GB2469830A - Building skin comprising overlapping flexible panels - Google Patents

Abstract

A polymer membrane building skin is assembled from prefabricated panel assemblies 101-108, resulting in an appearance similar to a traditional lead roof. Each panel comprises a flexible membrane having a weather surface and a rear surface, the membrane rear surface being bonded along at least one edge to a strip 140/142 relatively rigid material, such as polymer-coated steel. The panel has an un-bonded portion 254 which can be exposed temporarily to allow fixing onto a supporting structure, the un-bonded portion and fixing 170 being re-covered by the membrane in the finished assembly. Side edges of membrane panels overlap and may be welded. Sealing strips 324 are provided at the lower edges for welding to the panel below. Various fixings incorporating weldable membrane material are described for attaching accessories such as capping strips 812 and other accessories to the completed skin, for cosmetic or other purposes.

Description

METHOD OF CONSTRUCTING A BUILDING SKIN, BUILDING SKIN

INSTALLATION AND PANELS FOR USE THEREIN

The invention relates to methods and component panels for use in installing a building skin, meaning the outer layer of a roof structure or wall.

Various materials are known for providing a weatherproof skin to a building, be it a flat or inclined roof or a vertical wall. Functional performance, durability, cost of materials, cost of labour/equipment for installation are all factors in the choice of method and materials. Tiles (shingles) and sheet materials are the common alternatives. Where aesthetic appearance is important, traditional materials may be used, or modern materials adapted to provide the look of traditional materials. The look of a traditional material, for example a lead sheet roof, is a function not only of the material, but also the way it is shaped and applied to the supporting structure.

Modern sheet materials include bituminous felts, polymer membranes such as PVC and the more established PIB (polyisobutylene). PIB and other polymers are also available as coatings on rigid substrate materials, such as steel sheeting. The polymer coating provides a barrier to corrosion of the metal, and can also provide an aesthetically pleasing finish. PIB materials can be obtained in various forms for example from the company Flachdach Technologie GmbH, represented in the UK by FDT (UK) Limited, under the trade mark Rhepanol. The PIB coating on the metal can be sealed to the membrane without the use of separate adhesives, either by application of heat from a hot air gun, or by providing a "self-sealing" interface layer of low molecular weight PIB. This self-sealing layer fuses spontaneously with another PIB surface to which it is applied, even at ambient temperature. In a conventional application, PIB-coated metal may be used as the flashing, for example, around a skin of reinforced PIB membrane.

GB 2448148 A by the present inventor discloses a method to build a skin for a roof with polymer-coated substrate panels that can be interconnected and sealed at joins by lap pieces made of a polymer membrane.

The present invention aims to provide an alternative system for installing a building skin using panels made of modern materials such as polymer-coated panels and membranes. Novel panel components are pre-fabricated to provide a rapid installation, yet one which can achieve a high integrity, and a high aesthetic quality.

The cost and weight of materials can be reduced, compared with the design of GB 2448148 A, for example.

The invention in a first aspect provides a method of installing a building skin on supporting structure, the method comprising: -providing a set of prefabricated panels, each panel comprising a flexible membrane reinforced along at least one edge by being bonded to a strip of relatively rigid material; -fitting a first one of said panels to said supporting structure to form a first unit area of the skin; -fitting a second one of said panels to said supporting structure to form a second unit area of the skin adjacent the first unit area, fixing said rigid material to the supporting structure, so that said reinforced edge of the second panel overlies an edge of the membrane of the first panel which is opposite the reinforced edge of the first panel; -fitting further panels in the manner of the second panel so as to extend the skin area.

The panel membrane may be of polymer material, for example PIB or PVC, while the rigid strip is metal such as steel. The rigid strip provides the fixing points for the panel without requiring the entire panel to have the weight or cost of the panels described in GB 2448148 A, mentioned above. The strip can be shaped to provide architectural details to improve the aesthetic qualities of the installation, for example to mimic traditional lead roof details.

The rigid strip of a panel is preferably fixed to the structure without piercing the membrane of the same panel, to achieve a high integrity as well as a clean appearance.

In a preferred embodiment, the rigid material is only partially bonded to the flexible membrane, an unbonded portion of the rigid material is exposed through which the strip is fixed to the supporting structure, and then the membrane is flattened over the fixed strip to cover the strip and an area of the structure The panels may also be fixed through the unbonded portion of the rigid strip to a supporting structure and a previously laid panel, depending on the distance of overlap between two panels along the same longitudinal axis. In a preferred embodiment of installation, the panels over lap each other such that the rigid material is fixed through a previously laid panel and to a supporting structure.

Each prefabricated panel may further comprise a lapping strip of flexible membrane material sealed to and projecting beyond the reinforced edge of the panel, the method further comprising the step of bonding said lapping strip to the material of the underlying so as to form a sealed joint between the panels.

The bonding may be by heat welding polymer said membrane materials, though of could adhesive sealants and the like are not excluded. Another option is to provide a low molecular weight coating or layer of similar material, which will fuse over time to create the seal.

The reinforcing rigid material may be a metal such as steel, coated with a polymer layer, the polymer layer then being heat welded to the larger membrane.

Where the structure is vertical or inclined, it is advantageous for integrity against water ingress if the second panel is be mounted higher than the first panel, and further panels to extend upwards.

The first, second and further unit areas may form a first run of panels, the method further comprising a step of laying further runs adjacent to the first run, with edges of the further run of panels overlying the edges of the first run. It is not necessary for one run to be completed before the next run is started, provided the installation sequence respects the need for any individual panel to be laid before the panels which overlie it above or to one side.

The edges of the panels in the first run may be fixed to the supporting structure prior to addition of the adjacent panels in the second run, the overlying portion of the second run panel then covering the fixing points.

The rigid strip may be arranged asymmetrically with respect to the overall width of the membrane panels, to facilitate overlapping of their edges and concealed fixing.

A capping strip may be mounted on the longitudinal seam.

The positions of panels within runs may be staggered from one run to the next, some runs starting with a shorter panel.

The invention in the first aspect also provides a prefabricated panel assembly for use in assembling a building skin, the panel comprising a flexible membrane having a weather surface and a rear surface, the membrane rear surface being bonded along at least one edge to a strip of relatively rigid material, the rigid material further having an unbonded portion, whereby in assembling said building skin said unbonded portion can be exposed temporarily to allow fixing the strip onto a supporting structure, the unbonded portion then being re-covered by the membrane in the finished assembly.

In a preferred embodiment, the panel further comprises a lapping strip of flexible membrane material sealed to and projecting beyond the bonded edge of the panel.

The length of the reinforcing rigid material along the bonded edge may be less than the whole width of the flexible membrane.

The rigid strip may comprise a wing in the unbonded portion, which extends beyond the length of the rigid strip along the bonded edge, the rigid strip being still within the whole width of the flexible membrane.

The rigid strip may further comprise a hemmed portion formed by curving a portion of the rigid strip, and wherein the hemmed portion is bonded to one end of the membrane edge with the whole width of the flexible membrane substantially folded over the hemmed portion.

The lapping strip may be bonded to the whole width of the flexible membrane folded over the curved hemmed portion of the rigid strip.

The flexible membrane folded over the curved hemmed portion may comprise a chamfer near the membrane edges, so that the lapping strip may be bonded, over the chamfered area, to a single layer of the flexible membrane.

The rigid strip may also comprise a joggle bend portion formed by creating a step along the piece of rigid strip. The step may be formed along the rigid strip further beyond the formed hemmed portion, and the step may be formed in a direction to compensate for the thickness created by the hemmed portion.

The hem and joggle shape of the panel assembly advantageously mimic the more common traditional lead sheets roof after installation.

The area of the rigid strip away from the membrane edge, beyond the joggle step, may comprise the free unbonded portion.

The panel may comprise further fixings for the edges of the flexible membrane, to fix the panel to a supporting structure and may also include a previously laid panel.

Depending on the distance of overlap of panel in a run (i.e. panels that are installed along the same longitudinal axis, such as from the eaves to the ridge), the fixings may not necessarily be fixed solely to a supporting structure.

The bonding may be by heat welding. The strip of rigid material may be a metal such as steel, coated with a polymer layer, the polymer layer then being heat welded to the larger membrane. The rigid strip may be arranged asymmetrically with respect to the overall width of the membrane panels. The structure may be vertical or inclined.

The invention in the first aspect further provides a building skin fitted with a plurality of panels as set forth above and/or installed according to a method as set forth above.

The building skin may comprise a plurality of panels aligned along the same longitudinal axis from the eaves to the ridge and overlapping each other to form a first run and may further comprise a plurality of runs also overlapping each other laterally. The plurality of panel runs may be installed staggered to each other to create a broken bond effect.

The invention in this first aspect provides a kit comprising a plurality of prefabricated panels.

according to the invention as set forth above kit may further comprise fixings to fix the panel assembly to a previously laid panel assembly and a structure.

The panels may be rolled and stacked or stacked flat for transportation to an installation or stocking site.

The invention in the first aspect further provides a method of producing a panel assembly for use to form a building skin comprising: providing a flexible membrane of sufficient size to form said panel; bonding a strip of relatively rigid material to one edge of the flexible membrane, leaving unbonded a portion back from the membrane edge, so that said portion may be used for hidden fixing.

The method may further comprise: leaving the edge bonded to the strip of rigid material unrolled, to form a rolled-up panel assembly; and/or forming the strip of rigid material, of the fixed panel assembly, into a three-dimensional shape.

The rolled flexible membrane may be fixed in its rolled state to aid handling in position by tack welding, for example one of the edges of the flexible membrane.

Preferably, the edge that will be overlapped during installation of the panel to form a building skin is tack welded.

The shape formed may be a hem and joggle portion as set forth above.

In a second independent aspect, the invention provides a method of attaching accessories to a building skin, comprising: providing a prefabricated attachment comprising a first strip of flexible material having a first and second end, the first strip arranged on top of a second strip of flexible material having a first and second end, wherein the strips are bonded to one another over a central area while leaving all ends of the strips unbonded; bonding at least part of the second strip of the attachment onto the building skin; folding the ends of the first strip over an accessory and bonding them to the accessory and/or one another, thereby to mount the component on the skin; The accessory may have first and second parts (for example a main part and a cover part), the methods comprising: leaving the ends of the second strip unbonded to the building skin; attaching the first accessory part arranging the first accessory part on top of the bonded attachment and folding and bonding by the ends of the first strip at least partially over the first accessory part; attaching the second accessory part by arranging the second accessory over the attached first accessory and further comprising folding the first and second ends of the second strip at least partially over the second accessory to be bonded thereto.

Bonding the attachment to the building skin may be by bonding an area underneath the second strip to the building skin. The area of the bonded attachment underneath the second skin may be the same and directly underneath the area over which the first and second strip are bonded.

Bonding may be by heat welding, by adhesive or by use of self-welding material.

The strips and the building skin may be of the same polymer material (possibly with different molecular weights).

The area of the bonded strip may be at the centre of the first strip and offset by a distance from the centre of the second strip.

The length of the first strip may be longer than the length of the second strip. The edges of the second strip may be rounded.

The accessories may be accessories adding architectural detail to a membrane building skin, without penetrating and comprising its integrity. The first accessory part may be a bottle cap strip to simulate lead roofing and the second accessory may be a knuckle used to cover the bottle cap at the join of two bottle caps strips.

In the second aspect, the invention also provides a prefabricated attachment, for use on a building skin or other surface, comprising a first strip of flexible material having a first and second end, the first strip arranged on top of a second strip of flexible material having a first and second end, wherein the first and second strips are bonded together over a predetermined area leaving all ends of the strips unbonded.

In a third independent aspect, the invention provides a method of attaching a first component to a building skin comprising: providing an attachment device with a base and upper part fabricated with a layer of flexible material bonded to the base of the attachment and extending beyond said attachment base; arranging the base of the attachment with the bonded flexible material on top of the building skin bonding the layer of flexible material to the building skin; attaching the accessory by fixing the accessory to the upper part of said attachment.

A second accessory may be attached to cover the attachment, for example by sliding the second component in position over the first fixed component.

The attachment may comprise atop hat structure of folded metal, or a plastic or metal moulding. The top hat structure may be inverted.

The method may further comprise fixing the base of the attachment of the building skin by a penetrating fixing, wherein said bonding between the layers of flexible material to the building skin creates a seal around said penetrating fixing. Versions welded without penetrating the membrane are obviously attractive from the integrity point of view, while a penetrating fixing might be required for load-bearing accessories.

The upper part may be movable between: a first configuration wherein the base exposed from above be accessed to fix the attachment to the building skin; and, a second configuration in which the base is covered and adapted for receiving the accessory.

The penetrating fixing used for fixing the base of the attachment to the building skin may comprise a waterproof seal where it penetrates the base part from above.

In the third aspect, the invention also provides an attachment for use on a building skin, comprising: base and upper portions; a layer of flexible material bonded to the base portion and extending beyond the base portion for bonding to a supporting surface; Optional features of the attachment are as set forth for the method above.

These and other aspects of the invention will be understood from a consideration of the detailed examples described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, by reference to the accompanying drawings, in which: Figure 1A shows a section of a roof with seven panel assemblies according to an embodiment of the invention installed; Figure 1 B is a cross section down the line B-B' as shown in Figure 1A; Figure 2A shows the top side of a panel membrane that is used to form a panel assembly according to one embodiment of the invention; Figure 2B shows the under side of a panel membrane attached to a metal piece to form a panel assembly according to one embodiment of the invention; Figure 3 shows a panel assembly partially rolled up before being sent to a factory for fabrication according to one embodiment of the invention; Figure 4 shows a panel assembly with a joggle, hem and lap strip according to one embodiment of the invention; Figure 5A shows a transportation pallet carrying assemblies in a rolled up configuration; Figure SB shows a transportation panel used to transport panel assemblies that are in a flat position, to the building site; Figure 6 is a cross sectional detail of an eaves type panel assembly bottom edge; Figures 7A and 7B show in detail the overlapping of two panel assemblies in different runs during installation of a building skin; Figure 70 shows a modified detail, where a portion of the panel membrane is chamfered and a cut-back (shorter) lap strip is used; Figure 7D shows a further modified detail, wherein an outer edge of the panel membrane is laid flat for sealing with a previously laid panel, rather than hemmed; Figure 8 shows in more detail a fixing screw according to one embodiment of the invention; Figure 9A shows the strip-like components of an attachment for a bottle capping or other accessory; Figure 9B shows the strips of Figure 9Awelded together to provide the prefabricated attachment; Figure 10 shows in cut away form a bottle capping and the attachment arranged over a section of the panel assembly; Figure 11 shows the bottle capping and the attachment arranged over a section of the panel assembly in a perspective view; Figure 12 in the cross section shows the bottle capping being attached; Figure 13 shows the bottle capping being attached, in a perspective view; Figure 14 shows in cross section the knuckle arranged over the bottle capping and being attached; Figure 15 shows the knuckle arranged over the bottle capping and being attached, in a perspective view; Figure 16 shows the finished building skin over an extended area, with capping strip; Figure 17A shows a second attachment which may be used to attach accessories such as a capping strip and a knuckle to a building skin; Figure 17B is a top view of the attachment of Figure 1 7A; Figure 18 shows in cross section the attachment of Figure 17 A, 1 7B with a capping strip and knuckle attached; Figure 19A shows a third attachment which may be used to attach accessories such as a capping strip and a knuckle to a building skin; Figure 1 9B is a top view of the attachment of Figure 1 9A; Figure 20 shows the second embodiment of the second attachment in position on the installed panel membranes, which forms the building skin, for fixing the capping strip and knuckle; and Figure 21 is a cross-section on line C-C' of Figure 20 with the capping strip and knuckle.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Installation Overview Figures 1A and lB show a portion of a roof covered with panels to form a roof skin for a building. The construction can equally be applied to a vertical or sloping wall, and the example of a roof will be used for simplicity. Figure 1A only shows seven panels, namely 101, 102, 103, 104, 105, 106 and 108. Figure lB shows the side view of the run of panels 101, 102 and 103 overlapping each other as shown in Figure 1A. The gable side is shown by 132 and the eaves (gutter) of the roof is found at 134.

The ridge or top of the roof is found in the direction of the arrow 136. A first run of panels is formed by panel assemblies 101, 102, 103 and all panel assemblies on the same longitudinal axis up to the ridge of the roof. A second run of panel is formed by panel assemblies 104, 105, 106 and all panel assemblies on the same longitudinal axis up to the ridge of the roof. Similarly, a third run of panels is formed by all panels on the same longitudinal axis starting with panel 108.

Every panel assembly includes a relatively rigid metal piece 140 or 142 incorporated at its bottom edge. Figure 1A shows panel membranes 108, 104 and 101, adjacent to the eaves, having an eaves type of metal piece 140. Figure 1A also shows the rest of the panel membranes 102, 103, 105 and 106 welded to metal pieces 142.

Fixings 170 are fixed through a part of each metal piece 142 or 140 of each panel assembly to the roof structure. These fixings are hidden and covered by the membrane of the panel, however. Due to the overlapping of the panel assemblies in the same set, each fixing 170 also goes through a portion of a previously laid panel membrane, as shown in Figure 1 B. Therefore, fixing the metal piece of panel 102 to the roof structure also, purposely, fixes panel membrane 101 to the roof structure. However, this is optional as the panel 102 may be fixed directly to the roof structure in another embodiment, depending on the distance of overlap.

For describing each panel membrane we shall say that it has four edges 180, 182, 216 and 218, as labelled on the example of panel 106. Side edge 180 will be described as the leading side edge, whereas side edge 182 will be described as the trailing side edge. Edge 216 will be described as the bottom edge (referring to its position in the installed panel when on a pitched roof) and edge 218 will be described as the top edge. A trailing edge is the edge of the panel membrane in the panel assembly that will consequently be overlapped by the leading panel assembly of an adjacent run in the skin installation.

Every metal piece is shaped to have a hemmed portion 260 and joggled portion 262, for example, as shown by the metal piece 142 of panel 106. Figure lB also shows the side view of the metal pieces 142 of panel assembly 102 and 103 of Figure 1A with the joggle 262 and hemmed 260. As a result, each panel membrane also has the shape of the hemmed and joggled portion, being bonded closely to its respective metal piece 140 or 142. The shape in question is designed partly for cosmetic effect, mimicking a traditional folded joint between sheets of lead in a lead roof.

Figure 1A also shows fixings 122 which are be used in addition, to fix the leading side edge 180 each panel membrane to the roof structure. The side edge 180 is also the edge which will be overlapped by the trailing side edges of the adjacent run. As will be described in more detail later, these panels of the adjacent run will cover the fixings completely.

All the panel assemblies adjacent to the gable 132 of the roof have additional fixings 120 along the edge 182 at the gable. As shown in Figure 1A the gable panels 101, 102 and 103 are all fixed using fixings 120 along edge 182 and are also fixed, like every other panel assembly on the roof, using fixings 122 on the unbiased edge 180. The form and fixing of the panels at special features such as eaves, gables and ridges are considerations separate from the basic concept of the skin construction over its main area.

Fabrication of Panel assembly Figure 2A shows the top side T of a panel membrane 210 that may be used to form any individual panel assembly of Figure 1A. Figure 2A shows the panel membrane without a piece of metal 140 or 142 welded to it. The panel membrane is preferably made of Rhepanol�, Rhenofol�, or generic polyisobutylene (PIB), polyvinylchloride (PVC) material or any polymer membrane that is weatherproof and flexible, preferably weldable by heat. The inclusion of a fabric or other fibres or particles in the material is of course not excluded. In one embodiment, the panel membrane is cut to a size of 3000 mm in length and 683 mm in width Figure 2B shows the underside U of a panel membrane 210 with a metal piece 212 welded to it to form a panel assembly according to the embodiment of Figure 1. The metal may be steel, pre-coated with compatible polymer and sealed to the edge 216 of the membrane without the use of separate adhesives by application of heat from a hot air gun. As shown in Figure 2B, only a portion 256 (hatched) of the metal 212 is to be heat welded to the edge 216 of the panel membrane 210, leaving a free end portion 254.

The metal piece 212 of the panel assembly of Figure 2B is applied flat, but marked on the drawing with lines for a hem 260 and a joggle 262. The fabrication of these features will be described shortly with the help of Figure 3 and 4. The joggle and hem is preferably formed within the portion 256 which is welded to the panel membrane 210.

In this example, the metal piece 212 is asymmetrical, and has a wing 220 that is formed to provide a suitable base for fixing, as will be explained in more detail later.

The wing 220 is located near the leading edge 180 of the finished panel rather than trailing edge 182. The wing is formed at the free end portion 254, rather than the bonded portion 256.

The metal 212 is welded at the edge 216, biased towards the leading edge 180 with the length 250 greater than the length 252. The biasing feature assists overlapping by providing a clearance for panel assemblies of adjacent runs to overlap over previously laid panels, without creating unnecessary thickness.

In this embodiment, the metal 212 is cut down to the size of 513 mm by 200 mm and welded such that 250 is 110 mm and 252 is 60 mm. The welded area 256 is, say, 80 mm by 513 mm. The wing 220 projects towards the edge 180 by 50mm and covers a length of 120mm along the longitudinal axis. In this embodiment, the free portion 254 (including the wing) therefore has a dimension of 563 mm by 120 mm.

The metal when coated with a layer of PIB provides a barrier to corrosion of the metal, in addition of providing an aesthetically pleasing finish. In one embodiment, the metal is laminated in the same polymer as the panel membrane, which facilitates manufacture by heat welding. Compared with the construction of the inventor's earlier application, mentioned above, the amount of coated metal used is greatly reduced.

Figure 3 shows the panel assembly of 2B rolled up, leaving a loose portion of the membrane unrolled near the edge with the metal piece 212. A tack weld 310 is made to hold the roll in place while fabricating the hem and joggle. The rolled up panel assembly is convenient for transportation around the factory and, in one embodiment, is maintained for transportation to the site.

The panel assembly is preferably rolled with the top side T on the inside of the roll putting the weather surface on the inside. The tack weld is preferably formed on the leading edge 180, that will eventually be overlapped and hidden by adjacent panel assembly in an adjacent run, that is edge 180 as shown by Figure 3.

Figure 4 shows the completed panel assembly, now labelled 410. with metal piece 212 joggled and hemmed. Figure 4 shows the panel assembly ready for transportation to the site, with a portion of the panel membrane rolled-up and after the hem 260/322 and joggle 262 have been formed. 322 indicates the hem made by folding and pressing the metal back to the line 260. When the metal piece 212 is folded to form the hem and joggle portion, the flexible membrane therefore also follows the fold. Recall that the free end portion 254 of the metal piece is not welded to the panel membrane 210, though they lie flat together.

The panel assembly in this embodiment also includes a lap strip 324 welded to the membrane over the hemmed portion of the panel assembly. Preferably, the lap strip is made of the same material as the panel membrane, or at least a polymer or material that can be heat welded to the panel membrane and is flexible to form a seal with other panel membranes. In the present example, this is a separately cut strip of material, though potentially it could be made by an extension of the main membrane 210, folded and welded back on itself under the hem.

In our example, the hemmed portion 342 is 30 mm and the joggle portion 340 is 50 mm. The lap strip 324 is formed along the whole width of the panel membrane 210, beyond the width of the formed laminated metal, as shown in Figure 1A, panel 103.

In this embodiment, the lap strips 324 have a dimension of 683 mm by 50 mm. All the dimensions given are of course approximate, and for illustration only.

One of the advantages of the jogged portion is to correct for the thickness created by the portion of the metal that has been turned around to form the hem. In this embodiment of the invention, where a lap strip 324 is provided, the joggle portion corrects for the thickness formed by the hem and the lapping strip. The joggle thus enables overlapping of panels in such a way that reduces undesired stretching forces of the panel membranes. Stretching forces may arise when trying to position overlapping flexible panel membrane of the same or different sets levelled to the roof surface As below, and shown in the embodiment of Fig 70, the lapping strip may not run along the whole width of the panel membrane. By cutting short the lapping strip 324 at the edges, and chamfering the membrane hem, then a good flat surface and weld is achieved.

Another advantage of forming the hem and joggle portion, as mentioned above, is to mimic the appearance of the more traditional lead roofs that are widely in use.

Figure 4 also shows the panel rolled-up (for transportation to the site) in the opposite direction as in Figure 3 (before forming the hem, joggle and fixing the lap strip). There is no preference on which direction or manner the shaped or pre-shaped panel assemblies should be rolled-up as long as they are rolled up to assist and ease the job of the handler for fabrication, transportation and installation on site. This may vary with details of the construction or working method.

Figure 5A show a plurality of panel assemblies 410, in a rolled-up position, on a transportation pallet 510 before transportation to the installation site. A cover 512, made with a flexible material, is preferably used to keep all the panel assemblies in place on the pallet. Where the pallet 510 is made of wooden slats, care should be taken to avoid the edges digging into and deforming the membrane material.

Figure SB shows a flat stacking method for carrying the panel assemblies to the installation site. The sheets rolled according to Figure 5A will tend to adopt a curled or even wrinkled form when laid flat on the roof. Even if this deformation disappears over time, it makes it harder to achieve a good fit of the skin to the supporting structure. The flat stack on pallet 520 avoids this. The base of the stack is fully supported on sheet metal 522 to avoid "troughing" in the pile due to weight and the slatted construction of the wooden pallet 520. A further flat metal sheet 524 is provided on top. The material should be shrink wrapped to ensure the cleanliness of the laps, although the material is easily cleaned with thinners provided by the supplier.

Installation on site Having prefabricated sufficient panels of the eaves type and general type, these are delivered to site as described and fitted by the following method to form the roof shown in Figure 1A and lB. As it will be explained later, the first (eaves) panel of each run requires a slightly different profile (Figure 6A) from the rest of the panels in the run, however uses the same method of fixing. Separate stacks may be provided for the eaves type panels 101, 104, 108.

After preparation of the flat supporting structure with its framework, insulation/vapour barriers and the like, the first panel assembly 101 is laid at the corner of the eaves 134 and gable 132 of the roof. More panels 102, 103 etc. are laid, along the same longitudinal axis parallel to the gable, ending to the ridge, to form a first run of panels. It is understood that the first panel or run of panels to be laid will normally be started either on the left or the right gable of a roof or wall to be skinned. If the panel assemblies are symmetrical this may be a free choice for the installer. In the preferred embodiment, the side to start is dictated by the asymmetrical form and positioning of the metal pieces 212 on the membrane.

Thus, in this example, the first run of panel is with the leading edge 180 away from the gable and the first panel trailing edge 182 at the gable, with the metal piece welded biased towards edge 182 (as shown in Figure 2B).

Panel assemblies in each run overlap each other (such as panel assemblies 101 and 102, or 102 and 103). With proper joining technique, as described further below, this creates a skin of high integrity and prevents water ingress. In this embodiment, the panel assemblies overlap each other substantially over the length of the metal piece 212 welded to them.

The second run of panel assemblies is then laid, adjacent to the first run, with the first panel assembly of the second run starting again at the eaves. The panel assemblies of the second run are positioned "staggered" with the first run by starting with half a sheet of a panel assembly, as shown in Figure 1A.

Consequently, the first panel of the second run will follow the same pattern, for example, the first panel of the third run is a full sized one, and the first panel of the fourth run, is again half-sized. For the purposes of the following explanation, it will be assumed that each run is completed before the next runs is started, though Figure 1A itself illustrates that this need not be the case.

The adjacent runs of panels overlap each other, again for integrity and to hide their fixings. Specifically, the trailing edges 182 of the second run of panels overlap the leading edges 180 of the first run. In this embodiment, the panel assemblies overlap each other over the distance 250. In this configuration, the panel assemblies overlap such that the membrane edge 182 of panel assembly 106, say, of the second run flushes with the edge of the joggle portion 262 in the metal piece 212 underlying panel 103. The wing 220 of panel 103 is therefore completely covered and so are fixings 122 which hold leading edge of panel assembly 103 to the supporting structure.

Figure 6 shows in cross-section a panel assembly being fixed to the roof structure at the eaves. The metal piece 140 of this eaves-type panel is shaped with a drip profile (inverted L shape) as shown in Figure lB and 6. This is slightly different from the metal pieces 142 of all the rest of the panels to be installed (shown in Figure 1 B and 4).

On site, during installation, the alignment of the laying pattern is established at the time of installation, by laying the panel flat at 90 degrees from the eaves with the top or weather surface exposed to the outside. In this embodiment the panels are aligned parallel to the gable. Once aligned, the flexible membrane is then rolled back starting from the edge 218 or simply lifted from edge 218, in order to gain access to the free end portion 254 of the metal piece 140. A fixing 170 is then placed through the free exposed portion 254 of the metal piece 140 to fix the panel assembly to the roof structure.

Figure 1 B shows how the fixing 170 of a panel assembly which is not at the eaves, such as panel assembly 103, also goes through the overlapping portion of the panel membrane of the previous panel assembly 102, near its top edge 2187. Otherwise, the same method of fixing is also used for all the rest of the panel assemblies 102, 103 etc. on the roof that do not have a drip profile.

The fixings 170 use washers and screws in the normal way. In this embodiment, the fixings 170 of the metal pieces are fixed no less than 10 mm from the edge 218 of the previous panel to be overlapped. In the case of the eaves panel, there is no previous panel to be overlapped and therefore the fixings 170 go directly through the roof structure.

A strengthening anchor 430 may also be fixed to the eaves or roof structure before installation of an eaves panel. This is particularly useful in the event that the eaves is shaped such that a good grip cannot be obtained.

After fixing through the metal strip, the membrane is rolled back into position and the leading side edge 180 of the panel is fixed with fixings 122 along its edge.

Fixings 120 are only required by panels that are adjacent to the gable and may also be fixed at this time. The fixings 122 and/or 120 are screws that are fixed through the panel membrane no more than 50 mm from the edges 180 and 182 respectively.

Figure 7A shows the fixings 120 and/or 122 comprising a countersunk large oval washer 702 and a screw 704. Because of the countersinking, the screw head does not protrude into the membrane above. Typically, the fixings 122 or 120 are placed 300 mm apart along the edges of the membrane.

The next panel is laid over the eaves panel or a previous panel and the setting is established by ensuring that the overlapped edge 218 of the previous panel is flush with the top edge 350, as shown in Figure 4, of the exposed flange portion 254.

The panel is rolled out flat to establish the correct line then rolled back and fixed, using fixings 170, through the exposed portion 254 to the roof structure and the top of the previous panel. The lapping strip 324 of the panel is then welded over the full width of the previous panel. All of the proceeding panel assemblies are laid in this fashion up to the ridge line. The situation shown in Figure 1 B results.

Once a first run of panel assemblies is installed entirely up to the ridge, installation of a second run of panels is started adjacent to the first run of panels. Trailing edges of the second run of panels overlap the leading edges of the first run of panels, to cover amply the fixings 122 of the first run of panels. Beyond the line of the fixings 122, a welded sealed join is made between the membranes, so that the parts pierced by fixings 122, as well as fixings 170, are completely sealed from the environment. A plurality of runs are installed next to each other to form a roof skin, until the roof surface is completely covered and protected.

Figure 7B shows a closer view of two panels overlapping each other in adjacent runs. The metal piece 212 is shown in dotted lines with the hem and jog formed.

The flexible membrane 210 of the panel assembly follows the shape of the metal piece. The lap strip 324 also covers the whole width of the flexible membrane. The lap strip is heat welded to the membrane below, which in this example is already pinned and trapped beneath the metal piece 212 and fixing 170.

Figure 70 shows another embodiment, in which the hemmed portion of the panel membrane 210, already welded over the hem portion 260/326 of the metal piece of the panel assembly, is provided with a chamfer 710 and a shorter lapping strip 324 is also used. As shown, the lapping strip 324 is stopped short of the edge, but may still extend beyond the width of the metal piece 212, to ensure the section 712 of the main membrane sheet to be welded directly to the previously laid panel. A better seal is ensured because only two layers have to be heat welded together instead of four, i.e. the panel membrane 210 is heat welded directly with the membrane of a previously laid panel 720 over the chamfered area (not comprising the lapping strip) instead of the lap strip, two full layers of panel membrane (includes the membrane hem) and the membrane of a previously laid panel.

Figure 7D shows a further variation, where the outer portion 730 of the membrane beyond the chamfer not hemmed but laid flat. This allows panel membrane 210 and portion 730 to be folded flat and sealed to a previously installed panel membrane 720, thus avoiding potential capillary passages for water ingress.

As mentioned previously, by cutting short the lapping strip 324 and chamfering the membrane hem, then a reasonably good flat surface and weld is achieved. The variations such as short lapping strip and chamfer can be used together or independently, to suit the material and integrity requirements.

Other embodiments & variations In another embodiment, the metal piece 140 or 142 does not have a wing 220. In this case a rectangular metal piece 212, preferably with dimensions 513 mm by 200 mm, is partially welded to the panel membrane.

In another embodiment, the metal piece is not welded at the rim of the edge 216 of the panel membrane 210. The metal piece 212 is instead welded a few millimetres back from the edge 216 of the panel membrane. In one example, mentioned already above, the membrane extends far enough beyond the edge of the metal piece to be folded back on itself and form the lap strip 324.

In another embodiment, only part of the joggle 262 is welded to the panel membrane, i.e. the panel membrane can be rolled-up or lifted over the joggle 262, up to a point along 340 (shown in Figure 4) where the panel membrane is welded to the metal piece 212. This may facilitate better access for fixing, in cases where the metal strip is quite narrow, and/or the membrane material is relatively stiff.

The panel assemblies in the same run may overlap with each other over more than the length of the metal piece 212 along the longitudinal axis. In another embodiment, the panel assemblies in the same run overlap with each other over less than the length of the metal piece 212, along the longitudinal axis. Preferably they still overlaps by enough so that fixings 170 can be fixed through the free end 254 of the metal piece 212, the panel membrane 210 of the previously laid panel assembly and the roof structure. In another embodiment, the panel assemblies in the same run overlap with each other over less than the length of the metal piece 212 along the longitudinal axis and a fixing 170 is fixed through the free end of the metal piece 212 to fix the panel assembly directly to the roof structure. In that case, the top edge of the lower panel membrane is held merely by being under the hem portion of the metal strip above it, and welded to the material of the upper panel (in particular the lapping strip 324, where provided).

The length of the first panel assembly of every second run need not be exactly half that of a normal panel assembly, depending on the type of broken bond' desired. A staggered pattern may not even be desired. The shorter panels may be purposely prefabricated and transported to the site or may be fabricated on site. For example, on site, a shorter panel may be made by simply cutting a full sized panel to the desired length. Alternatively, panels of different runs may be aligned.

The fixings 170 and/or 122 can be provided by nails, staples or other means besides screws. The fixings to be used will vary according to the structure of the substrate and the expected loading under different temperature and wind conditions.

In another embodiment of the invention, there may be a gap left between the edge 182 of panel 106 and the nearest edge of the joggle of panel 103 however, still covering fixings 122. In another embodiment, the metal pieces 140 of panel 101 and 104 being substantially levelled with each other with no gap 150 between them.

In another embodiment of the invention, fixings 120 also fix a rail for supporting a side verge cover over the gable.

In another embodiment, the first panel assembly of each array is shaped, on site or prefabricated, according to the eaves shape to provide maximum gripping force and strength.

Accessories -Capping Strips and Knuckles The method described above provides a complete weathertight skin. However, its appearance, particularly along the longitudinal seams, will be somewhat bland in appearance. We now describe how the panels are finished by installing a bottle cap' capping strip along the longitudinal joint formed by adjacent overlapping runs, from the eaves to the ridge. Knuckles are also installed over the bottle cap at predetermined distances. The overall installation gives an aesthetic finish, again mimicking the appearance of a lead sheet roof, without compromising its high integrity. Two novel methods are presented to fix the bottle cap and knuckles to the installed panels. The first one described uses a double strip of flexible membrane and does not require using any screws or piercing the panels in any way. The second method described uses an inverted top hat bracket and a screw, with special measures to maintain integrity.

It is assumed that the capping strip is made by folded metal coated with the compatible polymer layer, such as PIB. An alternative method is to use the extruded polymer bottle capping and knuckle joints as described in GB 2448148 A. The relevant content of that application is incorporated herein by reference.

Fig 8 shows the transverse cross-section of an elongate bottle cap' strip 812. In the preferred embodiment, the capping strip is laid straight from eaves to ridge.

Forming longer runs can be assisted with the use of an internal butt-strap at the joints. Short knuckle pieces 810 are provided at intervals. These may be especially at the joints between lengths of strip 812, but can be provided for aesthetic effect at any point along the bottle caps. The bottle cap and knuckles have a raised profile and contribute aesthetically by mimicking the traditional rolled seams of a lead roof.

Therefore, a knuckle is provided wherever a transverse seam with joggle terminates. In general, addition or withdrawal of accessories such as these capping strips and knuckles is dependent on the aesthetic look of the roof that needs to be achieved. The joins that are used to fix the bottle cap and knuckle to the roof skin have no bearing on the functionality of the roof skin already laid. Other types of accessory that may be decorative or have a function can also be attached using the methods described.

Accessory Fixinci -First Method Fig 9A shows an attachment used in the first novel method to secure the bottle capping and knuckle to the panels. The attachment is made by using two pieces of flexible membrane as shaped in Fig 9A. In this embodiment, the pieces 914 and 912 are preferably cut out of the same membrane as the flexible membrane used for the panels. Strips 914 and 912 in this example have a width 918 of 50 mm. The lengths of the strip pieces may not be the same. The strip 914 is placed on top of strip 912 and is offset by a distance 920 on one side before being welded together over the hatched area 910 to form a single component with four free ends. The other side of strip 914 is also offset by a smaller distance. The length of the area 910 is 60 mm. Fig 9B shows the double strips after being welded together. The ends of one or both strips may be rounded as shown, to achieve a better aesthetic look, in the finished installation.

Figures 10 and 11 show the double strip 914 and 912 welded together and positioned for fixing capping strip 812 over the seam in a roof skin made as described above. The double strips, in this embodiment, are located at the joint of the preformed laminated bottle capping and at the midway point which should correspond with the "panel" intersection of a staggered pattern. As shown in Fig 10, the bottle cap and double strip may be located centred between the edge of the metal strip 1014 of the panel assembly and the overlapping edge 1020 of the panels. The bottom of the double strip is heat welded at 1010, preferably over an area between 50mm and 80 mm, to the field sheets or panel membranes. This is shown on a membrane sheet with chamfered hemmed portion and lap strip mentioned above in connection with Figure 70. The bottom strip is welded by an extended area 1200 over the side which comprises the metal strip/former of the panels. As seen in Fig 10, one side of the bottle capping flushes with the edge 182 of the panel membranes in the overlapping run. This is a matter of detailed design choice, however.

In Figures 12 and 13 the bottle capping has been laid over the membrane strips and held down in position. The wings of the top strip 914 that are unbonded are stretched and heat welded over the capping strip.

In Fig 14, the knuckle piece 810 is placed over the capping strip at the same location. One wing of the bottom membrane strip 912 is welded to the building skin/panel membrane, preferably between 20 mm and 25 mm, along the raised overlap of the field material (as shown in Fig 10 and 12 by 1200) or panel membrane and returned on itself. The shaped tongue 1400 is welded to the side of the knuckle, lapping up the side of the held down knuckle piece. The other wing of the strip 912 is simply stretched and directly heat welded to the knuckle piece to also form a lip. This helps to reinforce the end of the membrane formerly covered, and additionally creates a larger area of "holding down" for the bottle capping. One of the fixings 122 or 170 is indicated at 916.

Fig 15 shows a first side view of the capping strip and knuckle after fixing. Fig 16 shows a perspective view of a capping strip 1614 and two knuckles 1610 and 1612.

The tongues of strip material are formed on alternate sides of the bottle capping to accommodate for the raised profile, according to the panels as already installed (staggered pattern). These tongues replicate the tingle' feature of a traditional roof.

The distance by which the strips are offset and the area over which they are welded to form the double strip may depend on the pattern of the panels in the roof skins.

For example, in case of fixing the attachment to panels which are aligned to each other (as opposed to being staggered), a longer length of the double strip may be required two form a shaped tongue 1400 on each side of the bottle cap to accommodate for the raised profile of metal strip/former on each side.

Note that the novel fixing method involves no special materials and no piecing of the skin just made. Batches of double strip attachment 912/914 can be pre-formed for a consistent performance.

Accessory Fixinci -Second Method Figures 17A and 17B show an attachment used in the second method of fixing capping strips and knuckles to the roof skin. An inverted top hat' section of laminated metal 1700 has a square of membrane 1714 welded to its underside.

Preferably, the metal is laminated using a polymer coat, such as PIB. Again, batches of these attachments, including welded membrane, can be prefabricated off site and delivered for ready use. The inverted top hat laminated metal also comprises of two pierced wings 1712 and 1716 which can be folded inside the top hat.

Figure 18 shows schematically the inverted top hat in use to fix a capping strip 1850 and a knuckle 1852. First, the inverted top hat is positioned laterally and fixed through the centre with a neoprene washer 1856 and screw 1854. In the roof example above, its position is preferably dead centre between the metal strips, preferably 35mm, which will afford ample welding area below the knuckle position.

In this embodiment, the inverted top hat attachment is preferably fixed through the unbonded wing portion 220 of the metal strips of the panels in the building skin (as described above), which provides a suitable base to hold the attachment.

The square of membrane 1714 is then heat welded to the installed panel membranes. The wings 1712 and 1716 of the inverted top hat attachment are folded inward and the pre-formed capping strip laid over the top hat seat and the capping strip 1850 is fixed to the top wings of the units, preferably with small self-drilling screws or rivets 1858. The end joints of the capping strips fixed to both wings and butted. Finally, the knuckle pieces 1852, which have in advance been fitted over the capping strip at a distance from the fixing point are slid over the joints at the ends and mid-way. As before, the knuckle position and attachment locations along the longitudinal seam can be chosen according to the aesthetic look that needs to be achieved.

In a further embodiment, as shown in Figures 19a and 19b, the attachment comprises of a "non-inverted" top hat structure 1912 which is heat welded to a piece of flexible membrane 1910 material over the wing areas 1914 of the top hat.

As previously described, preferably, the structure is metal laminated using a polymer coat, such as PIB. Batches of these attachments, including welded membrane, can be prefabricated, and quality controlled off site and delivered for ready use.

Figures 20 and 21 show schematically the top hat attachment in use to fix the capping strip 812 and knuckle 810. First, as shown in Figure 20, the top hat attachment is positioned near the edge of a panel of the building skin, preferably between the edge of the metal piece 212 and the edge of the panel. The piece of flexible membrane is heat welded to the installed panel membrane, preferably over the whole area of the membrane 1910, to form a seal. Then, assuming in Figure 21, capping strip 812, is fixed to the upper portion of the top hat, preferably in the middle using small self drilling screws or rivets 1858. The top hat in this example is filled with a blocker to protect the fixing length, either before or after welding.

Finally, the knuckle pieces 810, which have in advance been fitted over the capping strip at a distance from the fixing point, are slid over the joints at the ends and mid-way. As before, the knuckle position and attachment locations along the longitudinal seam can be chosen according to the aesthetic look that needs to be achieved.

Using a top-hat arrangement as described provides a larger area of contact to bond the flexible membrane 1910 to the panel membrane, as compared to the example of Figures 17 to 18. For example, the area of the flexible piece of membrane 1910 for the top hat arrangement may be 55mm by 160mm. The raised portion of the top-hat in this example has dimensions of 25mm by 60mm by 20mm (height) and each wing preferably has dimensions of 25mm by 30 mm. The area of the flexible membrane 1910 may extend beyond the area covered by the capping strip and knuckle. For a tidy appearance, however, it is preferred that the edge of the membrane 1910, and indeed the underlying panel membrane 2010, end back from the capping strip hem, labelled 2112 and 2114.

The attachments in this embodiment may be used anywhere on long intersecting' panels in a roof skin that follow a staggered or aligned pattern. Although the roof skin is penetrated by the screw 1854, the neoprene washer 1856, coupled with cover by the capping strip and knuckle, seals the fixing against water ingress from above. The membrane square 1714 prevents water ingress from the side, beneath the attachment, by being welded first to the coating of the metal part 1700 and then welded to the roof membrane 1860 during installation.

In all the fixing methods a desired vertical gap can be arranged between the capping strip hems and the main membranes. This helps to avoid sticking due to self welding, so that differential expansion forces are handled by the designed fixings, not transmitted to the intervening membrane.

The above and many other variants are encompassed within the spirit and scope of the invention in its various broader aspects.

Claims (30)

1. CLAIMS1. A method of installing a building skin on supporting structure, the method comprising: -providing a set of prefabricated panels, each panel comprising a flexible membrane reinforced along at least one edge by being bonded to a strip of relatively rigid material; -fitting a first one of said panels to said supporting structure to form a first unit area of the skin; -fitting a second one of said panels to said supporting structure to form a second unit area of the skin adjacent the first unit area, fixing said rigid material to the supporting structure, so that said reinforced edge of the second panel overlies an edge of the membrane of the first panel which is opposite the reinforced edge of 0) the first panel; -fitting further panels in the manner of the second panel so as to extend the skin area.
2. 2. A method as claimed in claim 1, wherein the rigid material is only partially bonded to the flexible membrane, an unbonded portion of the rigid material is exposed through which the strip is fixed to the supporting structure, and then the membrane is flattened over the fixed strip to cover the strip and an area of the structure.
3. 3. A method as claimed in claim 1 or 2, wherein each prefabricated panel further comprises a lapping strip of flexible membrane material sealed to and projecting beyond the reinforced edge of the panel, the method further comprising the step of bonding said lapping strip to the material of the underlying so as to form a sealed joint between the panels.
4. 4. A method as claimed in any of claims 1, 2 or 3, wherein the bonding is by heat welding polymer said membrane materials.
5. 5. A method as claimed in any of claims 1 to 4, wherein the reinforcing rigid material is a metal such as steel, coated with a polymer layer, the polymer layer then being heat welded to the larger membrane.
6. 6. A method as claimed in any preceding claims wherein the structure is vertical or inclined.
7. 7. A method as claimed in any preceding claims wherein the first, second and further unit areas form a first run of panels, the method comprising a step of laying further runs adjacent to the first run, with edges of the further run of panels overlying the edges of the first run.
8. 8. A method as claimed in claim 7, wherein the edges of the panels in the first 0) run are fixed to the supporting structure prior to addition of the adjacent panels in the second run, the overlying portion of the second run panel then covering the fixing points.
9. 9. A method as claimed in any preceding claim wherein the rigid strip is arranged asymmetrically with respect to the overall width of the membrane panels, to facilitate overlapping of their edges and concealed fixing.
10. 10. A method as claimed in any of claims 7 to 9, wherein the positions of panels within runs are staggered from one run to the next, some runs starting with a shorter panel.
11. 11. A method as claimed in any preceding claim wherein a capping strip is mounted on the longitudinal seam.
12. 12. A prefabricated panel assembly for use in assembling a building skin, the panel comprising a flexible membrane having a weather surface and a rear surface, the membrane rear surface being bonded along at least one edge to a strip of relatively rigid material, the rigid material further having an unbonded portion, whereby in assembling said building skin said unbonded portion can be exposed temporarily to allow fixing the strip onto a supporting structure (either directly or through another panel), the unbonded portion then being re-covered by the membrane in the finished assembly.
13. 13. A panel assembly as claimed in claim 12 wherein the panel further comprises a lapping strip of flexible membrane material sealed to and projecting beyond the bonded edge of the panel.
14. 14. A panel assembly as claimed in claim 12 or 13, wherein the length of the reinforcing rigid material along the bonded edge is less than the whole width of the flexible membrane.

    0)
15. 15. A panel assembly as claimed in any of claims 12 to 14, wherein the rigid strip comprises a wing in the unbonded portion, which extends the length of the rigid strip along the bonded edge, the rigid strip, including the wing portion, lying wholly within the width of the flexible membrane. (\J
16. 16. A panel assembly as claimed in any of claim 12 to 15, wherein the rigid material comprises a hemmed portion formed by bending a portion of the rigid strip, and wherein the hemmed portion is bonded to one end of the membrane edge with the whole width of the flexible membrane substantially folded over the hemmed portion.
17. 17. A panel assembly as claimed in any of claims 12 to 16 wherein the rigid strip comprises a joggle bend portion formed by creating a step along the piece of rigid strip, the step being dimensioned substantially to compensate for the thickness of a similar panel when laid on said supporting structure in an overlapping manner.
18. 18. A panel assembly as claimed in claim 17 wherein the area of the rigid strip away from the membrane edge, beyond the joggle step, comprises the free unbonded portion.
19. 19. A panel assembly as claimed in any of claims 16 to 18 wherein the panel further comprises a lapping strip of flexible membrane material sealed to and projecting beyond the bonded edge of the panel, and wherein the lapping strip is bonded to the whole width of the flexible membrane folded over the curved hemmed portion of the rigid strip.
20. 20. A panel assembly as claimed in claim 19, wherein the flexible membrane folded over the hemmed portion comprises a chamfer near the membrane edges, so that the lapping strip can be bonded, over the chamfered area, to a single layer of the flexible membrane.
21. 21. A panel assembly as claimed in claim 12 to 20, wherein the bonding is by 0) heat welding. °15
22. 22. A panel assembly as claimed in any of claims 12 to 21, wherein the strip of rigid material is a metal such as steel, coated with a polymer layer, the polymer layer then being heat welded to the larger membrane.
23. 23. A panel assembly as claimed in any of claims 12 to 22 wherein the rigid strip is arranged asymmetrically with respect to the overall width of the membrane panels.
24. 24. An installation comprising a supporting structure fitted with a plurality of panel assemblies as claimed in any of claims 12 to 23.
25. 25. An installation as claimed in claim 24 wherein the installation comprises an inclined roof having eaves and a ridge, and wherein a plurality of said panel assemblies are aligned along a longitudinal axis from the eaves to the ridge and overlapping each other to form at least a first run of panels.
26. 26. An installation as claimed in claim 25, wherein the roof has a gable end, the building skin comprising a plurality of runs of panel assemblies, the runs overlapping each other laterally in a sequence running toward or away from said gable end
27. 27. An installation as claimed in claim 24, 25 or 26, wherein the building skin comprises a plurality of runs of panel assemblies, adjacent runs of assemblies being staggered relative to each other to create a broken bond effect.
28. 28. A kit for the production of a panel assembly for use in forming a building skin, the kit comprising: a flexible membrane; a strip of relatively rigid material to be bonded at one edge of a flexible 0) membrane, to form a panel assembly for use to form a building skin, thereafter comprising a bonded and unbonded portion, and whereby in assembling said building skin said unbonded portion can be exposed temporarily to allow fixing the strip onto a supporting structure (either directly or through another panel), the unbonded portion then being re-covered by the flexible membrane in the finished assembly; and a lap strip to be bonded on an edge of a flexible membrane.
29. 29. A method of producing a panel assembly for use to form a building skin, the method comprising: bonding a strip of relatively rigid material to one edge of a flexible membrane to form a panel assembly, leaving unbonded a portion back from the membrane edge, thereby to form a panel assembly as claimed in any of claims 12 to 27.
30. 30. A method as claimed in claim 29 wherein a lapping strip of flexible membrane material is fitted, sealed to and projecting beyond the bonded edge of the panel.