GB2609609A

GB2609609A - Cabin

Info

Publication number: GB2609609A
Application number: GB2110835.2A
Authority: GB
Inventors: Williams Barry
Original assignee: N L Williams Group Ltd
Current assignee: N L Williams Group Ltd
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2023-02-15
Anticipated expiration: 2041-07-28
Also published as: GB2609609B; GB202110835D0

Abstract

The present invention relates to a cabin, particularly a cabin having an outer shell structure. The cabin has a shell covering at least a portion of the cabin and comprising a sheet material formed into an arch. The sheet material comprises corrugations extending helically over the arch. The corrugations may be angularly offset from an axis of the arch by between 1 and 45 degrees. The corrugations may be curved or sinusoidal. The cabin may comprise a frame for supporting the shell and arranged to define a cabin interior. Side walls of flat sheet material may be provided. The cabin may comprise multiple stories or levels. The sheet materials may be metals and may have a protective coating. A plurality of arches may be combined to form a common shell.

Description

The present invention relates to a cabin, particularly a cabin having an outer shell structure.

Introduction

Cabins have a variety of uses in different technical fields. This has given rise to a large number of variants that are tailored specific to their type of application. Some examples are bike shelters, residential cabins, garden rooms, storage cabins and commercial units for a variety of purposes such as street vendors, hospitality space, kiosks as well as more permanent structures for dining, meeting, on-site welfare and the like.

Some existing cabins are constructed using a frame structure with an external shell or wall covering at least some portion of the frame defining an interior. The extent to which the shell covers the frame is dependent on the application. For example, habitable cabins are often completely covered, whereas bike shelters are generally only partially covered.

A very early example of simple cabin structures can be seen in the Anderson Shelter, which involved the use of inexpensive corrugated sheet to provide a shell for the shelter. Such an arrangement was adopted during war times for specific purposes and is generally not considered suitable for most modern-day cabin requirements.

There has been an increased demand in recent years for prefabricated cabins, e.g. made from a metal frame with a sheet material covering. This allows them to be more mobile and easier to assemble. They are also versatile as they can be modified to the owner's specific field of use. As a result, prefabricated cabins are becoming increasingly popular for a variety of uses in the retail, service, construction and hospitality industries.

As such, the use of free-standing, modular cabins has been acknowledged in the art in order to provide simple construction and transportation, i.e. to facilitate quick and cost-effective installation for a variety of purposes.

The inventor has found numerous drawbacks with the prior art. Conventional cabins can be prone to damage, particularly where flat walls and roofs are provided without an adequate supporting frame structure. Damage can occur during handling, construction or when erected, e.g. due to excess loading or impact in flat wall structures. When the cabin is subjected to extreme weather conditions, the resulting wear and tear can result in the cabin no longer being weatherproof or fit for purpose. Cabins may therefore have a limited service life or may need to be regularly serviced and repaired, increasing the cost for the owner.

To mitigate these problems, manufacturers will compensate by adding additional frame members or more robust materials. However, these remedies typically involve increasing both the weight & cost of the cabin.

Furthermore, the roof of the cabin is particularly important since it represents a large area which must remain weatherproof. As such, a significant focus of the frame structure of existing cabins is directed towards supporting the roof. This requires frame members extending beneath the roof to support it over its area.

It is the aim of the present invention to mitigate or overcome one or more of the problems presented above. It may be considered an additional or alternative aim to provide a cabin that is simple in construction whilst remaining structurally fit for purpose.

Statements of Invention

According to the present invention there is provided a cabin comprising a shell covering at least a portion of the cabin, the shell comprising a sheet material formed into an arch, wherein the sheet material comprises elongate formations that extend helically over the arch.

The elongate formations may be formed in the shape/profile of the sheet material. The formations may comprise corrugations and/or seams.

The helical corrugation arrangement allows the cabin shell (e.g. the sheet material itself) to be self-supporting such that it does not require any supports to maintain its shape, even when subjected to both lateral and/or vertical loading. The shell structure of the present invention does not bend or bow, and therefore provides superior roofing or other shell portion of a cabin compared to those found on Anderson cabins in the prior art. The shell can thus provide both a weather-proof or water-proof skin for a cabin as well as a structural member of itself, e.g. as a simple, single layer shell structure.

The corrugations may extend in a direction which is angularly offset from an axis of the arch by an angle of 1 to 45 degrees.

The corrugations may be curved or sinusoidally shaped, e.g. in section.

The corrugations may be spaced apart such as to define an intermediate sheet material portion between two adjacent corrugations.

The cross-sectional shape of the arch may follow the path of an arc of a circle or ellipse.

The arch may extend substantially 180 degrees around an axis of the shell or the cabin.

Preferably, the arch of the shell has a width or diameter of greater than 1 meter.

Preferably, the arch of the shell has a maximum width or diameter of less than or equal to 5 meters.

The cabin may comprise a frame for supporting the shell. The framemay be arranged to define a cabin interior.

Preferably, the frame members extend in a direction substantially aligned with an edge of the shell and/or the frame members do not extend across a mid-portion of the arch when viewed in plan. The frame members may define edges, corners or structural portions of walls beneath/behind the shell.

The frame members may be attached only in the vicinity of an edge of the shell arch.

Preferably, where the arch is self-supporting and/or weight bearing, e.g. wherein the arch bears additional weight thereon in use.

The cabin may comprise side walls made from a substantially flat sheet material.

The arch may have an axis that extends longitudinally through the cabin defining a first and second end, where the first and second ends each comprise an edge. Corrugations at/adjacent the edge may be parallel to the edge.

The cabin may comprise multiple stories.

Preferably, the sheet material is comprised from a metal such as steel. The sheet material may be treated or coated. Galvanised steel may be used.

Preferably, the cabin is fully recyclable.

The sheet material may form an exterior shell of the cabin.

Preferably, the cabin comprises a seam extending parallel with the corrugations and/or in-between adjacent corrugations. The seam may comprise an overlapping and/or interlocking portion if the sheet material. The seam may comprise a strengthening seam, e.g. providing additional hoop strength.

Preferably, the sheet material is comprised of rows, extending in the helical direction and each joined to an adjacent row along the seam, where the seam comprises an overlapping and/or interlocking portion of adjacent rows. Rows of sheet material may be wound around the arch.

The cabin may comprise a plurality of sheet material arches connected together to form a common shell, where one sheet material arch may be angularly offset from an adjacent sheet material arch.

A second aspect of the invention is for a modular cabin system comprising, a plurality of shells arranged to cover at least a portion of the modular cabin system, each shell comprising a sheet material formed into an arch, wherein the sheet material comprises corrugations extending helically over the arch of its shell, the shells being linked at an interface.

Preferably, the interface portion comprises a passage suitable for allowing persons to move between the plurality of shell portions.

According to a third aspect of the invention, there is a method of manufacture for a cabin shell comprising the steps of; a) shaping a sheet material to define a plurality of corrugations therein, and b) winding the sheet material helically along a longitudinal axis to form a tubular shell.

Preferably, the manufacturing method comprises the additional step of; c) cutting the tubular shell to form an arch having a discrete arc length about the longitudinal axis.

The method may comprise joining each turn of the sheet material to an adjacent turn, e.g. so as to form a seam. The joining may be performed during winding.

Preferably, the manufacturing process is continuous. Step (b) may immediately follow step (a)..

According to a fourth aspect of the invention, there is provided a cabin comprising a shell covering at least a portion of the cabin, the shell comprising a plurality of strips of a sheet material formed into an arch, wherein the strips are elongate in form and arranged side by side with each strip extending in a helical direction over the arch.

Any optional feature defined in relation any one aspect above may be applied to any further aspect, where practicable.

Workable examples of the invention are described in further detail below with reference to the accompanying drawings, of which: Figure 1 shows a three-dimensional view of shell structure as according to the invention.

Figure 2 shows a top-down view of a shell structure as according to the invention.

Figure 3 shows a schematic cross-section through a portion of the shell structure.

Figure 4 shows a schematic side view of a manufacturing process for the shell structure.

Figure 5 shows a schematic three-dimensional view of sheet material being formed into a tubular shape.

Figure 6 shows a three-dimensional view of a fully assembled cabin according to one embodiment of the invention.

Figure 7 shows front and side views of an assembled cabin.

Figure 8 shows a three-dimensional wireframe view of a further cabin layout.

Figure 9 shows a wireframe view of a further cabin configuration.

Detailed Description of Embodiments of the Invention The invention derives from the concept of using a tubular pipe-type structure as the shell/roof of a cabin. The tube can be cut in an axial direction to form an arched shell structure. Where tubes are formed to have good weight bearing properties, i.e. offering good hoop strength (e.g. due to using a corrugated profile), the arch formed therefrom is well adapted to provide a self-supporting roof.

Shell structure Figure 1 shows a shell structure 1 of one embodiment of the invention. The shell structure is formed from a sheet metal that is shaped into an arch around an axis 2 that extends longitudinally through the shell. As can be seen from the figures 1 & 2, the shell is self-supporting such that it does not require any underlaying frame structure to maintain its shape.

Best shown in figures 2 and 3, the sheet metal of the shell structure 1 is shaped to define corrugations 3, i.e. spaced elongate peaks and/or troughs running over the arch and around the axis 2. The corrugations 3 extend helically with respect to the longitudinal axis 2. That is to say, the corrugations extend in a direction that is neither parallel with, nor perpendicular to, the axis 2, ie. the angle is obliquely offset.

The helix angle 4 is defined to be the angle that the corrugations 3 make with respect to an axis 5 that is perpendicular to the longitudinal axis 2. In the embodiment shown in figure 2, the helix angle is approximately 5 degrees although it is appreciated that it may be anywhere between 1 and 45 degrees. The angle is preferably less than 30 degrees, 20 degrees or 10 degrees.

The plurality of corrugations is continuous in this example, ie with each corrugation adjoining an adjacent corrugation. However in other examples the corrugations could be spaced apart, eg by a flat or straight intermediate portion between adjacent corrugations.

The corrugations are curved in this example, ie generally sinusoidal in profile as shown in figure 3 but they could take other forms, provided they take the form of elongate protrusions or depressions in the sheet material. For example, instead of being sinusoidally shaped, the helical corrugations may comprise one or more distinct corners such as to be substantially triangular, square or any other polygonal shape.

Figures 1 & 2 show that the arch of the shell extends substantially 180 degrees around the longitudinal axis such as to be semi-circular in appearance. The arch follows the path of an arc of a circle when viewed end on.

In other examples, the path may be elliptical and/or extend anywhere between 90 and 360 degrees about the longitudinal axis depending on the extent/arch of the shell structure that is required.

The width and length of the shell may be tailored to the specific field of use. Where the arch of the shell is circular about the longitudinal axis, the diameter of the arch may be between 1 and 5 meters. Where the shell is elliptically shaped, the arch may have a minimum width/diameter of 1 to 5 meters. The diameter may be greater than 1, 2 or 3 metres. The diameter may be less than 6, 5 or 4 metres.

The length of an individual shell portion (ie. the axial length) will typically be greater than 2 or 3 metres. The length can be up to 5, 10 or 14 meters long however, as described below, multiple shells can be joined longitudinally to create any desired length.

As can be seen in figure 3, the shell structure 1 may be formed from a plurality of strips or rows 6, 7 of the sheet material that are joined side by side at a seam 8.

The seam 8 comprises the interface between the opposing edges of the strips 6, 7. The seam 8 may comprise overlapping or abutting edge portions of the adjoining strips 6, 7.

The edge of either or both strips 6, 7 may be profiled in the vicinity of the seam, e.g. to define an edge formation to receive the opposing edge. In the example shown, the strip 6 is profiled at its edge to form a recess or channel in which the edge of strip 7 is received. Other profiled arrangements are possible to for a secure join between strips of the sheet structure. This allows a desired axial length of the sheet structure to be built up using a simple manufacturing process as will be described below.

The seam provides structural strength in the helical direction in addition to, or instead of, the corrugations. In some embodiments, if the width of each strip is selected carefully such that the seams provide sufficient hoop strength, the corrugations in the sheet material of the shell may not be required. This may be suitable in particular for smaller cabins, e.g. sheds or WC cabins.

The shell is formed from a metal, preferably galvanised steel and provided with a protective coating. The coating may be a paint or other suitable waterproof and/or weatherproof coating. However, other materials such as treated aluminium or polymers or composite panels could potentially be used for the shell structure, provided the strength to weight ratio is practicable.

Manufacturing process Figures 4 and 5 show the manufacturing process for a helically wound pipe 10 that can be used to form a structure such as the embodiment shown in figure 1-2.

As shown in figure 4, a sheet material 11, e.g. sheet galvanised steel is first passed through formers in the form of rollers 12 that deform the sheet 11 into the desired cross-sectional profile. The formers may comprise opposing sets of rollers 12 that interfere so as to define a tortuous path between the rollers, thereby deforming the sheet material into the desired profile when fed between the rollers.

In this example, the opposing rollers are evenly, intermittently spaced so as to form the continuous sinusoidal corrugations extending along the length of the sheet material. The shape of the corrugations correspond to the arrangement of the rollers and so it will be appreciated that other roller arrangements could be used to form different profiles. In any such embodiment, the profile of the sheet material will vary in height across its lateral/width dimension before being formed into a tubular shape.

After the sheet material exits the formers, it is fed through a further set of rollers 13 which deform the profiled sheet material in a tangential direction so as to form the arc of a circle so as to form a tube 10 as shown in figure 5.

The sheet material is fed at an angle with respect to the longitudinal axis 2 of the tube 10 such that it wraps around its external surface in a helical manner, defining a plurality of turns which allows for the tube 10 to be extended to the desired length in the axial direction.

The width 'W' of the sheet material 11 defines the width of each strip or turn of the helically wound tube 10. For each turn of the sheet material 11 around the axis 2, the pipe length advances by an axial length W. A hollow pipe is thus formed with the desired formations (ie corrugations and/or seams) extending helically around its bore. The pipe 10 has a diameter, D, defined by the angle at which the sheet material is turned by rollers 13 and a length defined in general terms by n x W, where 'n' is the number of rotations of the sheet material 11. It will be appreciated that any overlap of the edges of adjacent turns of the sheet material will reduce the actual length of the pipe 10 so it is not exactly n x W. Prior to the operation, the rollers 13 can be calibrated to the desired width of the tube 10 which is in the range of 1 to 5 meters.

As the material is fed from the former 12, it may enter a further crimping/shaping tool that forms a desired edge profile to create an interlock between the opposing edges of each turn of the sheet material 11, ie a seam profile. The seam may be comprised of an overlapping portion of two adjacent rolls that are bent and pressed by the crimping tool forming a watertight seam.

As the tube is formed, it continually advances along the axis 2 allowing for the process to be continuous. When the tube has reached the desired length with the seams and corrugations extending helically over the surface, the tube is cut by a floating saw to form a discrete tube 10 section, eg whilst still simultaneously forming the next tube.

The discrete tubular structure is then further processed as desired. The end edges of the tube 10 can then undergo a process called 'end-rolling' in which the corrugations are re-shaped for the purposes explained in detail later. This can form a cuff or collar arrangement at either or both ends of the tube 10.

In order to form the shell structure 1 shown in figures 1 and 2, the tube can then be cut along its length such as to form the arched shell portion that is required for a cabin. For example, to form the shell structure shown in figures 1 & 2, the circular tube is cut longitudinally on diametrically opposing sides such as to form two semi-circular shell portions. Both of the cut-away portions are suitable for use as shell structures such as to minimise waste.

In other examples, the tube 10 could be cut in thirds or quarters, or at any desired arc length, so as to define different shell shapes. In some examples, the tube 10 need not be cut in a direction that is parallel to axis 2 but is instead obliquely angled. This would form a tapered shell structure that may be suitable for some specific structural designs.

A shell structure formed in this manner from a single sheet material offers excellent weight bearing properties for use as a structural element of a building/cabin. The shell structure is efficient and cost-effective to produce and can be treated/coated as required to form the outer skin of a habitable structure.

The shell structure 1 in figures 1 and 2 could serve as a simple shelter in its own right. However it is proposed that the shell structure 1 can also be used as a component in a wide variety of cabin and building designs.

Cabin Structure The shell structure 1 itself may form a simple enclosure. This may be suitable for a basic shelter, e.g. as a shed, shelter or store room.

In some examples, walls defining the perimeter of a cabin can be erected and the shell structure 1 mounted thereto. However it is also proposed that a frame-based construction for the walls of a cabin can be used to provide a modular design, i.e. a free-standing and self-supporting cabin structure that is simple to customise to an end user's needs.

An example frame structure for a cabin is shown in figure 6. The structure comprises a plurality of frame members 15 arranged such as to define side walls 16, end walls 17 and flooring 18 as well as an interior space. In the embodiment shown, the frame structure comprises a plurality of substantially straight and curved members.

The straight frame members 15 are arranged such as to form the supports for planer panels along the walls and flooring. Panels of any suitable material may be attached to the frame in a conventional manner, e.g. The frames in the end walls are arranged to form struts allowing for the installation of doors and/or windows. using conventional fasteners/fixings.

The frame comprises a curved frame member 15a at each of the end walls that extends from a first to a second side wall 16 in this example. The curved frame members 15a are contoured to receive the shell structure shown in figures 1 & 2, ie the underside thereof.

The frame structure principally defines the height of the cabin beneath the shell 1.

As the shell structure is self-supporting, the frame is able to support the shell structure with only two curved frame members provided at each end wall without the need of interstitial curved members or longitudinal supports being welded to the interior surface of the shell. In other examples, such curved frame members 15 may not be needed and the shell 1 may be supported only at its lower edge by frame members 15.

The metal shell 1 can be attached to the frame members 5 using any conventional sheet metal fastening techniques. The join/fastenings are preferably weather-proof, e.g. capable of withstanding temperature variations and moisture without corrosion or allowing water ingress. Conventional fasteners are an option, such as bolts, rivets, etc. However it has been found that welding the frame members to the interior face of the shell can provide a suitable join without the need to penetrate through the wall thickness of the shell. This may have long-term benefits for weatherproofing such that there is no exposed element of a fastener on the external face of the shell. The entire external surface of the shell can be uniformly treated or coated. Figure 7 shows a simple version of a fully assembled cabin 20 comprising the shell structure 1 of figures 1-2 and the frame structure, including panel walls, of figure 6.

The shell 1 may be secured to the frame structure along the curved frame member 5a, e.g. continually, at the first and second end wall. The side and end walls are covered with planar sheets such as to enclose the interior space fully. One end wall is also fitted with a door in this example.

As the shell is self-supporting and offers improved strength over the prior art, the number of frame members required is reduced. Therefore the cabin is more light weight, cheaper to transport and is more sustainable over the prior art.

Although the structure shown in figure 7 is relatively simple in design, more complex structures are possible, such as to comprise a variety of internal rooms, layouts or configurations. For example, multiple shell structures can be joined in a single cabin to increase internal floor space or to provide multiple stories.

The cabin can be tailored to the specific application of use. For example, two or more shells can be joined at an interface 21 as shown in figure 8 to build longer structures. This example represents an end-to-end shell structure arrangement, forming a tunnel-like cabin. The internal space can be partitioned as desired, e.g. with an internal wall at the interface 21 to align with the frame structure and/or with partitions at any desired longitudinal spacing.

Shell structures could also be attached/joined side-by-side to increase the width of a cabin, e.g. producing a cabin with a plurality of arches. A join can thus be made along a lateral/straight edge of the shell 1. An upright frame member 15 may be provided below the joined edges to support the weight of the shell part-way along the total edge of the cabin.

The shells and/or cabins could then be construed as compartments as part of a greater cabin structure. This would allow persons to move between the compartments.

In some examples, the interface need not be a common interface at the edges of the adjacent cabins but rather adjacent cabins could be joined by an intermediate structure. The intermediate structure could be in the form of a semi-permanent tunnel, passage or walkway. Thus a plurality of discrete or spaced cabins can be joined as an interconnected internal/undercover space.

Alternatively, the interface could be a pivotable hinge connecting the compartments that brings a passable opening in each compartment together. The compartments may be abutting another such that the interface is a joint. Where the compartments are joined longitudinally, the joint can comprise a coupling band and gasket.

More complex designs are also envisioned. In an alternative embodiment, as shown in figure 9, the principles defined above may be used to create a multistorey cabin structure. In this example, a half-pipe has been cut in two to provide two separate shell structures la and 1 b, e.g. each comprising a 90 degree arc. The two shell structures have been offset in height with the shell la being raised relative to the shell 1 b. The shell la thus covers a two-storey portion of the cabin, whilst the portion covered by the shell lb is a single storey.

It is to be noted, that the shell structure is not limited to use as a roof of a cabin. If the axis 2 of the cabin is arranged in a substantially vertical direction, the shell structure 2 may form a curved side wall of a cabin or other type of building. An example is shown in figure 10, where shell structures lc are provided in this upright configuration to provide cylindrical pods. In this example, the pods are attached to a main cabin 20a. However in other examples, they could be freestanding as cabins in their own right. Furthermore, such a pod could be provided as an extension to an existing structure such as an existing building. For example, where it is desired to provide an external lift shaft or similar extension to an existing building, a shell structure of the type described herein could be provided as an efficient and easy to install solution.

A multistorey cabin according to the invention may also comprise a stairway or an elevator, which could be housed in a dedicated shell structure, e.g. separated from the main compartment, in the form of the shell structures lc discussed above.

The cabins are also suitable for subterranean use as permanent living accommodation, e.g. with the weight of any earth upon the cabin being borne by the shell structure.

The cabin can be tailored to the particular field of use. For example, the cabin may have electricity wired such as to have power sockets and Fighting. The cabin may be powered by the mains, or by renewable energy sources and may comprise solar and/or wind power generating devices. The cabin may have plumbing for hot water and toilet facilities.

The interior surface of the shell structure and/or cabin walls may be lined with thermal and/or sound insulating material.

Since the shell structure does not need any significant additional support, it can reduce the amount of metal/steel needed to erect a cabin. The corrugated structure can reduce the gauge of the sheet material needed to provide adequate strength, e.g. using a 2-3.5mm gauge (subject to the diameter of the shell), when compared to a planar rolled body. Also the steel can be recycled at the end of life of the cabin.

In some examples, the valleys in the corrugated shell structure could provide ready pathways for installation of pipework/ducting or cabling inside the shell structure. For example thermal gain pipes could run along the valleys for heating or hot water applications.

The versatility of the cabin makes it ideal for a number of applications. For residential purposes, the cabin can be used as a modular home, a garden room, office rooms, home gyms, emergency or social housing and holiday homes. For commercial purposes, the cabin is suitable for pop-up sales modules, market stalls or artisan events, gyms, welfare units, IT hubs, CCTV and HiViz units. For industrial purposes the cabin is suitable for workshops, garages, spray booths, smoking shelters, offices, break out/meeting rooms, canteens, decontamination units. For educational purposes the cabin can be used as classrooms, fitness suites, or quiet zones.

Claims

Claims 1. A cabin comprising: a shell covering at least a portion of the cabin, comprising a sheet material formed into an arch, wherein the sheet material comprises corrugations extending helically over the arch.
2. A cabin according to claim 1 wherein the corrugations extend in a direction which is angularly offset from an axis of the arch by an angle of 1 to 45 degrees.
3. A cabin according to claim 1 or 2, wherein the corrugations are curved or sinusoidally shaped.
4. A cabin according to any preceding claim 3, wherein the corrugations are spaced apart such as to define a intermediate sheet material portion between two adjacent corrugations.
5. A cabin according to any preceding claim, where a cross sectional shape of the arch follows the path of an arc of a circle or ellipse.
6. A cabin according to claim 5, where the arch extends substantially 180 degrees around the cabin.
7. A cabin according to claim 1, where the arch of the shell has a width or diameter of greater than 1 meter.
8. A cabin according to claim 1, where the arch of the shell has a maximum width or diameter of less than 5 meters.
9. A cabin according to any previous claim, wherein the cabin comprises a frame for supporting the shell and is arranged to define a cabin interior.
10. A cabin according to claim 9, where the frame members extend in a direction substantially aligned with an edge of the shell and/or where the frame members do not extend across a mid-portion of the arch when viewed in plan.
11. A cabin according to claim 9 or 10, where the frame members are attached only in the vicinity of an edge of the shell arch.
12. A cabin according to claim 11, where the arch is self-supporting and/or weight bearing.
13. A cabin according to claim 9, comprising side walls comprised from substantially flat sheet material.
14. A cabin according to any of the previous claims, where the arch has an axis that extends longitudinally through the cabin defining a first and second end, where the first and second ends each comprise an edge, where corrugations adjacent to the edge are parallel to the edge.
15. A cabin according to any of the previous claims, where the cabin comprises multiple stories.
16. A cabin according to any of the previous claims, where the sheet material is comprised from a metal.
17. A cabin according to claim 16, where the shell is provided with a protective coating.
18. A cabin according to any preceding claim comprising a strengthening seam extending parallel with the corrugations.
19. A cabin according to claim 18, comprising a plurality of rows of sheet material, each extending in the helical direction and each joined to an adjacent row along the seam, where the seam comprises an overlapping portion of adjacent rows.
20. A cabin as according to any of the previous claims, comprising a plurality of sheet material arches connected together to form a common shell, where one sheet material arch is angularly offset from an adjacent sheet material arch.
21. A modular cabin system comprising: a plurality of shells arranged to cover at least a portion of the modular cabin system, each shell comprising a sheet material formed into an arch, wherein the sheet material comprises corrugations extending helically over the arch of its shell, the shells being linked at an interface.
22. A modular cabin system according to claim 21, where the interface portion comprises a passage suitable for allowing persons to move between the plurality of shell portions.
23. A method of manufacture for a cabin shell, comprising the steps of: a) shaping a sheet material to define a plurality of corrugations therein, and b) winding the sheet material helically along a longitudinal axis to form a tubular shell.
24. A method according to claim 23, comprising the additional step of: c) cutting the tubular shell to form an arch having a discrete arc length about the longitudinal axis.
25. A method according to claim 23, where step (b) immediately follows step (a) such that the formation of the tubular shell is a continuous process.