EP2458102A1

EP2458102A1 - A cladding unit

Info

Publication number: EP2458102A1
Application number: EP11188445A
Authority: EP
Inventors: Stephen Philips
Original assignee: Grants of Shoreditch Ltd; Ove Arup & Partners Ltd; Building Research Establishment Ltd
Current assignee: Grants of Shoreditch Ltd; Ove Arup & Partners Ltd; Building Research Establishment Ltd
Priority date: 2010-11-25
Filing date: 2011-11-09
Publication date: 2012-05-30
Also published as: GB201020021D0; GB2485823A

Abstract

A cladding unit (2) comprises a frame (4) supporting a board material (6), wherein the frame (4) comprises a fibre reinforced polymer and the board (6) comprises a composite of mineral and pulp. Optionally, the cladding unit (2) includes a rainscreen (16) provided on an outer face of the cladding unit (2), together with a vapour barrier (10), a breather membrane (14), a fire barrier (22), a gasket (24) and/or insulation (12). The board material (6) preferably comprises calcium sulphate.

Description

The present invention relates to a cladding unit which can be used to form the outer covering of a building. In particular, it relates to a cladding unit which is used to form the wall of a building, including an external vertical wall façade.
Various cladding materials are used for buildings to provide an attractive, weather-proof exterior. They are generally non-structural. For example, the following types of cladding are commonly used: stone, aluminium, ceramic, timber and cement-board. The cladding typically has a timber, steel or aluminium support. This support is generally fixed to a load-bearing block surface, for example. Alternative building facades are provided by curtain-walling and load-bearing block and brick walling.
With the increasing awareness of the thermal performance and sustainability of new buildings, together with a desire to reduce the cost of building materials, the present invention seeks to provide a cladding unit for use in an alternative cladding system.
As a result, the present invention provides a cladding unit comprising a frame supporting a board material, wherein the frame comprises a fibre reinforced polymer and the board material comprises a composite of mineral and pulp.
The present invention is therefore provided by the cladding unit of independent Claim 1 and by the cladding system of Claim 10. The dependent claims specify preferred but optional features.
The cladding unit is preferably non-structural. It is designed to be pre-fabricated. Hence, it is readily installable in new buildings and as a retrofit for existing buildings.
The size of the cladding unit depends on the dimensions and style of the building in question. It may have a height of 2.5 to 6m, for example. It is therefore possible for each cladding unit to span the distance between one or two floors of a building. A typical width of the cladding unit ranges from 1 to 8m.
The board material itself may be formed of a plurality of panels each comprising the mineral and pulp composite. These panels may be adjoined using an adhesive-bonded tongue and groove arrangement. When so joined, the individual panels form a single board having a size as required. This interlocking of adjacent panels enables a wide variety of larger board sizes to be formed, whilst keeping the structural properties of a single board.
The board material is preferably sized to substantially the same overall dimensions as the supporting frame. The board material may be secured to the frame using a mechanical connection, for example. This may involve self-tapping screws, expansion screws or co-aligned nuts and bolts. In a preferred embodiment, the board material is secured to an internal perimeter edge of the frame. Preferably, the board material is located such that if fills a face defined by the frame.
The board material may be provided with one or more apertures which may be used for doors or windows.
The board material is preferably a composite of calcium sulphate and pulp. Preferably the dihydrate form of calcium sulphate is used (this is know as gypsum). Preferably the pulp is paper pulp.
In one embodiment, the board material comprises 85 to 90 wt% gypsum, 5 to 14.5 wt% cellulose fibres and 0.5 to 5 wt% water. In a preferred embodiment, the board material consists of 85 to 90 wt% gypsum, 5 to 14.5 wt% cellulose fibres and 0.5 to 5 wt% water.
Minerals are naturally occurring inorganic substances. Another suitable mineral for forming the board material is calcium silicate.
Pulp is a mixture of cellulose fibres, which may be from wood, fibre crops, waste paper or recycled material. This fibrous material may be prepared by the chemical or mechanical separation of the fibres.
The board material is sufficiently structurally rigid to withstand the forces that will be applied to it when in situ, for example concentrated loads of up to 5kN. It preferably has a thickness of 20 to 80mm, preferably of 30 to 60mm.
The board material preferably has good fire resistance, good sound insulation and low thermal conductivity.
The fibre reinforced polymer (FRP) of the frame is preferably a phenolic resin, a modified acrylic resin (such as Modar ®) or a polyester resin, these resins being reinforced with fibres. Methacrylate polymers are also useful for making the frame. The reinforcing fibres may be glass fibres, carbon fibres, animal fibres (such as spun wool fibre) and plant fibres (including leaf fibres such as flax leaf fibre). In an alternative embodiment, the frame comprises an organic cellulose sugar matrix. The frame may be pulltruded.
The frame is preferably adapted for vertical or substantially vertical use. It is preferably non-structural. The frame is able to provide exceptional strength to weight ratio and good thermal performance. For example, the frame preferably has a thermal conductivity of 0.25 to 0.30 W/mK. In contrast, aluminium supports for cladding used in the prior art have a thermal conductivity of about 160W/mK. Thus, the frame of the present invention has the advantage of reducing thermal bridging. Other advantages of the frame include a low weight (about 70% of that of aluminium) and resistance to corrosion.
The frame is adapted to support the board. At least one face of the board material is preferably flush with one face defined by the frame. The frame may have a thickness of 50 to 350mm, preferably 150 to 250mm .
The frame defines at least one aperture. Internal frame sections may be present to divide the main area defined by the frame into a plurality of apertures. When the frame is upright for use, the frame preferably has a substantially square or rectangular shape. Any internal frame sections present are preferably aligned either horizontally or vertically within the frame.
Insulation, such as one or more insulation blocks or pieces, may be placed in one ore more of the apertures provided in the frame. Alternatively, the insulation may be in the form of one or more layers which cover or partially cover the main area defined by the frame.
The cladding unit of the present invention is relatively thin and lightweight and can be manufactured at a relatively low cost. Moreover, it provides good technical performance and has an acceptably low environmental impact. It is able to be installed quickly and accurately in buildings.
The cladding unit has a face to be directed towards the inside of a building (the inner face) and a face to be directed towards the outside of a building (the outer face). The inner face is preferably provided by the board material which can be surface treated (for example, painted or plastered) depending on the desired presentation of the wall so formed. The outer face is usually required to be weather-proof and water-tight. As such the board material is preferably overlaid with further materials, preferably in the form of layers, which provide the desired properties of an exterior surface of a building.
These further materials may include a vapour barrier and/or a breather membrane. A fire barrier may also be included.
In this respect, the vapour barrier is preferably placed in contact with or close to an outer face of the board material (ie the face to be directed towards the outside of the building).
To ensure the cladding unit is water-tight, an outer rainscreen system may be provided. Preferably, such a rainscreen system comprises a rainscreen and a support means. In an example of such a system, at least one support rail is attached to the face of the board material to support a rainscreen. Preferably the outer face of the cladding unit is provided with a rainscreen layer. An outer rainscreen system enables the face of a building to have a choice of finishes, such as brick, timber and tile.
Preferably, the breather membrane is placed in contact with or close to an inner face of the rainscreen system. The fire barrier, if present, is preferably located adjacent an inner face of the rainscreen system. If both the breather membrane and the fire barrier are present, the fire barrier is preferably located between the breather membrane and the rainscreen.
The present invention also provides a cladding system comprising a plurality of cladding units located adjacent to one another.
To seal adjacent units together in this system, when forming an exterior surface of a building, gaskets may be used. Thus, each cladding unit preferably has a gasket around its perimeter. The gasket is adapted to abut the gaskets of adjacent cladding units to seal the surface formed by the cladding system. This gasket may be fixed to the external perimeter of the frame via mechanical connection means.
When assembling a building, the cladding units are adapted to be placed adjacent to one another, for example both horizontally and vertically. They are therefore able to form a flush surface such as a wall of a building. This wall may be eight cladding units wide by four cladding units high.
The combination of the board material and the frame of the invention provides a cladding unit having a composite structural effect and reduced thermal conductivity compared to prior art systems. The frame provides out-of-plane stiffness and the board material provides in-plane loads. Preferably, the cladding unit has sufficiently good thermal properties to avoid the need for additional thermal breaks, which are typically needed in aluminium or steel cladding systems. In view of these good thermal properties, thick layers of insulation, such as those required in timber-based panels, are not necessarily required, meaning that that the cladding unit may have a relatively low thickness and weight.
An embodiment of the present invention will now be described by way of example only, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 is an exploded perspective view of the frame and the board material;
Figure 2 is an exploded perspective view of one example of a complete cladding unit; and
Figure 3 is a perspective view of the complete cladding unit, partly-exploded to show adjacent layers thereof.

Referring to Figure 1, a cladding unit 2 comprises a frame 4 and a board material 6. The cladding unit has an outer face to be directed towards the outside of a building and an inner face to be directed towards the inside of a building. In the description which follows, faces of the layers used to form the cladding unit are named accordingly.
In the centre of the board material is an aperture 8 for fitting a window therein. The board material is fixed to the frame using nuts and bolts (not shown). Once assembled, a face of the board material (the face directed towards the inside of the building) is flush with the face formed by the frame that is directed towards the inside of the building (the inner side of the frame).
In one example, the board material has a height of 2930mm, a width of 4430mm and a thickness of 40mm; and the supporting frame has a height of 2985mm, a width of 4485mm and a thickness of 200mm.
The board material is calcium sulphate board which preferably has a low thermal conductivity, for example of 0.23 W/mK. In a preferred embodiment, the board material consists of 90 wt% gypsum, 9 wt% cellulose fibres and 1 wt% water. The calcium sulphate board, in one example, is made from about 95% recycled post-industrial waste.
The board material is available from Lindner AG in Germany. The board may be manufactured as follows. Cellulose fibers are extracted from 100% waste paper which has been disintegrated in water. The mash is mixed with water and gypsum, which is recycled waste material out of a combustion gas desulphurization process. The material is compressed in a mould and dehumidified/dried to remove excess water.
The frame may be a Phenolic FRP frame. The frame may be pulltruded. It preferably has a low thermal conductivity, for example of 0.27 W/mK.
The frame is provided with internal frame sections extending both vertically and horizontally, forming an H-type profile and defining five apertures. The central aperture is for fitting a window therein.
Figure 2 shows the frame and board material together with other material layers which are optionally used to form a complete cladding unit.
In Figure 2, the board material 6 is fixed to the frame. On an outer face of the board material, at the inner side of the frame, a vapour barrier layer 10 is provided. It may have substantially the same size and surface area as the board material. It is therefore located between the board material and the internal frame sections. In one example, the vapour barrier layer is made of a polyethylene sheet, which is preferably 1 to 2mm thick.
On the opposite side of the frame, on its outer side, insulation is provided in four of the apertures provided in the frame to form an insulation layer 12. The insulation may be pieces of mineral wool such Rockwool™ insulation.
A breather membrane layer 14 is provided on the outer face of the insulation layer. This breather membrane layer may have substantially the same size and surface area as the board material. In one example, it is made of a polyethylene sheet, which is preferably 1 to 2mm thick.
On the outer face of the breather membrane layer is placed an outer rainscreen layer 16 comprising a plurality of cladding panels. A window 18 is placed in the resulting opening in the composite unit.
Figure 3 shows the layers of the complete cladding unit closer together. Here a cladding support rail 20 is shown. This is mechanically attached to the structure of the cladding unit for supporting the cladding panels; screw and rivet fixings may be used. In this example, the support rail is provided in the form of a number of horizontally-orientated rails on which the cladding panels are mounted. The rails may be aluminium channels.
The cladding panels may be made of 8mm thick glass reinforced concrete panels. Each cladding panel may be between 573 and 600mm high and between 1245 and 1975mm wide. Other materials may also be used for this outer rainscreen: for example wood, brick or tile.
In spaces between adjacent, horizontal support rails, vertically-orientated fire barrier segments 22 are placed, located towards the edge of the cladding unit. The presence of such a fire barrier is optional.
A gasket 24 surrounds the frame of the unit and is used to abut the gaskets of adjacent units, thereby sealing the surface formed by the units. Preferably the gasket is a rubber gasket. It is fitted on the perimeter of the frame.
In forming a cladding system, adjacent cladding units are sealed by the abutting gaskets of neighbouring units.
The resulting cladding unit is weather-tight, has good thermal properties, excellent acoustic performance and high fire resistance.

Claims

A cladding unit (2) comprising a frame (4) supporting a board material (6), wherein the frame comprises a fibre reinforced polymer and the board comprises a composite of mineral and pulp.
A cladding unit as claimed in claim 1, further comprising a rainscreen (16) provided on a face of the cladding unit.
A cladding unit as claimed in claim 1 or claim 2, further comprising a vapour barrier (10) and/or a breather membrane (14).
A cladding unit as claimed in any preceding claim, further comprising a fire barrier (22) and/or insulation (12).
A cladding unit as claimed in any preceding claim, wherein the board material comprises calcium sulphate or calcium silicate.
A cladding unit as claimed in any preceding claim, wherein the frame comprises a phenolic resin, a modified acrylic resin, a methacrylate polymer or a polyester resin.
A cladding unit as claimed in any preceding claim, wherein the fibres in the fibre reinforced polymer are selected from the group consisting of glass fibres, carbon fibres, animal fibres, plant fibres and mixtures thereof.
A cladding unit as claimed in any preceding claim, wherein the board material comprises 85 to 90 wt% gypsum, 5 to 14.5 wt% cellulose fibres and 0.5 to 5 wt% water.
A cladding unit as claimed in any preceding claim, further comprising a gasket (24) on the perimeter of the unit.
A cladding system comprising a plurality of cladding units, as claimed in any preceding claim, located adjacent to one another.