Technical Field of the invention

The present disclosure generally relates to a fibre cement plate used in a wall structure. Furthermore, the disclosure relates to a wall structure formed by assembling fibre cement plates having cooperating elongated projections and elongated grooves arranged along adjoining edges. Such plates are often called plates with “tongue and groove” connections.

Background of the invention

When making a wall structure with fibre cement plates, it is typical to create a rear structure having vertical wooden beams and horizontal wooden cross beams connecting the vertical beams. The fibre cement plates are then mounted on the underlying wooden structure. The fibre cement plates are arranged in the way that all edges, both vertical and horizontal, of each fibre cement plate are supported by the vertical and horizontal wooden beams via screws along the edges of the plates. In this way, the adjoining edges between two adjacent fibre cement plates are supported by a wooden beam arranged behind the plate. The wooden beams are necessary to support the edges of the plate to provide strength to the wall. Furthermore, over time the two adjoining edges will pull slightly apart due to material dimensional changes, and a gap could be formed between the two adjoining edges. In order to ensure a fire-proof covering, the wooden beams behind the plates will ensure that this gap is covered. If the gap were open, then flames could pass through the wall structure via the gap. In certain cases, in the prior art, instead of a rear wooden beam arranged between the horizontal edges of adjoining plates, it is possible to use a galvanized steel H beam to seal and support the edges of two adjoining plates. Other forms of arrangements are also known in the art to support/seal the edges of adjoining plates. The known prior art types of wall structure are however complicated to build as they requires both vertical wooden beams and horizontal wooden or steel beams. Furthermore, due to the use of screws to mount the plates to the underlying support structure, mounting is time consuming and many screws are needed. Also, the vertical and horizontal beams need to be placed precisely so that the edges of the fibre cement plates are properly supported.

Moreover, in the prior art, the fibre cement plates are large which means that they are heavy and in general too large for a single worker to carry safely. In many cases, the plates are so heavy that even two workers should not carry them by themselves and mechanical lifting equipment needs to be used. However, due to bad work place habits, workers sometimes do carry single plates by themselves. This causes physical stress to the workers and long term wear which causes sick leave.

Furthermore, it is often desired to make the wall structure windproof and waterproof. This is currently done by additionally applying a waterproofing tape to the joins between all adjoining plates on the outwards facing, or weather exposed, side after mounting all the plates on the rear beams.

It should also be noted that in certain cases, such wall structures are assembled on a building as a final external wall structure. In other cases, such wall structures are assembled initially as an external wall structure, but are covered by a more permanent wall structure later on. For example, a fibre cement wall structure is assembled first and then later on, a brick outer surface is erected to cover the fibre cement wall structure. However, depending on the construction process, many months can elapse between erecting the fibre cement wall structure and covering it with a more permanent wall structure. In the period prior to erecting the final external wall structure, the fibre cement wall structure must be windproof and waterproof. It can also be noted that different forms of fibre cement plates with different forms of cooperating elongated projections and grooves which engage with each other are known in the art. Such plates are often used for flooring and/or interior walls where there are low requirements for strength, fire protection and/or moisture/weather proofing. An example of such a plate is disclosed in US2020157812. The form of the projection and groove in this prior art type plate is not suitable for use where there are cooperating projections and grooves along all four sides of a plate. This type of prior art type plate is more designed to mechanically lock two plates together and requires a pivoting of the plate about a vertical axis to engage the plate with another plate. This is only suitable when only one edge is to be locked at a time.

Summary of the invention

A first aspect of the current invention is to provide fibre cement plates for a wall structure having elongated projections and grooves along the edges of the plate to facilitate an assembly of the fibre cement plates with each other without requiring a plurality of horizontally and/or vertically oriented beams arranged behind each join between two adjoining plates.

A second aspect of the current invention is to provide a wall structure having a plurality of fibre cement plates engaged with each other via elongated projections and grooves, thereby eliminating a need of horizontally oriented beams to support the fibre cement plates.

A third aspect of the current invention is to provide a fibre cement plate which does not need waterproofing tape to prevent ingress of water into the wall structure through the joints between two adjacent plates.

These aspects are provided at least in part by a fibre cement plate according to claim 1 . According to claim 1 , the fibre cement plate includes a rectangular body having a top edge and a bottom edge arranged spaced apart and substantially parallel to each other, first and second lateral edges arranged spaced apart and substantially perpendicularly to the top and bottom edges and inwards and outwards facing surfaces. Further, the first and second lateral edges are disposed substantially parallel to each other and connect the top and bottom edges. Moreover, the bottom edge is provided with an elongated groove and the top edge is provided with an elongated projection adapted to be inserted inside an elongated groove of bottom edge of an adjacent identical fibre cement plate. Also, the first lateral edge is provided with an elongated groove and the second lateral edge is provided with an elongated projection adapted for insertion inside an elongated groove of a lateral edge of an adjacent identical fibre cement plate. Moreover, a sealant is provided in the elongated groove of the first lateral edge.

It should be noted that the term “elongated projection” should be understood as a projection which runs along an edge of a plate in an elongated manner. Likewise the term “elongated groove” should be understood as a groove which runs along an edge of a plate.

It should also be noted that while the plate is not a part of a wall structure, the inwards and outwards facing surfaces could be interpreted as first and second surfaces, since the terms inwards and outwards are first limiting when the plate becomes part of a wall structure.

Again, as discussed above, when the plate is not a part of a wall structure, the top and bottom edges, could be considered first and second edges. The terms top and bottom are first really limiting when the plate becomes a part of a wall structure. However, the terms top and bottom edge make the claims more clear to the person skilled in the art. In one embodiment, the sealant is provided in the elongated groove of the first lateral edge only and the elongated groove of the bottom edge is devoid of the sealant.

In one embodiment, the sealant includes a peel off strip that is removed before installing the fibre cement plate.

In one embodiment, the sealant is in the form of a paste and is essentially non-curing during the sealant lifetime and retains adhesiveness and elasticity during the sealant lifetime.

In some embodiments, the sealant is arranged at a base or the bottom of the elongated groove. In some embodiments, the elongated groove of a first lateral edge, the elongated projection of a second lateral edge and the placement of the sealant in the elongated groove are arranged such when an elongated projection of a second lateral edge of one plate is inserted into an elongated groove of a first lateral edge of an adjacent plate, the tip of the projection engages the sealant. In some embodiments, the tip of the projection engages the sealant such that sealant wraps around the tip of the projection. In some embodiments, after the tip of the projection has engaged the sealant, the sealant is arranged on both the outside facing side and the inside facing side of the projection.

In some embodiments, the sealant is arranged closer to the outwards facing surface of the plate than the inwards facing surface of the plate. In some embodiments, at least a portion of the sealant is arranged at a location in the elongated groove which is between the base of the groove and the outwards facing surface of the plate. In this way, water ingress into the vertical groove will be stopped before reaching the base of the groove. In some embodiments, at least a portion of the sealant is arranged at a location in the elongated groove which is between a plane connecting the base of the elongated groove along the bottom edge and the tip of the elongated projection of the top edge of the plate and the outwards facing surface of the plate. In this way, water ingress into the vertical groove will be stopped at a location which is outside the tip of the projection of the top edge of an adjacent plate when the plates are assembled into a wall structure, thereby ensuring that water ingress into the vertical grooves, will not run past the tip of the projection of the top edge of an adjacent plate.

In some embodiments, the elongated groove of a first lateral edge and the elongated projection of a second lateral edge are arranged such that an elongated projection of a second lateral edge of a first plate can be inserted into an elongated groove of a first lateral edge of a second plate adjacent to the first plate by motion along a direction which is parallel to the plane of the first and second plate.

In some embodiments, the elongated projection of the top edge and the elongated projection of the second lateral edge are identical. In some embodiments, the elongated groove of the bottom edge and the elongated groove of the first lateral edge are identical.

In one embodiment, the outwards facing surface is provided with a hydrophobic coating which reduces water ingress into the outwardly facing surface. In this way, the plate can be prevented from deforming over time when the outer surface is exposed to moisture. When one surface of a fibre cement plate becomes wetter than the other surface of the plate, then the plate could bend towards the wetter surface. For normal plates, this is okay since the plates are usually fastened to an underlying frame structure with a number of screws. In contrast with the current system, the bending should be reduced for certain forms of grooves and projections. Depending on the shape and form of the projection and groove, extensive bending of the plates could cause the projection and/or the groove to break, thereby reducing the strength of the joint between adjacent plates and/or reducing the water proofness of the wall structure provided by the plates.

In one embodiment, the hydrophobic coating is applied by a roller, by spraying, by dipping or by another suitable method. In one embodiment, the hydrophobic coating comprises any one of Silane, siloxane, silicone resins, metallic stearates, hydrophobic polymers or a combination of these. The specific amount of hydrophobic coating applied depends on the properties of the actual plate used. The amount should be enough to prevent unacceptable bending of the plate when exposed to moisture. However, in certain cases, the plates need to retain a certain amount of permeability for water vapour, i.e. the plate needs to remain “breathable”. A person skilled in the art of fibre cement plates will be able to provide a suitable coating in a suitable amount to provide the desired characteristics and to provide a suitable trade-off between breathability and waterproofness.

In one embodiment, the fibre cement plate is a part of a wall structure and the elongated groove and projections of the lateral edges are disposed vertically and the outwards facing surface is arranged further from a centre of the wall structure than the inwards facing surface. In some embodiments, the wall structure is arranged as an external wall structure. In some embodiments, the outwards facing surface of the fibre cement plate is arranged as a weather exposed surface.

In one embodiment, the fibre cement plate has a thickness of 9mm and includes an outwards facing surface having a length of 1500mm and a width of 600mm. In one embodiment, the fibre cement plate has elongated projections, which extends 1cm past the surface edge, so the overall length of the plate is 1510mm and the overall width of the plate is 610mm. Other dimensions are also possible, as discussed later on in this specification. In one embodiment, one or more dimensions of the fibre cement plate can change due to changes in ambient temperature and humidity and the sealant is adapted to stretch and/or compress to maintain the sealing between two connected fibre cement plates. In one embodiment, the sealant has adhesive properties, such that the adhesive forms an adhesive connection between the projection and groove of two adjacent plates. In one embodiment, the sealant’s adhesive properties have a high elasticity and a high elongation to break coefficient. In this way, the sealant will remain attached to the plates but will easily stretch when the plates change in dimension. In this way, the sealant does not contribute significantly to hold the plates together. This is in contrast to a more traditional adhesive where the purpose is joint strength to hold adjacent plates together. In one embodiment, the elongation at break coefficient is greater than 100%, greater than 200% or greater than 300%. In one embodiment, the strength of the adhesive is low. In one embodiment, the coefficient of strength of the adhesive is less than 1 MPa, less than 0.5 MPa or less than 0.25 MPa.

In one embodiment, the length of the fibre cement plate may decrease between 2 and 4 mm due to ambient temperature and humidity and the sealant is adapted to stretch to maintain the sealing contact between the adjacent plates.

According to an additional aspect of the present invention a wall structure is disclosed. The wall structure includes an array of vertically or horizontally extending support beams and a plurality of fibre cement plates attached to the beams and engaged with each other. Further, each fibre cement plate has a first and a second vertically oriented lateral edge, a first and a second horizontally oriented edge and an inwards and an outwards facing surface. In some embodiments, the wall structure is an external wall structure. In some embodiments, the outwards facing surfaces of the plurality of fibre cement plates are arranged as weather exposed surfaces.

The first horizontally oriented edge is provided with a longitudinal groove and the second horizontally oriented edge is provided with an elongated projection arranged inside an elongated groove of a first horizontally oriented edge of an adjacent identical fibre cement plate. Moreover, the first vertically oriented edge is provided with an elongated groove, the second vertically oriented edge is provided with an elongated projection arranged inside an elongated groove of a of a first vertically oriented edge of an adjacent fibre cement plate and a sealant is provided in the elongated groove of the first vertically oriented edge. In some embodiments, the sealant is provided at the base, or the bottom of the elongated groove of the first vertically oriented edge. In some embodiments, the sealant is wrapped around the tip of the elongated projection of the second vertically oriented edge which is arranged inside the elongated groove of the first vertically oriented edge of the adjacent fibre cement plate.

In some embodiments, at least a portion of the sealant is arranged closer to the outwards facing surface of the plate than the inwards facing surface of the plate. In some embodiments, at least a portion of the sealant is arranged at a location in the elongated groove which is between the base of the groove and the outwards facing surface of the plate. In this way, water ingress into the vertical groove will be stopped before reaching the base of the groove. In some embodiments, at least a portion of the sealant is arranged at a location in the elongated groove which is between a plane connecting the base of the elongated groove along the bottom edge and the tip of the elongated projection of the top edge of the plate and the outwards facing surface of the plate. In this way, water ingress into the vertical groove will be stopped at a location which is outside the tip of the projection of the top edge of an adjacent plate, thereby ensuring that water ingress into the vertical grooves, will not run past the tip of the projection of the top edge of an adjacent plate.

In one embodiment, the first horizontally oriented edge is a bottom edge of the fibre cement plate and the second horizontally oriented edge is a top edge of the fibre cement plate.

In one embodiment, the elongated groove of the first horizontally arranged edge each fibre cement plate is devoid of a sealant.

In one embodiment, the outwards facing surface of each fibre cement plate is provided with a hydrophobic coating which reduces water ingress into the surface.

In one embodiment, the plurality of fibre cement plates are arranged in a horizontally oriented staggered arrangement. In one embodiment, the vertically arranged edges of a lower plate are horizontally offset from the vertically arranged edges of an upper plate.

In one embodiment, the sealant includes a peel off strip that is removed before installing the fibre cement plate to the beams.

In one embodiment, the sealant is in the form of a paste and is non-curing during the sealant lifetime and retains adhesive and elasticity during the sealant lifetime.

In one embodiment, one or more dimensions of the fibre cement plates change due to changes in ambient temperature and humidity and the sealant is adapted to stretch and/compress to maintain the sealing between two connected fibre cement plates. In one embodiment, the length of the fibre cement plates may decrease at least 2mm, at least 3mm or at least 4mm due to ambient temperature and humidity and the sealant is adapted to stretch to maintain the sealing contact between the adjacent fibre cement plates.

According to yet another aspect, a method of forming a wall structure is provided. The method includes providing an array of vertically or horizontally extending support beams and providing a plurality of fibre cement plates. Each fibre cement plate including a top edge provided with an elongated projection, a bottom edge provided with an elongated groove, a first vertically oriented edge provided with an elongated groove, a second vertically oriented edge provided with an elongated projection and a sealant arranged inside the elongated groove of the first vertically oriented edge. The method also includes attaching a first fibre cement plate of the plurality of fibre cement plates to at least one of the support beams and engaging a second fibre cement plate of the plurality of the fibre cement plates with the first fibre cement plate by aligning a bottom edge of the second fibre cement plate with a bottom edge of the first fibre cement plate and sliding the second fibre cement plate in a horizontal direction to insert an elongated projection of the second vertically oriented edge of the first fibre cement plate or an elongated projection of the second vertically oriented edge of the second fibre cement plate into an elongated groove of the first vertically oriented edge of the second plate or an elongated groove of the first vertically oriented edge of the first fibre cement plate such that the sealant is squeezed.

In one embodiment, the method also includes engaging a third fibre cement plate of the plurality of fibre cement plates with the first fibre cement plate by sliding the third fibre cement plate in a vertically downward direction and fitting an elongated projection of the top edge of the first fibre cement plate into an elongated groove of the bottom edge of the third fibre cement plate. In one embodiment, the method also includes engaging a fourth fibre cement plate of the plurality of fibre cement plates with the first and/or second fibre cement plates by sliding the fourth fibre cement plate in a vertically downward direction and fitting an elongated projection of the top edge of the first and/or second fibre cement plate into an elongated groove of the bottom edge of the fourth fibre cement plate and then sliding the fourth fibre cement plate in a horizontal direction towards the third plate to insert an elongated projection of the second vertically oriented edge of the fourth fibre cement plate or an elongated projection of the second vertically oriented edge of the third fibre cement plate into an elongated groove of the first vertically oriented edge of the third plate or an elongated groove of the first vertically oriented edge of the fourth fibre cement plate such that the sealant is squeezed.

In one embodiment, the plurality of fibre cement plates are attached with the plurality of beams in a horizontally oriented staggered arrangement. In one embodiment, the plurality of fibre cement plates is arranged such that vertically oriented edges of an upper plate are horizontally offset from the vertically oriented edges of lower adjacent plates.

Brief description of the drawings

In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

Figure 1 shows a front view of a wall structure having an array of vertically extending beams and a plurality of fibre cement plates attached to the beams.

Figure 2 shows a sectional view of the wall structure taken along a sectional line ll-ll. Figure 3 shows a sectional view of the wall structure taken along a sectional line Ill-Ill.

Figure 4 shows an enlarged view of a portion of the section shown in FIG. 3 depicting an elongated lateral projection of a fibre cement plate arranged inside a lateral groove of an adjacent fibre cement plate.

Figure 5 shows an enlarged view of a portion of the section of the wall structure shown in FIG. 2 depicting an elongated longitudinal projection of a fibre cement plate arranged inside a longitudinal groove of an adjacent fibre cement plate.

Figure 6 shows the lateral groove and the elongated longitudinal projection of figure 4 apart from each other prior to assembly and depicts a sealant arranged inside the lateral groove.

Figure 7 shows the longitudinal groove and the elongated longitudinal projection of figure 5 apart from each other prior to assembly.

Figure 8 shows an enlarged view of a first embodiment of an elongated groove of one fibre cement plate and an elongated projection of another fibre cement plate with the sealant arranged inside the elongated groove prior to assembling the two plates.

Figure 9 shows an enlarged view of the embodiment of figure 8, but with the two plates assembled.

Figure 10 shows an enlarged view of a second embodiment of an elongated groove of one fibre cement plate and an elongated projection of another fibre cement plate with the sealant arranged inside the elongated groove. Figure 11 shows an enlarged view of the embodiment of figure 10, but with the two plates assembled.

Figures 12-15 shows various stages of assembling the fibre cement plates with the support beams to form a wall structure.

Detailed description of the embodiments

Referring to FIG. 1 , a wall structure 100 according to an embodiment of the disclosure is shown. The wall structure 100 includes a plurality of vertically extending support beams 102 and a plurality of fibre cement plates 104 attached to the beams 102 and engaged with each other. As shown, the beams 102 are arrayed in a horizontal direction and are arranged spaced apart from each other. In the embodiment, the lower ends 106 of the beams 102 are supported on a surface, for example, a ground surface, and abut the ground surface. In the embodiment, distances between any two adjacent beams 102 are equal. However, it may be appreciated that the distances between adjacent beams 102 may be different. Further, the beams 102 are shown and contemplated as wooden beams, however, it may be envisioned that the beams 102 may be made of any other suitable material, such as, but not limited to, steel, iron, etc.

The fibre cement plates 104 are arranged in a plurality of horizontally extending rows 110. The rows 110 are arrayed in the vertical direction along the lengths of the beams 102. As shown, the fibre cement plates 104 are arranged in a horizontally oriented staggered arrangement between different rows 110. The fibre cement plates 104 are similar in structure, and therefore, a structure and construction of a single fibre cement plate 104 is explained.

Referring to FIGS. 1 to 3, the fibre cement plate 104 (hereinafter simply referred to as plate 104) includes a rectangular body 112 having a front, or outwards facing, surface 114, a rear, or inwards facing, surface 116 arranged opposite to the front surface 114 and disposed facing the beams 102, and four edges: a first longitudinal, or bottom edge 120, a second longitudinal or top edge 122 disposed spaced apart and substantially parallel to the first longitudinal edge 120, a first lateral edge 124 connecting the first longitudinal edge 120 and the second longitudinal edge 122, and a second lateral edge 126 arranged spaced apart and substantially parallel to the first lateral edge 124 and also connecting the first and second longitudinal edges. As shown, the first lateral edge 124 and the second lateral 126 extend substantially perpendicularly to the first longitudinal edge 120 and the second longitudinal edge 122. In an assembly of the plate 104 with the beams 102, the first and second longitudinal edges 120, 122 extend horizontally and substantially parallel to the ground surface, while the first and second lateral edges 124, 126 extend in the vertical direction. As shown, the first longitudinal edge 120 of the plate 104 defines a bottom edge of the plate 104 and the second longitudinal edge 122 of the plate 104 defines a top edge of the plate 104.

Referring to FIG. 2 to 7, the top edge 122 includes an elongated projection 130 (best shown in FIGS. 5 and 7) extending outwardly from the body 112 and extending from the first lateral edge 124 to the second lateral edge 126, while the bottom edge 120 includes an elongated groove 132 (best shown in FIGS. 5 and 7) extending inside the body 112. The elongated groove 132 also extends from the first lateral edge 124 to the second lateral edge 126. In the embodiment, the elongated projection 130 is a tongue having a narrow top portion 134 and a wider lower portion 136. Similarly, the elongated groove includes a narrow base portion 138 to accommodate a narrow top portion 134 of an elongated projection 130 of an adjacent plate 104, and a wider upper portion 139 to accommodate a wider lower portion 136 of the elongated projection 130 of the adjacent plate 104. The specific dimensions and design of the tongue and groove embodiment shown in figures 2-7 are just shown schematically whereas the design and dimensions of the tongue and groove embodiments shown in figures 8-11 are more realistic.

Similarly, the first lateral edge 124 includes an elongated groove 140 (best shown in FIGS. 4, 6, 8, 9, 10 and 11 ) extending inside the body 112 and towards the second lateral edge 126, and the second lateral edge 126 includes an elongated projection 142 (best shown in FIGS. 4, 6, 8, 9, 10 and 11 ) extending outwardly of the body 112 in a direction away from the first lateral edge 124. Both the elongated groove 140 and the elongated projections 142 of the lateral edges extend along the vertical direction when assembled or attached to the beams 102. Also, the elongated groove 140 and the elongated projection 142 of the lateral edges extend from the first longitudinal edge 120 to the second longitudinal edge 122. As with the elongated groove 132 of the longitudinal edge, the elongated groove 140 of the lateral edge includes a narrow inner portion 144 and a wider outer portion 146. Similarly, the elongated projection 142 of the lateral edge includes a narrower outer portion 148 adapted to be inserted inside a narrower inner portion 144 of an elongated groove 140 of the lateral edge of an adjacent plate 104 arranged in the same row, and a wider inner portion 150 adapted to be arranged inside a wider inner portion 146 of the elongated groove 140 of the lateral edge of the adjacent plate 104. It should be noted that “inner” and “outer” refer to the centre of the plate where inner is closer to the centre of the plate and outer is farther away from the centre of the plate.

Additionally, the fibre cement plate 104 includes a sealant 160 (best shown in FIGS. 6, 8, 9, 10 and 11 ) arranged at a base of the elongated groove 140 of the lateral edge. The sealant 160 is adapted to prevent a passage of water or wind inside the wall structure 100 from the outside through a vertical joint defined between the elongated grooves 140 and the elongated projections 142 of the lateral edges of adjacently arranged plates 104. In an embodiment, the sealant 160 retains some of its elasticity and adhesiveness over time. Accordingly, the sealant 160 is applied to the elongated groove 140 of the lateral edge of the plate 104 in the factory prior to being shipped to the building site. In an embodiment, the sealant 160 is in the form of a paste which is non-curing throughout its lifetime. Accordingly, the sealant 160 retains its properties of elasticity and adhesiveness. In some embodiments, the sealant 160 is of the kind which is activated when squeezed. Therefore, the sealant 160 will not adhere to any dust/dirt present during shipping and storage and will first really become adhesive when exposed to a squeezing action during assembly.

In some embodiments, around 10% of the sealant 160 may be a combination of polyisobutylene and ethylene propylene diene monomer (EPDM) to ensure that the sealant 160 stays un-cured, tacky/adhesive and very elastic. The large elasticity of the sealant 160 makes it possible for the sealant 160 to compensate for movements (up to 2,4 mm/m) of the installed fibre cement plates 104 caused by rain, heat, and other weather implications.

In another embodiment (not shown), a thin outer “skin” or membrane forms on an outer surface of the sealant 160 after the sealant is applied to the elongated groove 140. However, the sealant 160 remains soft inside the membrane. The outer membrane of the sealant 160 repels dust/dirt during shipping and storage. The outer membrane ruptures when the elongated projection 142 is inserted inside the elongated groove 140, releasing the soft sealant material. In this manner, the sealant 160 retains its elasticity and adhesiveness.

In another embodiment, a peel off strip (not shown) may be provided on the surface of the sealant 160. The peel off strip is removed at the building site prior to installation or attachment of the fibre cement plate 104 with the beam 102. The peel off strip can keep the sealant 160 soft and elastic and free of dirt/dust, etc. In the embodiments shown in figures 1-7 and 12-15, the elongated projection 142 and the elongated groove 140 fit perfectly together. However, in another embodiment, shown in figures 8 and 9, the height of the projection 142 is smaller than the depth of the groove 140. In this way, there is more room for the sealant 140 to spread out in the groove when the projection is pressed into the sealant.

In another embodiment shown in figures 10 and 11 , the inner portion 150 of the elongated projection 142 can be arranged to fit snugly with the outer portion 146 of the elongated groove 140, but the outer portion 148 of the elongated projection 142 can be narrower than the inner portion 144 of the elongated groove 140. Then the narrow outer portion 148 of the elongated projection 142 can be pressed into the sealant 160 and there is room in the inner portion 144 of the elongated groove 140 to seal the elongated projection 142 properly. From the figures, it can be seen that the sealant wraps around the tip of the projection to form an effective seal. In this case, a portion of the sealant will be arranged on the inside facing surface of the projection and a portion of the sealant will be arranged on the outside facing surface of the projection. At the same time, the outer portion of the groove and the inner portion of the projection fit together snugly to provide a good fixation of the edges of the plates.

Although the elongated groove 132 of the bottom edge is shown to be devoid of a sealant, it may be appreciated that a sealant similar or even identical to the sealant 160 may be arranged at the bottom of the elongated groove 132 of the bottom edge.

In the current embodiment, a hydrophobic coating comprising a combination of silane, siloxane and acrylic binder is applied to the outwards facing surface of the plate via a roller at the factory. The coating will prevent the outwards facing, or weather facing, surface of the plate from absorbing excessive moisture. This will reduce undesired bending of the plate when the plate is exposed to moisture, as will be the case when the wall structure is an external wall structure.

It should be noted that the hydrophobic coating is necessary in certain cases, but could be less necessary in other cases. For example, for plates which are used in a drier environment, the hydrophobic coating could be avoided. Likewise, depending on the shape and arrangement of the elongated groove and elongated projection of the plates, the bending of the plates could be more or less relevant for the integrity of the wall structure comprising the plates. For example, in certain groove/projection designs, a plate without a hydrophobic coating will bend so much when exposed to moisture, that the groove and/or the projection could become damaged over time which would affect the structural strength and weather resistance of the wall covering. However, for other designs, the bending of the plate could have a less damaging effect on the groove/projection. In these cases, a hydrophobic coating could be avoided.

An embodiment of a method for forming the wall structure 100 according to the invention is now explained. The method includes providing an array of vertically extending beams 102. The beams 102 are provided such that the beams 102 are arrayed in a horizontal direction and are arranged spaced apart from each other. Further, each beam 102 extends in a vertical direction. Also, the beams 102 are positioned such that the lower ends 106 of the beams abut a supporting surface. The method also includes providing a plurality of fibre cement plates 104, for example, a first fibre cement plate 104a (shown in FIGS. 10 to 13), a second fibre cement plate 104b (shown in FIGS. 11 to 13), a third fibre cement plate 104c (shown in FIGS. 12 and 13), and a fourth fibre cement plate 104d (shown in FIG. 13). The method includes a step at which the first plate 104a is attached to at least one of the beams 102 via fasteners, for example screws. In an embodiment, as shown in FIG. 10, the first plate 104a is attached such that the first plate is arranged at a lower left corner of the array of beams 102 and completely covers a width of the left most beam 102. Also, the first plate 104a is arranged or attached to the at least one beam 102 such that the first longitudinal edge 120 is oriented horizontally and defines the bottom edge of the first plate 104a, while the second longitudinal edge 122 defines the top edge of the first plate 104a and is also oriented horizontally. Accordingly, the elongated groove 132 is arranged proximate to the lower ends 106 of the beams 102 and is disposed facing the supporting surface and the elongated projection 130 extends vertically upwardly.

Similarly, the first lateral edge 124 is oriented vertically and is arranged substantially parallel to the beams 102 and defines a left side edge of the first plate 104a, while the second lateral edge 126 defines a right side edge of the first plate 104a which is also oriented in a vertical direction. It may be noted that lengths of the longitudinal edges 120, 122 are larger/greater than lengths of the lateral edges 124, 126 in this embodiment.

After attaching the first plate 104a, the second plate 104b is engaged with the first plate 104a and is attached to one or more beams 102 using fasteners. For engaging the second plate 104b with the first plate 104a, as shown in FIG. 11 , the first lateral edge 124 of the second plate 104b is arranged facing the second lateral edge 126 of the first plate 104a and is aligned with the second lateral edge 126 of the first plate 104a. Thereafter, the second plate 104b is slid towards the first plate 104a such that the elongated projection 142 of the second lateral edge of the first plate 104a is inserted inside the elongated groove 140 of the first lateral edge of the second plate 104b. As the elongated projection 142 of the first plate 104a is inserted inside the elongated groove 140 of the second plate 104b, the sealant 160 present inside the elongated groove 140 of the second plate 104b is squeezed out (as shown in FIG. 9), causing the sealant 160 to move outwardly. In so doing, the sealant 160 flows outwardly between the elongated groove 140 of the second plate 104b and the elongated projection 142 of the first plate 104a, thereby the sealant 160 is arranged between the elongated groove 140 of the second plate 104b and the elongated projection 142 of the first plate 104a. Accordingly, the vertical joint between the first plate 104a and the second plate 104b is sealed by the sealant 160. In this manner various plates 104 are arranged horizontally in a first row 110.

It should be noted that in the figures, the elongated projection of the lateral edges is on the right side of the plate and the elongated groove of the lateral edges is arranged on the left side of the plate. However, within the scope of the invention, the opposite arrangement could also be made. Likewise, the construction is started at the lower left corner in the figures and plates are added from the right. However, the situation where the plates are started at the lower right corner and plates are added from the left could also be made.

Furthermore, it should be noted that in the figures, it is shown that the plates are rectangular plates with the horizontal edges being longer than the vertical edges. However, within the scope of the invention, the plates could also be arranged such that the vertical edges are longer than the horizontal edges. Likewise, square plates could also be imagined.

Subsequently, the third plate 104c is arranged in a second row 110 and is coupled with the first plate 104a. For so doing, as shown in FIG. 12) a bottom edge 120 of the third plate 104c is aligned with the top edge 122 of the first plate 104a and the third plate 104c is moved vertically downwardly. In so doing, the elongated projection 130 of the first plate 104a is inserted inside an elongated groove 132 of the third plate 104c, thereby connecting the third plate 104c with the first plate 104a. As shown, the third plate 104c is engaged with the first plate 104a such that a second lateral edge 126 of the third plate 104c is arranged at an offset from the second lateral edge 126 of the first plate 104a. In this way, the lateral edges of an upper row are not aligned with the lateral edges of a lower row. This increases the strength of the wall structure.

Thereafter, as shown in FIG. 13, the fourth plate 104d is attached to the third plate 104c in a manner similar to the attachment of the second plate 104b with the first plate 104a. Also, the fourth plate 104d is engaged with the first plate 104a and the second plate 104b in a manner similar to the engagement of the third plate 104c with the first plate 104a. However, the process can be made easier on the builder, in that the fourth plate can be first placed on top of the first/second plate such that the lower edge of the fourth plate engages the upper edge of the first/second plate. The fourth plate can then be slid to the left to engage the elongated groove of the lateral edge of the fourth plate with the elongated projection of the lateral edge of the third plate. In this way, the builder can easily put the plate in place without having to hold the plate in a precise position. The builder can just roughly set the plate in place, then slide it horizontally into engagement with the third plate and then fasten the fourth plate to the support beams.

The second plate 104b, the third plate 104c, and the fourth plate 104d are also attached with the beams 102 using fasteners. In this manner, various plates 104 are engaged with the beams 102 and adjacent plates 104 to form the wall structure 100. As the plates 104 are engaged with each other by engaging the elongated projections 130, 142 with respective grooves 132, 140, a need for horizontal beams is eliminated to secure the plates 104 within the wall structure 100. Also, the elongated projections 130, 142 and grooves 132, 140 configuration of the plates 104 facilitates fastening of the plates 104 with the beams 102 at any location rather than aligning the edges 120, 122, 124, 126 with the beams 102 and connecting the edges 120, 122, 124, 126 with the beams 102. Also, a horizontally oriented staggered arrangement of plates 104 facilitates in reducing the chances of ingress of water or wind inside the wall structure 100 through the vertically oriented joints. Also, when compared to the prior art type wall structures, around 1/3 of the number of fasteners are used in attaching the fibre cement plates 104 with the beams 102. This is mainly due to the fact that the edges 120, 122 of the fibre cement plates 104 do not have to be supported by rear beams and fasteners along the edges.

It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description.