This invention relates to building structures, and in particular to building structures having walls which must provide a certain level of thermal insulation.

In many countries regulations are in place governing the level of thermal insulation that must be provided by external and/or internal walls of structures in which people will live and/or work, such as houses, offices and other commercial premises, and hotels.

Conventional insulating internal walls in modern structures are formed by providing generally parallel opposing sheets of material, such as gypsum or chipboard, having a gap or cavity therebetween. This gap is then filled with insulation material such as a rigid foam or a mineral wool.

This conventional construction suffers from drawbacks, however. It can be difficult to control the level of thermal insulation that is achieved. Also, over time the properties of the insulation material are likely to change, thus reducing the level of thermal insulation that is provided.

It is an object of the invention to provide an improved construction of this type.

Accordingly, one aspect of the present invention provides a wall of a building structure, the wall comprising: inner and outer face surfaces formed from glass fibre reinforced board; a support structure comprising one or more rigid components positioned between the inner and outer face surfaces; and a quantity of low-density cellular lightweight concrete (CLC) which substantially fills the space between the inner and outer face surfaces.

Advantageously, the inner and outer face surfaces are substantially parallel with each other.

Preferably, the density of the CLC is less than 200 kg/m ³ .

Conveniently, the face surfaces are formed from glass fibre reinforced concrete (GRC).

Advantageously, the low density CLC substantially fills the space between the inner and outer face surfaces over the entire height of the wall. Preferably, the inner and outer face surfaces are attached to, and supported by, the support structure.

Conveniently, the face surfaces are spaced apart from the support structure, to provide a gap between the support structure and each of the face surfaces.

Advantageously, the inner and outer face surfaces are each formed from a plurality of sheets of glass fibre reinforced board. Preferably, the support structure comprises a series of spaced-apart supports, and each sheet is attached to at least one of the supports.

Conveniently, each support has an inner side and an outer side, sheets of the inner face surface are attached to the inner side and sheets of the outer face surface are attached to the outer side.

Advantageously, each sheet has widened regions at opposing edges thereof, with a narrower region between the widened regions. Preferably, each sheet has widened regions at each of its edges.

Conveniently, the support structure is entirely or substantially formed from light gauge steel (LGS). Another aspect of the present invention provides a building structure incorporating a wall according to any one of the above.

A further aspect of the present invention provides a building structure comprising two or more walls, each according to any one of the above, wherein the low density CLC within the two or more walls comprises a unitary, continuous and unbroken quantity of CLC.

Advantageously, the building structure further comprises a ceiling or a floor, which forms part of the same storey of the structure as the wall(s), wherein the floor or ceiling comprises at least one face surface formed from glass fibre reinforced board, and the floor or ceiling contains a quantity of low-density CLC which forms a unitary, continuous and unbroken quantity of CLC along with the CLC which is within the wall(s). Preferably, the building structure comprises two or more stories, each including one or more walls according to any one of the above.

Another aspect of the present invention provides a method of forming a wall of a building structure, the method comprising: providing inner and outer face surfaces formed from glass fibre reinforced board; providing a support structure, comprising one or more rigid components positioned between the inner and outer face surfaces; and pouring a quantity of low-density CLC into the space between the inner and outer face surfaces, so that the low-density CLC substantially fills the space between the inner and outer face surfaces.

Conveniently, the method comprises: providing the support structure; attaching the outer face surface to the support structure; and attaching the inner face surface to the support structure.

Advantageously, the method further comprises the step, after the step of attaching the outer face surface to the support structure, but before the step of attaching the inner face surface to the support structure, of installing components of one or more service, such that, once the step of attaching the inner face surface to the support structure has been completed, the components of the one or more service are located between the inner and outer face surfaces.

Preferably, the components of the one or more service include one or more of power cables, water pipes, data cables, and ventilation components.

Conveniently, the method comprises providing an inner and outer face surfaces for one or more further walls; and pouring the quantity of low-density CLC so that the spaces between the inner and outer face surfaces of all the walls are simultaneously filled.

Advantageously, the method further comprises the step of providing one or more further face surfaces to define a ceiling space, above the walls, or a floor space, below the walls; and pouring the quantity of low-density CLC so that the walls and the ceiling space of floor space are filled, or partially filled, with the low-density CLC in one operation.

Preferably, the method comprises the steps of: placing face surfaces of glass fibre reinforced board to define internal spaces for one or more walls, and for a ceiling space above the walls, or a floor space below the walls, wherein the internal spaces for the one or more walls and the ceiling space or floor space are in fluid communication with each other; and pouring a quantity of a low- density CLC to fill, at least partially, the internal spaces for the one or more walls and the ceiling space or floor space in one operation.

Conveniently, the method comprises the step of filling or substantially filling the internal spaces for the one or more walls, to the full height of the walls, in the one operation. Advantageously, the method comprises the steps, for a single storey of the building structure, of: dividing the storey into two or more sections, each section including one or more walls and part of the ceiling space or floor space; pouring a first quantity of the CLC into the first section to fill, at least partially, the internal spaces for the one or more walls and the part of the ceiling space or floor space in a first operation; and pouring a second quantity of the CLC into the second section to fill, at least partially, the internal spaces for the one or more walls and the part of the ceiling space or floor space in a second operation. A further aspect of the present invention provides a method of constructing a wall of a building structure, the method comprising: receiving a minimum insulation value for the wall; providing inner and outer face surfaces formed from glass fibre reinforced board; from the insulation properties of the inner and outer face surfaces, and of a low-density CLC, calculating the thickness of CLC that must be present between the inner and outer face surfaces in order for a wall, comprising the inner and outer face surfaces with the space therebetween substantially filled by the low-density CLC, to have an overall insulation which is equal to or greater than the minimum insulation value; placing the inner and outer face surfaces at a distance from one another which is at least as great as the calculated thickness; and filling the space between the inner and outer face surfaces with the low-density CLC.

Preferably, two or more walls of the same storey of the building structure have different minimum insulation requirements, the method comprising the steps of calculating the thickness of the low-density CLC that must be present between the inner and outer face surfaces of each wall in order for each wall to meet its minimum insulation requirement; placing the inner and outer face surfaces of each wall at a distance which will allow the finished wall to have an insulation value which is equal to, or greater than, the minimum insulation value for each respective wall; and filling the inner and outer face surfaces of each wall with the same quantity of low-density of CLC in a single operation.

Another aspect of the present invention provides a method of constructing a wall of a building structure, the method comprising the steps of: receiving a minimum insulation value for the wall; receiving a maximum thickness for the wall; calculating a minimum density for a low-density CLC wherein, for a finished wall of a thickness which is equal to or less than the maximum thickness comprising the inner and outer face surfaces with the space therebetween substantially filled with the low-density CLC, will have an insulation value that is equal to or greater than the minimum insulation value; preparing a low-density CLC having at least the calculated density; and pouring the low-density CLC into the space between the inner and outer face surfaces, so that the low-density CLC substantially fills the space between the inner and outer face surfaces.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a series of supports suitable for use with the present invention;

Figure 2 shows the supports of figure 1 along with an outer face surface; Figure 3 shows the supports of figure 2 with both inner and outer face surfaces;

Figure 4 shows a side view of panels, used to form a face surface, attached to one of the supports;

Figures 5 and 6 show a wall embodying the present invention before and after the wall is filled with CLC, respectively;

Figure 7 shows one examples of a panel suitable for use in forming an outer face surface;

Figure 8 shows a stage of formation of two walls and a ceiling, in accordance with the invention; and Figure 9 shows a more close-up view of the junction of the walls and the ceiling.

The construction of a single wall will be described in the first instance, by way of illustration of some of the principles of the present invention.

With reference firstly to figure 1 , a first stage in the construction of a wall embodying the present invention is shown. A number of spaced-apart vertical supports 5 are first installed in position, to provide a support structure for the wall. Three supports 5 are shown in figure 1 , although any number of supports may be used. The supports 5 shown in figure 1 are aligned with each other, and this will generally be preferred for the construction of a straight wall. However, the skilled reader will understand that the supports may be arranged in any suitable manner, depending on the shape and size of the wall to be constructed.

In the example shown in figure 1 , each of the supports 5 takes the form of a column having an omega profile. Each support 5 has a rear wall 32 and two side walls 33, and one open face 34, which is substantially opposite the rear wall 32. A pair of lips 35 extend inwardly from free edges of the two side walls 33, partially occluding the open face 34.

The invention is not limited to this, however, and any suitable kind of support elements or structure can be used with the invention, including beams, rods or girders. The elements of the support structure may be arranged in a lattice, may comprise a series of generally parallel members, or otherwise be arranged in any other suitable way to provide the required support for the intended finished structure.

The supports 5 are preferably fixed in place with respect to the ground. Each support 5 may be, for example, 0.2 to 0.3m wide, although the invention is not limited to this. In preferred embodiments of the invention, the supports 5 are formed from light gauge steel. In preferred embodiments, all or substantially all of the components of the support structure are formed from light gauge steel. The thickness of the components of the support structure is preferably no more than 3mm. As a next step, a first or outer face surface 1 is installed, attached to and supported by one of the side walls 33 of each of the supports 5, as shown in figure 2. The first face surface 1 preferably comprises a continuous or substantially continuous planar surface, which extends over all or substantially all of the height of the intended finished wall. In figure 2 the first face surface 1 and the supports 5 are of substantially the same height, although in practice the supports 5 may be higher than the first face surface 1 , as will be explained in more detail below. The first face surface 1 preferably extends down to ground level.

The spaces between the supports 5 will, once the wall is complete, be within the wall itself. As a next step, other components that are required to be ultimately embedded or contained within the wall are positioned between, and/or attached to, the supports 5. For example, water/plumbing pipes, electrical cables and/or ventilation components (“services”) may be installed at this stage.

Some of these components may need to pass through one or more supports 5. Access slots or apertures (not shown) may be provided through the supports 5 as needed to allow the service components to be installed in required places and extend through the wall to desired locations.

As a next step, shown in figure 3, an inner or second face surface 2 is installed on the opposite side of the supports 5 from the first face surface 1. The face surfaces 1 , 2 are preferably generally parallel with each other.

The face surfaces 1 , 2 are preferably formed from glass fibre reinforced board. As the skilled reader will be aware, glass fibre reinforced board takes the form of sheets of material comprising glass fibre held together by suitable substrate. In preferred embodiments of the invention, the face surfaces 1 , 2 are formed from glass fibre reinforced concrete (known as GFRC or GRC). As the skilled reader will be aware, GRC consists of glass fibres (preferably high-strength and/or alkaline-resistant glass fibres), embedded in a concrete matrix. GRC can be produced by a spray procedure or a premix procedure. While either is possible with the present invention, using a premix approach is preferred. It is also preferred that the proportion of glass fibres in the GRC is at least 1 %.

In preferred embodiments of the invention, the face surfaces 1 , 2 are each formed from a plurality of sheets of GRC. For instance, sheets of approximately 1 m by 1 m may be produced, and arranged edge-to-edge to make up each of the face surfaces 1 , 2. Sheets of this size may readily be produced on-site, thus increasing the efficiency and adaptability of the building procedure.

Each of the sheets may be attached directly to a side surface 33 of one of the supports 5. For example, a first support 5 may have a series of sheets attached thereto extending from the ground up to the top edge of the face surface 1 , 2, with the top edge of each sheet lying against the bottom edge of the next-highest sheet. An adjacent second support 5 may also have a series of sheets attached thereto, with a side edge of each sheet attached to the second support lying against a side edge of a sheet which is attached to the first support. In this way, a plurality of sheets can be attached to the supports 5 and fit together to form a continuous face surface 1 , 2.

Figure 4 shows a side view of a sheet 42 of GRC attached to one of the supports 5. As can be seen in this figure, the sheet has widened regions 43, 44 at its upper and lower ends, with a narrower region 45 therebetween. The narrower region 45 is, in this example, formed by a recess on the inner side of the sheet 42, i.e. the side facing the support 5, so the outer-facing side 46 of the sheet 42 is planar, or substantially planar.

On its upper and lower edges 47, 48, the sheet 42 has connection apertures 49. Each connection aperture 49 comprises a bore, lined with a sturdy material such as steel, with an anchor 50 (which may take the form of a pin) protruding from the bore into the interior of the sheet 42 by a short distance. Any number of connection apertures 49 may be formed along the upper and lower edges 47, 48 of the sheet 42, but in some embodiments only one connection aperture 49 is formed on each of the upper and lower edges 47, 48.

Support arms 51 protrude outwardly from the support 5, and include upward- facing and downward-facing connection protrusions 52 which are adapted to fit into the connection apertures 49. The connection protrusions 52 may, for example, take the form of pins, formed from a robust material such as steel.

As the skilled reader will appreciate, the sheet 42 may be fixed readily in place with respect to the support 5, by fitting the appropriate connection protrusions 52 into the connection apertures 49 on the upper and lower edges 47, 48 of the sheet. Further sheets may be installed above and below the sheet 42, in a similar manner, to form a face surface 1 , 2. The side view shown in figure 4 is taken through a vertical section. However, it should be understood that a view taken through a horizontal section may be generally identical, including widened sections at the edges of the sheet, connection apertures and support arms with connection protrusions, as shown in figure 4.

The sheet 42 is wider at its edges to provide a sufficient thickness to accommodate the connection apertures 49 and the associated anchors 50, and to provide sufficient strength at these locations, where the greatest forces are likely to be experienced. However, the sheet 42 is narrower in its central section to reduce weight and cost.

Where the edges of the sheets meet each other, a seal is preferably formed between the sheets, and for instance this may take the form of a silicone seal.

The supports 5 are preferably spaced apart by a distance which is equal or substantially equal to the width of each sheet. This allows adjacent vertical sets of sheets to be attached to adjacent supports 5, as the skilled reader will understand.

The above discussion primarily relates to an unbroken region of a straight wall, formed from sheets of GRC which are of regular and consistent sizes and shapes. However, sheets will sometimes need to be used which are of irregular or different sizes, for instance where walls meet each other, around windows, alcoves or partitions, or where the height of a wall is not equal to the combined heights of an exact number of regular sheets. For these purposes, sheets of different shapes and sizes may be created, as the skilled person will readily understand.

Sheets of GRC may also need to be formed which extend in more than one plane, for instance where an internal wall meets a window aperture. Sheets may need to be produced which have a first portion set at a first angle (e.g. the part of the sheet corresponding to a region of an inward-facing wall), and a second portion at a second angle (e.g. corresponding to a region of the window aperture), where the first and second portions may be at 90° to each other. Sheets of GRC can readily be produced which have shapes of this nature. Figure 5 shows a cross-sectional view through first and second face surfaces 1 , 2, taken at a position between supports 5. In the example shown in figure 5, a water pipe 7 is shown between the face surfaces 1 , 2. An electrical cable 8 also extends up from ground level 4 between the face surfaces 1 , 2, and is diverted to one of the face surfaces 1 at an appropriate height for a plug socket (not shown). Apertures may be cut in one or both of the first and second face surfaces 1 , 2 to allow services within the wall to communicate with the outside of the wall. For instance, apertures may be cut for plug sockets, taps, light fittings, data ports, ventilation, and so on.

In a next step, shown in figure 6 a cellular lightweight concrete (CLC) 9, which is initially in a liquid form, is poured into the gap 3 between the face surfaces 1 , 2, to fill this gap 3 up to a certain height. In the example shown in figure 6, the CLC 9 is poured into the gap to fill the gap up to the level of the tops 6 of the face surfaces 1 , 2.

As the skilled reader will understand, CLC is a type of concrete which includes a foaming agent, to result in a finished material having air bubbles which displace at least some of the concrete, leading to a material which is less dense and more easy to work with than regular concrete.

In preferred embodiments, a low-density CLC is used. Preferably, the density of the CLC is below 250 kg/m ³ . The density of the CLC is preferably between 70 and 250 kg/m ³ , and more preferably between 100 and 200 kg/m ³ . In some preferred embodiments of the invention the density of the CLC used is around, or exactly, 150 kg/m ³ .

A CLC having a density of 150 kg/m ³ can be formed by mixing 150kg of cement, 62kg of water, and 890I of a foam. For these purposes it is preferred to use a foam which is available, under the name N-600, from Neopor (a division of BASF) or through worldwide agencies of Neopor. This foam may also be obtained from PBP Berlani Holding Ltd. (contactable at 3rd Floor, 120 Baker Street, London W1 U 6TU, United Kingdom, on + 41 79 66 30 428 or at www.pbpberlani.com).

In a preferred method of formulating the CLC, the mortar consists of Portland cement Type 1 and water. This must be mixed for a minimum of 30 seconds. When the mortar is ready, the foam is added in it. The foam must be stable and the bulk density of the foam should be between 60g and 80g per litre. Stable foam can be made with a Neopor Plug & Foam unit. Towards the end of the process, the foam must be mixed homogeneously into the mortar. The mixing of foam into the mortar takes place in a mixer, resulting in a very light CLC which is suitable for use with the present invention. Suitable machines for the production of the CLC can be obtained from PBP Berlani Holding Ltd.

By way of example, in order to increase the density of the CLC, more cement and water can be included in the mixture. A volumetric calculation can be used. For instance, if a further 50kg of cement is included in the example mixture given above, this contributes around a further 161 of volume to the mixture. If another 11 of water is added, this gives a total of 171 extra volume that is added to the mixture. To compensate for this, 171 less of foam should be added. The mixing process will remain as explained above.

Conversely, to reduce the density of the mixture, less cement and water can be included, and the skilled person will realise how this can be achieved.

It is not necessary to use a volumetric approach, and the above are given only as examples.

Once the CLC 9 has set, the resulting wall 10 is finished or substantially finished. It is important to note that the face surfaces 1 , 2 are not removed once the CLC 9 has set, and the face surfaces 1 , 2, the CLC 9 and the supports 5 all form part of the finished wall 10.

It is mentioned above that apertures are formed in the first and/or second face surfaces 1 , 2 to allow services to communicate with the exterior of the wall. These apertures are preferably formed before the pouring of the CLC.

A wall having a construction of this type may have considerable advantages with respect to conventional insulating walls. The combination of glass fibre reinforced board and CLC will provide a very high level of thermal insulation. The low viscosity of low-density CLC will ensure that the CLC completely fills the gap 3 between the face surfaces 1 , 2, including any small irregular volumes which are formed against or around the face surfaces 1 , 2 or any components which are positioned between these face surfaces 1 , 2. As can be seen in figure 4, a gap preferably exists between each support 5 and the inner side of each face surface 1 , 2, and this also allows the CLC to flow past each support 5 to fill the space between the face surfaces 1 , 2. The narrower, recessed regions of the sheets 42 also allow space for the CLC to flow past the supports 5. However, it is also preferred that the support structure includes a series of spaced apart support elements having opposite sides, with one face surface 1 being attached to one of the sides, and the other face surface 2 being attached to the other of the sides. It is preferred that the width of each of the support elements is substantially the same as, or slightly less than, the distance between the inner sides of the two face surfaces 1 , 2.

In addition to this, the shape/volume or insulating properties of the CLC will not appreciably deteriorate over time, and the performance of the resulting wall 10 will therefore remain consistent over the life of the structure of which the wall 10 forms a part.

It is important to note that, in the example of the wall 10 given above, the CLC

9 acts as an insulating material, rather than as a structural or supporting material. In conventional concrete structures, a volume is defined between (for example), sheets of plywood, and concrete (having a relatively high density) is poured between the sheets to form a wall. After the concrete has set, the sheets of plywood are removed to leave the finished wall as a structural or supporting element.

By contrast, in embodiments of the invention the structural rigidity of the wall

10 is provided primarily by the support structure, which is positioned between the face surfaces 1 , 2. The face surfaces 1 , 2 remain in place as part of the completed wall 10, and provide additional thermal and/or sound insulation, as well as providing an attractive and presentable face on either side of the wall 10.

The sides of the face surfaces 1 , 2 that face outwardly from the wall 10, i.e. that are visible once the wall 10 has been constructed, can be moulded or otherwise worked to have any suitable pattern or configuration.

These surfaces can be formed to be smooth and relatively featureless. Alternatively, the surfaces can be moulded to have an appearance akin to brickwork or stonework, or any other desired pattern, texture or appearance. This provides a high degree of flexibility to users regarding the appearance of the finished wall.

This may be of particular utility when one or more of the surfaces of the wall 10 will be on the exterior of a structure. Patterns resembling brickwork or stonework, for example, may be particularly desired in these instances. In the example below the appearance of brickwork is used, but it should be understood that any other desired pattern, texture or appearance could also be used.

An example of a GRC sheet 35 which may be used for the first (i.e. external) face surface 1 is shown in figure 7. The sheet 35 is formed to resemble a section of conventional brickwork. The sheet 35 has generally straight top and bottom edges 36, 37, and castellated left and right edges 38, 39. The sheet 35 has divisions 40 formed thereon to resemble cement layers, so that the regions 41 between the divisions 40 have the appearance of a series (in the example shown, five rows of four) of bricks. The sheet 35 may be sprayed, painted or otherwise coloured to resemble brickwork more closely. A sheet of this kind has the advantage that the castellated left and right edges 38, 39 will fit together neatly, and help to ensure that adjacent sheets are correctly aligned with each other. The serpentine join between adjacent sheets will also help to avoid having a straight vertical join, which would be more visible.

Sheets for use on the second (i.e. inner) face surface 2 may be generally square or rectangular. The appearance of brickwork or other textured surfaces on internal walls will be less commonly desired (although this may be appropriate for“loft” type interior decoration), and vertical joins between sheets are unlikely to be visible as internal walls will be covered with render, wallpaper or another covering as part of the decoration/fit out process.

Walls formed in the manner described above will be less prone to vibration than conventional walls. Because the low viscosity CLC will substantially fill the entire space between the face surfaces 1 , 2, the finished structure will be solid and continuous, and resistant to vibration, or the transmission of vibration. The combination of glass fibre reinforced board (particularly GRC) and CLC also provides advantageous protection against corrosion, and has advantageous fire resistant properties. Referring to figure 8, a further aspect of the invention is shown.

Figure 8 shows a pair of spaced apart walls 11 , 12, each comprising (as discussed above) first and second face surfaces 1 , 2 formed from glass fibre reinforced board. Support structures (such as series of supports 5 of the type shown in figure 1 ) are positioned respectively within the two walls 11 , 12. In this example the support structure extends vertically above the level of the inner (second) face surface 2. Additional components such as water pipes, electrical cables and so on may be included within these walls 11 , 12, as required, but are not shown in figure 7.

Between the top edges 14 of the inwardly-directed face surfaces 1 , 2 of the two walls 11 , 12 is a ceiling surface 15, which is once again formed from glass fibre reinforced board. The ceiling surface 15 is joined to the top edges 14 of the inwardly-directed face surfaces 1 , 2. As the skilled reader will understand, the ceiling surface 15 may be formed from a series of contiguous sheets of GRC, which are attached to the undersides of a series of horizontal support elements fixed in place above the ceiling surface 15, in a similar manner to the way in which the face surfaces 1 , 2 are formed. Above the level of the ceiling surface 15 a horizontal or substantially horizontal support element (not shown), forming part of the support structure, is positioned and connected to the components of the support structure that extend within the walls 11 , 12. It will be understood that this formation of face surfaces 1 , 2 and the ceiling surface 15 provides a continuous internal space, extending between the face surfaces 1 , 2 of each wall 11 ,12, and above the ceiling surface 15. This internal space is enclosed or substantially enclosed on all sides, except on its top (i.e. upward-facing side).

Once these components are in place CLC 17 is poured into this internal space, so that the CLC 17 fills the spaces between the face surfaces 1 , 2 of the first and second walls 11 , 12 and is filled up to a level above that of the ceiling surface 15, so that the CLC 17 completely covers the ceiling surface 15 to a certain depth. In the example shown, this depth rises above the level of the horizontal support element, although this is not essential.

Once the CLC 17 has set, it will be understood that a continuous, unitary and unbroken volume of CLC 17 is formed, extending within both walls 1 1 , 12 and above the ceiling surface 15.

Using this technique, both the walls and the ceiling of a storey of a building structure can be formed in one step. This has several advantages over existing building methods.

Firstly, stories of a building can be constructed quickly. The face surfaces 1 , 2 and ceiling surface 15 can be formed either resting on a ground level, or (if one or more storey has already been completed) on top of an existing, completed storey. CLC can be poured into the resulting space in one step, filling the space to a depth which forms the entire height of the walls and also at least part of the ceiling. Once the CLC has set, the storey is effectively completed. As discussed above, there is no need to remove any of the face surfaces 1 , 2 or the ceiling surface 15.

With regard to thermal and sound insulation, the fact that the CLC forms a continuous, unitary and unbroken structure extending through the walls and ceiling means that there are no gaps, breaks or joints which may transmit heat or noise.

The formation of a storey in this way, including walls and a ceiling, may include a complex and/or irregular shape including both internal and external walls, and other features such as partitions, internal arches and so on. It is anticipated that, where a storey is formed in a single stage in the manner described above, external walls will have a greater thickness than internal walls, as external walls are likely to have a requirement for greater thermal and noise insulation. This will be discussed in more detail below.

Particularly for a larger structure, the volume of CLC required to form a storey in a single stage may be very large. Where it is not possible or practical to provide a sufficient quantity of liquid CLC to form the entire storey in one stage, the storey may be formed in two or more operations. However, it is preferred that, in situations such as this, the storey is divided into two or more sections, each of which includes walls and a connected region of ceiling. In practice, a first section will be prepared and filled with CLC so that the walls and ceiling are formed in one operation. Once this has been completed, CLC will (at a later time) be poured into a further section, once again filling the walls and ceiling in one operation. Further sections may then be completed as necessary.

It should be understood that, where a storey is completed in two or more operations, this is preferably not done by pouring CLC to fill the whole or part of the storey up to a first height, allowing the CLC to set, and subsequently pouring further CLC to fill the storey up to the level of the ceiling.

Figure 9 shows in greater detail a junction between a wall of a first, lower storey, a ceiling of the first storey, and the wall of a second, immediately higher storey. First and second face surfaces 1 , 2 are provided as part of the first wall 18, which is a wall of a first, lower storey. As discussed above, this lower storey may be a ground-floor storey, or may be a higher-level storey which is built on one or more existing stories. The inner face surface 2 terminates at a top edge 14, and is joined at this top edge 14 to a generally horizontal ceiling surface 15, as described above.

The outer face surface 1 rises above the level of the top edge 14 of the inner face surface 2. In this embodiment, the outer face surface 1 rises continually to form part of an upper wall, as described in more detail below.

A beam 19, which forms part of a support structure, is shown above the ceiling surface 15, and it should be understood that this beam 19 will be connected to other structural elements to form the support structure.

Low-density CLC 17 is poured into the space created by the first and second face surfaces 1 , 2 and the ceiling surface 15, to fill entirely the space between the first and second face surfaces 1 , 2 and cover the ceiling surface 15 to a set depth. In the embodiment shown this depth is 200mm, but any other suitable depth may be used.

The CLC 17 is allowed to set. As will be understood from the discussion above, the first and second face surfaces 1 , 2 and the ceiling surface 15 remain in place, and will form part of the finished structure. In the embodiment shown, a layer of wire mesh 16 is positioned above the level of the CLC 17. In the example shown in figure 4 the wire mesh 16 is positioned on top of the beam 19. The wire mesh 16 extends in a plane (in the view shown in figure 4, perpendicular to the plane of the paper) and in preferred embodiments will rest on further beams (not shown) and/or other supporting members.

An inner face surface 20 for the wall 21 of the second, upper storey is placed in position. Preferably, and as shown in figure 4, the inner face surface 20 of the upper wall 21 is generally co-planar with the inner face surface 2 of the lower wall 18. The lower edge 22 of the inner face surface 20 of the upper wall 21 preferably lies above the level of the CLC 17. This inner face surface 20 may be supported in position by any suitable supports or restraints (not shown).

A top layer 23, which preferably comprises cement, is then poured on top of the CLC 17, to form a further layer which is above the CLC 17. In preferred embodiments the depth of this top layer 23 is less than the depth that the CLC 17 extends above the ceiling surface 15, and in the embodiment shown this depth is 5mm. The invention is not limited to this, however.

On top of the top layer 23, a layer of a finishing surface 24, such as tiles or carpet, is placed. The floor 25 of the upper storey is then complete and ready for use.

As will be seen from figure 8, when the top layer 23 is poured onto the CLC 17, this layer does not enter the space 26 between the inner and outer face surfaces 1 , 20 of the upper storey wall 21. In order to ensure that this does not occur, a surface or other blocking element (not shown) may be placed across the lower edges of the inner and outer face surfaces 1 , 20.

As a next step, further CLC 17 is poured into the space between the inner and outer face surfaces 1 , 20 of the upper storey, to form the wall 21 of the upper storey. As the skilled reader will appreciate, at the upper end of this wall 21 (not shown), a further ceiling may be formed in one operation, as has been described above.

In the embodiment shown a bracing arrangement is provided to help maintain the correct alignment, and/or spacing between the various components during the construction process. First and second anchoring angles are positioned within the lower and upper walls 18, 21 , and may be held in place by any suitable means before the CLC 17 is poured. The first anchoring angle 27 is provided at the top of the first (lower) wall 18, and the second anchoring angle 28 is provided at the bottom of the second (upper) wall 21.

A bolt 29 extends between the anchoring angles 27, 28, and is secured thereto by respective nuts 30.

A series of screws 31 pass through the anchoring angle and may be used to secure the anchoring angles 27, 28 to one or more components (not shown) of the support structure. In the discussion above, the walls and ceiling of a storey are formed in one operation. However, in alternative embodiments of the invention, the walls and floor of a storey may be formed in one operation, and this is also encompassed within the scope of the invention. The skilled reader will appreciate how the steps set out above may be varied in order to form the floor and walls of a storey in one operation.

The discussion above states that all or most of the components of the support structure may be formed from light gauge steel. However, where a structure formed in accordance with the invention comprises several stories, some of the components of the support structure may be reinforced by, or formed entirely from, heavier gauge steel, or one or more other materials.

In implementation of the invention it is anticipated that a large proportion of the construction work can be carried out on-site, with components of the support structure and panels of glass fibre reinforced board being produced on-site, and CLC of an appropriate type also being mixed to order on-site. This will allow greater efficiency and speed, and involve less environmental damage, than the fabrication of whole walls or other building portions at a dedicated facility, which are then transported to a site to be assembled into a finished building structure.

Aspects of the present invention also relate to the planning of building structures. In particular, the thickness of one or more walls of a proposed structure can be determined, prior to construction of the wall, based on a desired level of thermal and/or noise insulation. These levels may be set by legislation in one or more countries, or may be specified by a client for whom a building is being constructed.

Where a wall is constructed of various layers, the thermal conductivity (also known as the K-value) of each material will be known. From this the material’s R-value can be also be calculated - the R-value is a measure of a material’s capacity to resist heat flow from one side of a layer of the material to the other.

By considering each of the layers that make up a wall, and the thicknesses of these layers, the overall U-value of the wall can be calculated. The U-value of a wall (or other building component, such as a ceiling, roof or floor) is a metric of the amount of heat energy that is transmitted through a square metre of the wall for every degree of difference in temperature between the inside and outside of the wall. U-values are typically expressed in W/m ² K.

An example of a U-value calculation for an external wall comprising CLC between two boards of GRC is shown below:

Here the inner and outer skin coefficients will be determined by properties of the inner and outer faces of the wall, and will be influenced by which paint etc. is used, as will be understood by the skilled reader. A further example of a U-value calculation is given below for a floor, which comprises a ceiling layer formed of GRC board, with 0.2m layer of low-density CLC formed above the ceiling layer, and a 0.1 m layer of higher-density CLC formed on top of this. A thin layer of screed is formed on top of the high- density CLC.

Based on these calculations, the U-value of a wall having a certain proposed construction can be compared to the U-value that is required, either by legislation or by a client’s preference. This method can, of course, be used to check that a proposed building structure will meet any set of given requirements.

However, the design of a wall (for example) may also be planned or altered based on a desired U-value. For instance, the desired U-value may be stated, and thickness of the CLC layer (which is the parameter of the wall which is most easy to vary) may then be set so that the overall U-value of the wall is equal to the desired U-value, or exceeds the desired U-value by a predetermined margin or factor (for instance, by 10%).

In aspects of the invention, a storey of a structure is formed in a single operation, as discussed above. The story may include several surfaces which are formed as part of this operation, for instance a series of external walls, a series of internal walls, and a ceiling surface. Each of these will have a minimum U-value.

As discussed above, the same CLC will be used to form all of these various surfaces. In an aspect of the invention, the thickness of the CLC will be used to determine the thickness of each of the surfaces, so that each surface meets (or exceeds, as discussed above, by a set margin or proportion) the required U-value. In this way, the thermal properties of the layers of each surface, including particularly the CLC, is used to determine the thickness of the layer of CLC within each surface.

In general, an external wall will have a higher required U-value than an internal wall. Where the same CLC is used to form an entire storey in one operation, the external walls will therefore likely be thicker than the internal walls, so that use of the same CLC results in the external and internal walls all fulfilling their U-value requirements.

In certain embodiments the thickness of each surface formed during the formation of a storey may have at least the thickness required to give it the desired U-value.

This technique is in contrast with conventional building approaches where an external wall may be formed from different materials compared to, for example, an internal wall. Forming all of the major components of a storey of a structure in a single operation, using substantially the same materials, and varying the thicknesses of the CLC layers within the various components, allows a storey to be formed in a rapid and convenient way, with all of the components fulfilling their requirements for thermal insulation. In a further aspect of the invention, the thickness of at least one component that will be formed during the formation of a storey of a structure, such as an external wall, may be pre-determ ined by other factors or considerations, or may only fall within a certain constrained range. In this case, the density of the CLC that is used to form the wall may be varied in order to achieve the desired U-value. As the skilled reader will be aware, the thermal conductivity of CLC will be related to its density - the higher the density, the lower the thermal conductivity. If a first density of CLC (for instance, 150 kg/m ³ ), used within the set thickness for the external wall, does not give the desired U-value, the density of the CLC may be increased (for instance to 175 kg/m ³ , or 200 kg/m ³ ) so that the wall provides the desired U-value.

Once the density of CLC has been chosen, in preferred embodiments of the invention the same density of CLC is used throughout the storey of the structure when it is formed. This has the advantage of retaining the simplicity, discussed above, of forming all of the major components of a storey of a structure in one operation.

Some aspects of the invention may be provided to be compatible with a BIM (building information modelling) platform, as will be understood by those skilled in the art, although this is not essential.

In preferred embodiments of the invention, where a multi-storey structure is created using techniques embodying the present invention, a different density of CLC may be used in different floors of the structure. This may be because, in certain floors, there are factors which constrain the thickness of certain surfaces. Alternatively, the U-value requirements for different floors may vary.

The invention provides robust and flexible methods for rapid, efficient and cost-effective formation of building structures.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.