barrier having a first vertical cavity barrier arranged within the hollow interior of the panel and a second vertical cavity barrier mounted to the external surface of the wall and arranged to contact the first vertical cavity barrier when the panel is mounted.

The system may further comprising a plurality of horizontal mountings for mounting horizontally adjacent panels to provide a vertical gap between the horizontally adjacent panels.

The system may further comprising a support frame comprising a plurality of horizontal and vertical rails and further comprising a plurality of support frame mountings for mounting the support frame to the external surface of the wall the support frame mountings having a depth d4.

The system may further comprise insulation having a depth approximately equal to d4 and extending from the external surface of the wall.

A further embodiment of the present invention comprises a cavity barrier for a panel as described above, the cavity barrier comprising a first cavity barrier arranged within the hollow interior of the panel, the hollow interior having a depth dl and the first cavity barrier having a depth d2 and wherein d2 is greater than or equal to dl and a second cavity barrier, the second cavity barrier having a depth d3 and mountable to an external surface of the wall and arranged to extend the depth d3 from the external surface of the wall to within a distance xl of the first cavity barrier when the panel is mounted to the external surface of the wall.

At least one of the first cavity barrier or the second cavity barrier comprises a cavity barrier intumescent layer and wherein the cavity barrier intumescent layer is configured to fill the distance xl between the first cavity barrier and the second cavity barrier when exposed to heat.

Brief Description of the Drawings

The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which:Figure 1 is a vertical cross section of two panels with a horizontal joint therebetween in accordance with one embodiment of the present invention mounted to a wall

Figure 2 is a horizontal cross section of two panels with a vertical joint therebetween in accordance with an embodiment of the present invention.

Detailed Description of the Drawings

Rainscreen cladding has been incorporated as an aesthetic wall cladding for many centuries. It is applied either during primary construction or as an over-cladding to an existing structure. It consists of an outer weather-resistant decorative skin fixed to an underlying structure by means of a supporting grid, which maintains a ventilated and drained cavity between the facade and the structure.

Fig.l provides an example of a vertical cross section through aesthetic cladding such as rainscreen cladding mounted on a external wall 114 of a building. The cladding system as shown includes a plurality of panels, 1. These panels are often referred to as cassettes. The panel may be formed from aluminium, zinc, or aluminium composites. The panels as described herein with reference to the claims and the drawings may be prefabricated or components as described below including the cavity barrier and the intumescent facer may be retrofitted to existing panels. In one example the panel may be formed from aluminium composite approximately 4mm thick, however it will be appreciated that the dimensions are not restricted as such.

The panels are mounted to an underlying support structure 106 with mountings 109. The mountings 109 may be clip on or hook on mountings arranged to engage with the panel. The mountings may for example have a bevelled edge to assist an installer in positioning or hooking on the panels to ensure the passage of air to the rear of the rain screen cladding. The mountings as shown are mechanically fixed to the underlying support structure. The underlying support structure is a support frame comprising a plurality of horizontal and vertical rails. The support structure may comprise Hook On “Y” rails for example. Additionally shown in figure 1 are a plurality of support frame mountings 117. These support frame mountings are wall brackets or equivalent mechanical fixing. In one configuration the brackets may be 100 mm brackets. The 100mm wall brackets may be suitable for use with wall insulation of 100mm thickness. These wall brackets may be adjustable. The wall brackets are mechanically fixed to the underlying wall. Mechanical fixings may include screws, self-fixing or otherwise for example.

In the configuration shown in Figure 1 the support frame mountings have a depth d4 the depth being measured from the wall extending towards the exterior cladding. The void created by this depth d4 in the embodiment in Figure 1 incorporates wall insulation 115. In a preferred embodiment the wall insulation is rigid board or dual density slab insulation, however it will be appreciated that it is not restricted as such. Furthermore the wall insulation 115 may be excluded or included in an installed system. The depth of the wall insulation extends to at least the depth d4 in the embodiment shown. Additional layers not shown may include particle board such as cement particle board, a waterproof sheet, and or one or more layers of mineral fibre insulation. The wall insulation may extend at least partially into the support frame. A passage of depth d5 is retained such that the ventilation channels are provided to vent the cladding. In one configuration the depth d5 may be 38mm, however it will be appreciated that it is not restricted as such and alternative depths are envisaged.

The panel for exterior cladding is polygonal and may be a regular polygon or an irregular polygon. The panel 1 has an exterior portion 101. The exterior portion 101 is the external facing portion and provides the weather resistant decorative structure.

The panel also comprises at least two side portions 102,103 extending inwardly at an angle to the exterior portion. The angle may be for example a right angle of 90° however it will be appreciated that this angle is an example only and other angles, obtuse or acute are envisaged.

The two side portions extending from the exterior portion define a hollow interior for the panel or cassette. This hollow interior facilitates the air flow for the rain screen cladding.

The two side portions 102,103 shown in Fig.l define the horizontal edges of the panel such that when installed the first side portion is at the top of an installed panel and the second side portion is at the bottom of the panel, the first side portion.

An intumescent facer 105 is applied to at least one of the two side portions 102, 103. It will be appreciated that the intumescent facer expands in the presence of heat and will expand to fill a gap between two installed panels. Rainscreen cladding of the type shown in Figure 1 is an example of a baffled joint cladding. The use of the intumescent facer in the presence of heat expands to close the gap between vertically adjacent panels and thus retards the progress of fire along the vertical direction of an exterior of a building to which the rainscreen is applied.

In the embodiment of Fig. 1, the first side portion has an underlap section 1021 extending vertically at an angle from the first side portion. This underlap section 1021 is fixed to the underlying support structure 106 along the length of the underlap section. The fixing may be a screw, a bolt or an equivalent mechanical fixing.

In the mounted configuration shown in Figure 1 there is shown a first gap gl between the second side portion of the panel and the first side portion of the vertically adjacent panel. This gap is facilitated by the mountings 109. The configuration of the mountings 109 minimises installer error as their arrangement on the support frame and the bevelled edge assists in the correct installation of the panels and ensures that the horizontal gap between the panels is consistent. The gap gl may for example be 20mm however it will be appreciated that the gap gl may be less than or greater than 20mm in dependence on the building configuration and panel configuration.

A second gap g2 is positioned between the overlap of the panel and the underlap of a vertically adjacent panel. This gap g2 may be for example a 6mm gap and may be a baffled ventilation gap. It will be appreciated that the 6mm gap is an example only and gaps may be greater or less than 6mm independence on the panel configuration and the building configuration.

As outlined above the overlap of the panel extends vertically at an angle from the second side portion and the underlap extends vertically from the first side portion.

The first side portion has a length LI and the second side portion has a length L2. In the configuration shown LI is greater than L2. This configuration contributes to the provision of the gap g2. This further improves reliability as the panels when prefabricated have consistent dimensions and therefore tolerances are tightly controlled. The overlap has a height h2 and the underlap has a height hl, wherein h2 is less than hl. Dimensioning of the height hl and h2 also ensures that the gap gl is consistent and in line with building requirements.

The intumescent facer in Figure 1 is shown on the inner face of the overlap of the panel, facing the underlap. The intumescent facer may be an intumescent tape or paint for example. The intumescent facer may be self-adhesive and applied to the overlap. The self-adhesive tape may be applied on site before the panel is installed, or may be applied in the factory to ensure correct placement. This further facilitates the quality of the panelling and limits installer error. It will be appreciated that the installation on the overlap of the panel protects the intumescent facer from weather associated degradation, however the intumescent facer may also be applied to the underlap. The application of heat causes the intumescent facer to expand to fdl at least the gap g2. In an example configuration with a gap g2 of 6mm, an intumescent strip of 25mm x 1mm may be applied to the overlap portion. It will be appreciated however that this is an example only and other dimensions of facer and gap g2 are envisaged. In Figure 1 the intumescent facer is applied to the inner face of the overlap of the panel, however it will be appreciated that an intumescent facer could also be applied to the outward face of the underlap facing the overlap. A first facer could be applied to the outward face of the underlap and a second facer could be applied to the inner face of the overlap. Under heated conditions such as in a fire, both facers would intumesce to close the gap between the outward face of the underlap and the inner face of the overlap. It will also be appreciated that the intumescent facer could be applied to the first/and or second side portion such that the gap gl would be closed when the facer intumesces.

As an additional fire proofing measure the panel shown in Figure 1 includes a cavity barrier 108. The cavity barrier is arranged within the hollow interior of the panel. The hollow interior has a depth dl and the cavity barrier is configured to fully fill the depth of cassette panel. The cavity barrier is one arrangement is retained within the hollow interior with a self-adhesive tape. The cavity barrier may be retrofitted to existing cassette panels or may be applied in the factory further ensuring reliability of the panels. The cavity barrier has a depth d2. Where d2 is greater than or equal to dl this ensures that the cavity barrier fully fills the depth of the cassette panel In one example the depth d2 may for example be 46mm.

In the system shown in figure 1 a ventilation channel 118 is provided at the base of the panel. The overlap bounds the base on the panel and extends to a height h2 vertically from the second side portion. The cavity barrier sits at the base of the panel supported by the overlap. This provides a ventilation channel having a height approximately equal to h2. For example the height h2 in one configuration is 40mm however it will be appreciated that it is not restricted as such and alternate heights are envisaged. This ensures that if any water gathers at the base of the panel the cavity barrier is clear of this water and the integrity of the cavity barrier is maintained. Excess water drains or evaporates from the ventilation channel 118.

The cavity barrier 108 may comprise mineral wool or stone wool insulation. The cavity barrier 108 may also comprise an intumescent layer 1081. The cavity barrier itself may be intumescent or have an intumescent layer applied thereto such that it expands in the presence of heat to minimise air flow along the rear of the panel.

The cavity barrier in the configuration of Figure lisa two part cavity barrier with the first cavity barrier 108 as described above in relation to the panel and arranged within the hollow interior of the panel. A second cavity barrier 1081 extending from the wall through the insulation and towards the support frame is provided. The second cavity barrier has a depth d3, this depth being greater than the depth of the insulation, d4. When mounted the configuration of the second cavity barrier 1081 and the first cavity barrier 108 is such that a gap xl is provided between an external face of the second cavity barrier and an internal face of the first cavity barrier. The internal face of the first cavity barrier faces the wall of the building and the external face of the second cavity barrier faces in the direction of the exterior of the cladding. The gap xl ensures that the air gap to the rear of the cladding is retained and air can circulate to the rear of the panels. In one configuration the gap xl may be 25mm however it will be appreciated that the gap is not restricted as such and alternative measurements may be accommodated in the system and panel described herein. A cavity barrier intumescent layer 110 is shown applied to the second cavity barrier, however it will be appreciated that this layer may equally be applied to the first cavity barrier. An intumescent layer may be applied to both the first and second cavity barriers. When heat is applied to the first and second cavity barriers the intumescent layers expand to close the gap xl. It will be appreciated that the cavity barriers may be formed from intumescent material which expands to fill the gap in the application of heat.

In Fig. 2 the vertical joint between horizontally adjacent panels is shown in cross section. A vertical gap cavity barrier is shown 111. In the embodiment shown in Figure 2 the vertical gap cavity barrier comprises a first vertical cavity barrier 1111 arranged within the hollow interior of the panel and a second vertical cavity barrier 1112 that is mounted to the external surface of the wall. The second cavity barrier fills the depth of the hollow cavity of the panel and the first cavity barrier extends from the external surface of the wall to engage with the second cavity barrier. This ensures that the vertical joint is not ventilated. Adjacent panels are mounted in the embodiment of figure 2 ensuring a vertical open/baffled joint or gap 113 between the panelling. In an exemplary embodiment the gap may be 20mm however it will be appreciated that it is not restricted as such. The panels are secured to the underlying external surface of the wall 114 of the building using for example a bracket extending from the wall and to which the cladding panels are mounted. In one example, mountings may include a combination of a countersunk bolt 120 and a slide nut 119, and bolt clips 121 extending into the panel. Additional supporting fixings may be incorporated within the hollow interior of the panel to which the bolt clips may be attached. The bracket 116 is secured to the wall using a wall anchor or other equivalent mechanical fixings 117. Optional insulation 115 is included in the cavity formed between the external wall and the panel. The insulation 115 spans only a portion of the distance between the external wall and the panel. A ventilation gap 123 is retained between the insulation and the hollow panel. Optional insulation 122 is further incorporated between the head of the fixing and the exterior surface of the wall. The first and second cavity barriers comprise mineral wool or stone wool insulation. The horizontal mountings 112 determine the ventilation channel or gap 123 between the insulation or wall where insulation is not in place and the panel. The first and second cavity barriers may also comprise an intumescent layer (not shown). While shown in Figure 2 as a two part construct it will be appreciated that the first and second cavity barriers may be a single piece rather than a two part construction extending from the wall to within the hollow cavity. An advantage associated with the two part construct is the ease of construction. A single piece construct for the cavity barrier would appreciably increase the tooling required to accommodate the support structure. The two part cavity barrier facilitates simpler manufacturing and installation.

As an example of the ventilated panelling described above and improved performance in fire safety testing a configuration of the present invention incorporating a 50mm deep 3mm PPC Aluminium cassette panel (for example Booth Muirie BML100 Hidden Plate Hook on Cassette or similar for example an Alpolic A3 ACM Hidden Plate Hook On cassette) with 20mm joints (gl) and a 38 mm cavity (d5), in combination with 100mm Phenolic foam insulation, (for example Kingspan KI5 Phenolic foam insulation or Rockwool Duoslab) and including the two part cavity barrier on a blockwork substrate as described above has been tested according to and achieved BS8414 Standard for Fire performance of external cladding systems and has passed according to BRE135 criteria.

The words “comprises/comprising” and the words “having/including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in 10 any suitable sub-combination.

Claims

1. A panel for exterior cladding, the panel being polygonal and having an exterior portion and at least two side portions extending inwardly at an angle to the exterior portion and defining a hollow interior, wherein at least one of the two side portions have an intumescent facer applied thereto.

2. The panel according to claim 1 wherein the at least two side portions comprise a first side portion and a second side portion, the first side portion comprising an underlap section extending vertically at an angle from the first side portion; and the second side portion having an overlap section extending vertically at an angle from the second side portion and wherein the panel is mountable to a support structure such that when mounted the second side portion of the panel and the first side portion of a vertically adjacent panel have a gap therebetween, the intumescent facer arranged to expand to fill at least a portion of the gap when exposed to heat.

3. The panel according to claim 2 wherein when mounted, the gap comprises a first gap, gl, between the second side portion of the panel and the first side portion of the adjacent panel and a second gap, g2, between the overlap of the panel and the underlap of the adjacent panel.

4. The panel according to claim 3 wherein the first side portion extends a length LI from the exterior portion and the second side portion extends a length L2 from the exterior portion and wherein LI is greater than L2.

5. The panel according to any of claims 3 or 4 wherein the intumescent facer is applied to at least a portion of the surface of the overlap section of the second side portion and wherein the intumescent facer is arranged to expand to fill the second gap g2 when exposed to heat.

6. The panel according to any of claims 2 to 5 further comprising a cavity barrier arranged within the hollow interior, the hollow interior having a depth dl and the cavity barrier having a depth d2 and wherein d2 is greater than or equal to dl.

7. The panel according to claims 5 wherein the overlap section extends vertically from the second side portion to a height h2 and wherein the panel comprises a ventilation channel of at least a height h2 between the second side portion extending inwardly at an angle to the exterior portion and the cavity barrier.

8. The panel according to any of claims 6 or 7 wherein the cavity barrier comprises mineral wool or stone wool insulation.

9. The panel according to any of claims 6 to 8 wherein the cavity barrier comprises an intumescent layer.

10. The panel according to any previous claim wherein the exterior portion and the at least two side portions are formed from aluminium, zinc, or aluminium composites.

1 l.The panel according to any previous claim wherein the panel is prefabricated.

12. A system for cladding an external surface of a wall comprising a plurality of panels each panel being polygonal and having an exterior portion and at least two side portions extending inwardly at an angle to the exterior portion and defining a hollow interior, wherein at least one of the two side portions have an intumescent facer applied thereto.

13. The system according to claim 12 wherein the at least two side portions comprise a first side portion and a second side portion, the first side portion comprising an underlap section extending vertically at an angle from the first side portion; and the second side portion having an overlap section extending vertically at an angle from the second side portion, the system comprising a plurality of mountings for mounting the panels to a support structure such that when mounted the second side portion of the panel and the first side portion of a vertically adjacent panel have a gap therebetween, the intumescent facer arranged to expand to fill at least a portion of the gap when exposed to heat.

14. The system according to claim 13 wherein when mounted, the gap comprises a first gap, gl, between the second side portion of the panel and the first side portion of the adjacent panel and a second gap, g2, between the overlap of the panel and the underlap of the adjacent panel.

15. The system according to claim 14 wherein the first side portion extends a length LI from the exterior portion and the second side portion extends a length L2 from the exterior portion and wherein LI is greater than L2.

16. The system according to any of claims 14 or 15 wherein the intumescent facer is applied to at least a portion of the surface of the overlap section of the second side portion and wherein the intumescent facer is arranged to expand to fill the second gap g2 when exposed to heat.

17. The system according to any of claims 13 to 16 further comprising a cavity barrier, the cavity barrier comprising a first cavity barrier arranged within the hollow interior of the panel, the hollow interior having a depth dl and the first cavity barrier having a depth d2 and wherein d2 is greater than or equal to dl and a second cavity barrier, the second cavity barrier having a depth d3 and mounted to the external surface of the wall and arranged to extend the depth d3 from the external surface of the wall to within a distance xl of the first cavity barrier when the panel is mounted.

18. The system according to claims 17 wherein the underlap section extends vertically from the second side portion to a height h2 and wherein the panel comprises a ventilation channel of at least a height h2 between the second side portion extending inwardly at an angle to the exterior portion and the first cavity barrier.

19. The system according to any of claims 17 or 18 wherein the cavity barrier comprises mineral wool or stone wool insulation.

20. The system according to any of claims 17 to 19 wherein at least one of the first cavity barrier or the second cavity barrier comprises an cavity barrier intumescent layer and wherein the cavity barrier intumescent layer is configured to fill the distance xl between the first cavity barrier and the second cavity barrier when exposed to heat.

21. The system according to any of claims 13 to 20 further comprising a vertical gap cavity barrier having a first vertical cavity barrier arranged within the hollow interior of the panel and a second vertical cavity barrier mounted to the external surface of the wall and arranged to contact the first vertical cavity barrier when the panel is mounted.

22. The system according to any of claims 13 to 21 further comprising a plurality of horizontal mountings for mounting horizontally adjacent panels to provide a vertical gap between the horizontally adjacent panels.

23. The system according to any of claims 12 to 22 further comprising a support frame comprising a plurality of horizontal and vertical rails and further comprising a plurality of support frame mountings for mounting the support frame to the external surface of the wall, the support frame mountings having a depth d4.

24. The system according to claim 23 further comprising insulation having a depth approximately equal to d4 and extending from the external surface of the wall.

25. A cavity barrier for a panel according to any of claims 1 to 11, the cavity barrier comprising a first cavity barrier arranged within the hollow interior of the panel, the hollow interior having a depth dl and the first cavity barrier having a depth d2 and wherein d2 is greater than or equal to dl and a second cavity barrier, the second

5 cavity barrier having a depth d3 and mountable to an external surface of the wall and arranged to extend the depth d3 from the external surface of the wall to within a distance xl of the first cavity barrier when the panel is mounted to the external surface of the wall.

26. The cavity barrier according to claim 25 wherein at least one of the first cavity

10 barrier or the second cavity barrier comprises an cavity barrier intumescent layer and wherein the cavity barrier intumescent layer is configured to fill the distance xl between the first cavity barrier and the second cavity barrier when exposed to heat.