GB2592951A

GB2592951A - Improvements relating to insulated raft foundations

Info

Publication number: GB2592951A
Application number: GB2003549.9A
Authority: GB
Inventors: Graham Harris Hackett Simon
Original assignee: Balanced Earth Homes Ltd
Current assignee: Balanced Earth Homes Ltd
Priority date: 2020-03-11
Filing date: 2020-03-11
Publication date: 2021-09-15
Also published as: GB202003549D0

Abstract

A floor slab 200 comprising a base 210 and at least one upstanding side wall 220, wherein at least one bracing element 230 is arranged between the base and the upstanding side wall to resist movement of the upstanding side wall relative to the base. An insulated raft foundation formed of these slabs and a method for forming a raft foundation and assembling an insulated concrete formwork structure are also claimed. The bracing element may be internal to the slab mold and may be triangular or a right-angled rib. The mould may also incorporate tethers as lifting means and a wall locator.

Description

Improvements Relating to Insulated Raft Foundations

Field

The present invention relates to a floor slab for forming an insulated raft foundation of an insulated concrete formwork structure. The present invention also relates to such an insulated raft foundation, a method of forming such an insulated raft foundation and a method of assembling an insulated concrete formwork structure. In particular, the present invention relates to floor slabs which are left in-situ in and provide a connection interface to wall sections for the construction of insulated concrete formwork structures.

Background

Insulated concrete formwork (ICF) construction is a method of constructing a building involving the use of hollow lightweight block components, preferably formed of an insulation material, which fit together to create a cavity into which a settable material such as concrete can be poured. Once the settable material has cured, a high strength, continuous and insulated frame structure is provided which may have superior insulation properties (and therefore superior energy efficiency) compared to similar buildings constructed using traditional brick or timber-based methods. The placement of a liquid flow-able setting material also tends to provide a superior level of airtightness which contributes to the energy efficiency of said ICF structure.

Known ICF methods involve using standard sheets of insulation, cutting and forming these sheets on site to form a desired shape forming an up-stand of insulation to contain concrete when placed. These are generally not robust enough to support the placement of concrete without the need for additional shuttering or support provided by timber or metal formwork to buttress the insulation, which adds time and expense. The foundation is then built off with said hollow lightweight block components to form a hollow wall structure for pouring a settable material into. The walling units may be referred to as ICF blocks and the pre-assembled floor units may be referred to as an insulated raft foundation.

There are some difficulties associated with ICF structures which have reduced the uptake of this construction method. The assembly process is slow, since the insulated concrete formwork must be assembled to form a cavity into which concrete may be poured, and this cavity must be well-sealed to avert leakage of liquid concrete mixture. As such, the ICF structures must be assembled meticulously.

Buttressing of the ICF structures may also be required, and this is typically provided by proprietary propping and alignment systems which sometimes double-up as a working platform, many of which are not compliant with current health and safety law in the UK.

There are also many difficulties in the provision of apertures in the building, primarily for windows and doors, since any openings must be provided before the concrete is added, and the exact shape of the openings must therefore be determined in advance. Furthermore, such openings are weak points in the ICF structure, which can further result in concrete defects or blowouts.

The entire process can be more expensive than traditional building techniques in initial set-up, not least because the aesthetic appearance of the exposed insulation material is not that which is likely to be desired, and as such, further external layers, such as render or similar, must also be applied following construction.

Therefore there is a need for improvements in ICF methods and components which will address some of the problems associated with ICF construction discussed herein, in order for ICF to be more widely adopted by the construction industry so that more building owners and users can benefit from the potential advantages provided by ICF construction.

It is therefore an aim of the present invention to provide improvements to components and methods used in ICF construction, in particular relating to floor slabs for the formation of insulated raft foundations for ICF structures.

Summary of the Invention

Ground floor "floor slabs" may be arranged together to form a floor slab assembly which represents the complete footprint of the ICF structure. Such a floor slab assembly may rest directly on the ground (after suitable preparation and leveling) and may form the foundation of the ICF structure, for example when concrete is poured onto the floor slab assembly. Such a foundation may be referred to as an insulated raft foundation.

Floor slabs for insulated raft foundations may be formed from a base of insulation material to provide a thermal break between the ground and the building. Such floor slabs have an upstanding side wall or "shutter" on their outer edges which define the outer edge of the foundation/building, when a plurality of such floor slabs are arranged to together to form a floor slab assembly. Together the base and the upstanding side walls of the floor slabs in the floor slab assembly define a hollow (or trough) for pouring concrete into to form the insulated raft foundation, after curing of the concrete. When the concrete is poured into the hollow of the floor slab assembly a hydrostatic load is exerted on the upstanding side walls by the concrete.

The inventors have found that this load can deform the upstanding side walls which can in tum create problems for any formed walls subsequently built off the upstanding side wall. Either the wall components used to engage with the upstanding side walls and form the walls of the ICF structure will not fit as intended, or the walls produced would be non-straight or bowed in the finished ICF structure, which would require expensive and difficult replacement or remedial It is therefore one aim of the present invention, amongst others, to provide a floor slab or method that addresses at least one disadvantage of the prior art, whether identified here or elsewhere, or to provide an alternative to existing techniques and methods. For instance, it may be an aim of the present invention to provide a floor slab which addresses the problem of bowing and the need for secondary support for the upstanding side walls (shuttering) under the hydrostatic load of a liquid settable mixture such as concrete. It may be a further aim of the present invention to provide an alternative or improved connection arrangement between a floor slab arid wall components used to fowl the walls of an ICF structure.

According to aspects of the present invention, there is provided a floor slab, a floor slab assembly, an insulated raft foundation and methods as set forth in the appended claims.

Other features of the invention will be apparent from the dependent claims, and from the description which follows.

According to a first aspect of the present invention, there is provided a floor slab comprising a base and at least one upstanding side wall suitably arranged along an edge of the base, wherein at least one bracing element is arranged between the base and the upstanding side wall to resist movement of the upstanding side wall relative to the base.

In such floor slabs, the base is suitably substantially flat and substantially rectangular, and is suitable for use as a part of a floor and/or foundation, or for use to support a flooring material, in a building. The floor slab is suitably configured for use in an ICF construction, as described herein. Suitably the upstanding side wall is configured for attachment to a wall section, as described herein, as part of an ICF construction. Preferably, the floor slab is suitable for forming an insulated raft foundation for an ICF structure.

The inventors have found that the provision of the bracing element between the base and the upstanding side wall of the floor slab, to resist relative movement of the upstanding side wall and base, may prevent the undesired bowing of the upstanding side wall and a wall section attached to the upstanding side wall described above. The floor slab of this first aspect may therefore provide a more reliable ICF construction which may also be more time, cost and labour efficient than known ICF methods by overcoming the need for additional support of the upstanding side walls during pouring and setting of a settable material to form an insulated raft foundation. This may also provide additional buttressing of wall sections built off the upstanding wall sections and therefore reduce the need for additional buttressing of the formwork structure during pouring and setting of a settable material in the wall sections, which may for example involve the use of scaffolding around the formwork structure.

It will be appreciated that buildings are commonly designed to have straight walls meeting at right angles. However, some ICF buildings may have curved walls. In such buildings with curved walls, the above considerations still apply wherein the upstanding side wall and/or a wall section to which the upstanding side wall is attached, may deform from the curve intended by the design. Therefore the present invention applies equally to floor slabs intended to be used in buildings with curved or other alternative-shaped walls.

In the floor slab of this first aspect, the base may have a substantially quadrilateral shape, suitably a rectangle. The base is suitably substantially flat. The base suitably provides a section of foundation and flooring for a building. The floor slab may be placed together and suitably coupled with other floor slabs which provide other sections of foundation and flooring for said building, to provide a complete foundation and ground floor of said building. Therefore the floor slab may suitably comprise a rigid substrate for supporting a top flooring layer and suitably a damp proof layer for preventing moisture from passing through the floor slab from the ground onto which it is placed. Preferably, the floor slab is suitable for forming an insulated raft foundation for an ICF structure and therefore the base is suitably provided by an insulative material, for example an expanded polymeric material such as expanded polystyrene (EPS). The base suitably comprises a damp-proof layer on its underside. Suitably the floor slab is configured to be arranged in contact with other floor slabs to form a floor slab assembly as described above with the upstanding side walls forming a boundary of a hollow for receiving a settable building material, to form an insulated raft foundation. Suitably the hollow has a depth defined by the height of the upstanding side walls, which is at least as high as the intended thickness of the settable material (i.e. concrete). The base of the floor slab suitably comprises an engagement portion for engaging with a complementary engagement portion on an adjacent floor slab in a floor slab assembly. The engagement portion may comprise a cut-away portion in the base, for example a lip.

The at least one upstanding side wall of the floor slab may provide a bottom part of a wall (closest to a floor) of said building. Therefore the at least one upstanding side wall of the floor slab is suitably arranged substantially perpendicular to the base. This suitably facilitates the construction of a wall which conforms to the intended shape (whether that be straight, curved or any other shape) and is perpendicular to said floor in said building, in conjunction with appropriate wall sections. Suitably the at least one upstanding side wall of the floor slab is arranged perpendicular to the base, the base suitably being flat and level.

In such floor slabs, the edge of the base suitably defines the outer edge of the footprint of the ICF structure to be built. Therefore the at least one upstanding side wall is suitably arranged along an edge of the base. The edge of the base and the upstanding side wall can then provide part of an outer layer of continuous insulation forming the wall of the ICF structure.

The floor slab may comprise more than one upstanding side wall, depending on which part of the floor/foundation of said building the floor slab is intended to provide. For example, if the floor slab is to provide a section of floor having one wall running across it, then the floor slab will comprise one upstanding side wall. If the floor slab is to provide a section of floor of said building having two walls running across it, then the floor slab will comprise two upstanding side wall sections. Such a floor slab comprising two upstanding side walls may provide a section of floor/foundation at a corner of said building, for example by comprising two upstanding side wall sections arranged along adjacent edges of the base of the floor slab, suitably joining to make a right-angled corner, in a building wherein the walls are straight and meet at right angles.

Suitably the at least one upstanding side wall is arranged at an outer edge of the base. Suitably the at least one upstanding side wall provides a bottom part of a wall which will become an exterior wall of an ICF building.

In some embodiments, the at least one upstanding side wall is a separate part to the base and is therefore attached to the base by a suitable fixing. In alternative embodiments, the at least one upstanding side wall is formed integrally with the base and therefore the base and the at least one upstanding side wall are formed from the same (continuous) material.

Suitably the at least one upstanding side wall section comprises a wall locator arranged at an upper edge of the upstanding side wall for engagement with a wall section. By providing wall locators, assembly of the ICF building and in particular alignment of the wall sections can be facilitated, reducing the propensity for tilting of the walls once installed. The wall locators may also advantageously act as a plug for the wall cavity, limiting leak pathways for the settable material when poured into the wall cavity. The wall locator may be an elongate tongue extending from the upper edge of the upstanding side wall for engagement with a complementary groove on said wall section. The elongate tongue may extend across substantially the entire length of the upstanding side wall section. Altematively, the wall locator may be a groove for engagement with a complementary elongate tongue on said wall section. In a further alternative, both the wall locator and said wall section may comprise a groove and a separate elongate tongue member may be provided to engage with both the wall locator and said wall section to connect the two together. In a further alternative, both the wall locator and said wall section may comprise an elongate tongue and a separate elongate member comprising an upper groove and a lower groove may be provided to engage with both the wall locator and said wall section to connect the two together.

The bracing element The floor slab of this first aspect comprises at least one bracing element arranged between the base and the upstanding side wall to resist movement of the upstanding side wall relative to the base. The bracing element is suitably attached to the upstanding side wall and to the base. The bracing element is suitably attached to an inside face of the upstanding side wall and an upper face of the base. Suitably the bracing element is arranged at a join where the inside face of the upstanding side wall meets the upper face of the base.

In some embodiments the bracing element has an approximate shape of a triangular prism. Suitably the bracing element is shaped as a triangular prism.

In some embodiments, the bracing element has an approximate L-shape. Suitably the bracing element is an L-shaped reinforcing rib.

The bracing element may be elongate with respect to the upstanding side wall of the floor slab.

The bracing element may extend lengthwise along at least half of the length of the upstanding side wall, suitably along at least 75% of the length of the upstanding side wall, suitably substantially along the length of the upstanding side wall or along the entire length of the upstanding side wall.

In some embodiments, the bracing element may be an elongate triangular prism.

In some embodiments, the bracing element may be an elongate L-shaped reinforcing member.

The bracing element of the floor slab of this first aspect may be a plurality of bracing elements, each arranged between the base and the upstanding side wall, each suitably attached to an inside face of the upstanding side wall and an upper face of the base. For example, the floor slab of this first aspect may comprise a plurality of triangular prism-shaped bracing elements or a plurality of L-shaped bracing elements, each arranged between the base and the upstanding side wall.

Suitably the bracing element or elements extend upwards with respect to the upstanding side wall sufficiently to perform the function of resisting bowing and/or transverse movement of the upstanding side wall upon filling a hollow in a floor slab assembly comprising a plurality of floor slabs according to this first aspect (to form an insulated raft foundation) and suitably to also at least partially resist bowing and/or transverse movement of the upstanding side wall upon filling a wall cavity of a wall section arranged on the upstanding side wall with a settable material. Suitably the bracing element or elements extend from the join of the base and the upstanding side wall to at least half the height of the upstanding side wall. In some embodiments, the bracing element or elements extend from the join of the base and the upstanding side wall to the top of the upstanding side wall.

Suitably the bracing element or elements is/are sufficiently rigid to resist bowing and/or transverse movement of the upstanding side wall caused by a settable material as described above. Suitably the bracing element or elements are formed of a sufficiently rigid material, for example metal, wood or rigid plastic. In some embodiments, the bracing element is formed of the same material as the floor slab, for example a rigid insulation material such as EPS.

In embodiments wherein the bracing element or elements is/are attached to the upstanding side wall and to the base, suitably to an inside face of the upstanding side wall and an upper face of the base, the bracing element or elements may be attached by adhesive or by fixings, for example adhesive, nails or screws. Alternatively, the bracing elements may be formed as part of the flooring slab during the manufacturing process, for example in a blow moulded floor slab or floor slab component. Therefore the upstanding side wall, the base and the bracing element may all be formed integrally from a rigid insulation material, for example EPS.

In some embodiments, the bracing element or elements is/are arranged inside either or both of the base of the floor slab and the upstanding side wall. Therefore the bracing element or elements may be integrally formed with either or both of the base and the upstanding side wall, suitably integrally formed with both of the base and the upstanding side wall. Such embodiments may have the advantage that the bracing element or elements do not interrupt the regular surfaces and right-angle join of the base and the upstanding side wall and therefore do not complicate the subsequent application of further building materials to the base and/or walls of an ICF building comprising a floor slab according to this first aspect. In such embodiments, the bracing element is suitably an elongate L-shaped reinforcing member or a plurality of L-shaped reinforcing ribs arranged inside (and therefore integral to) the base and the upstanding side wall, at the join of the base and the upstanding side wall.

In some embodiments, the bracing element is provided by a sloped (of chamfered) inside face of the upstanding side wall. In such embodiments, the bracing element is an integral part of the upstanding side wall. In such embodiments the whole upstanding side wall may have a substantially triangular prism shape (or wedge shape) suitably having a thin end at the top of the upstanding side wall and a thick end where the upstanding side wall meets the base, relative to the vertical dimension of the upstanding side wall. Alternatively, the upstanding side wall may comprise a triangular prism-shaped section, suitably having an upper thin end and a lower thick end where the upstanding side wall meets the level of the base. In such embodiments, the upstanding side wall may have an upper rectangular strip extending from the triangular prism-shaped section.

Such an arrangement provides the upstanding side wall with increased rigidity and resistance to transverse movement or bowing than an upstanding side wall.

Further features of the floor slab The floor slab of this first aspect suitably comprises a damp-proof layer. Such a damp-proof layer suitably prevents moisture passing through the floor slab from the ground on which the ICF structure comprising the floor slab is erected to the inside of said ICF structure.

The floor slab of this first aspect suitably comprises, in the base, a plurality of tethers for attachment of lifting gear, wherein the tethers are positioned to allow the floor slab to be lifted vertically whilst maintaining a horizontal orientation, when lifting gear is attached to the tethers.

Typical floor slabs used in ICF construction are heavy building elements which require a powered vehicle for lifting and placing in the desired location. Providing a plurality of tethers in a specific arrangement to allow a balanced horizontal orientation of the floor slab to be maintained during lifting greatly facilitates the process of lifting and placing the floor slab and can therefore speed the process of constructing a foundation/ground floor (or an upper floor / ceiling or roof cassette) of an ICF building. The specific arrangement of the tethers on the floor slab for achieving this may be calculated, for example using suitable computer software, taking into account the size, weight and centre of gravity of the floor slab. For example, the base of the floor slab may comprise four tethers for the attachment of lifting gear, in a spaced apart arrangement around the centre of gravity of the floor slab, the positions of the tethers specifically calculated to maintain a balanced horizontal orientation during lifting. The tethers may be provided by eye screws or bolts fastened to the base, in the specific positions discussed above.

The above tether features may be applied to an upper floor / ceiling or roof cassette for use in an ICF structure. Therefore the present invention may provide a floor cassette or roof cassette comprising such tethers.

In some embodiments, a floor cassette (for an upper floor) may be provided which comprises a hand rail extending from an upper face of the base. Such a hand rail may improve the safety of a user working on top of the floor cassette. This may be particularly advantageous wherein the floor cassette is intended to form part of an upper storey floor of an ICF building in construction, on which a user may have to work to carry out the construction of the upper storeys of said ICF building. The hand rail may provide support to such a user and may prevent said user accidentally falling from an upper floor of said ICF building during construction. The hand rail may be formed from a suitable metal and can be fixed to the floor cassette by suitable fasteners, for example screws or bolts.

According to a second aspect of the present invention, there is provided an insulated raft foundation comprising a plurality of floor slabs according to the first aspect and a settable building material. Suitably the plurality of floor slabs are provided with complementary engagement portions as described above in relation to the first aspect, to allow adjacent floor slabs to connect to each other to form a floor slab assembly for receiving a liquid form of the sellable building material, for example unset concrete. Suitably the upstanding side walls of the floor slabs form a hollow for receiving and containing a liquid form of the settable building material. Suitably the sellable building material in the insulated raft foundation is set / cured, for example a set concrete. Suitably the settable building material in the insulated raft foundation is arranged on top of the bases of the floor slabs and extends between the upstanding side walls of the floor slabs. Suitably the settable building material forms a monolithic foundation/floor across the plurality of floor slabs.

The floor slabs used in this second aspect may have any of the suitable features and advantages described in relation to the floor slabs of the first aspect.

According to a third aspect of the present invention, there is provided a method of forming an insulated raft foundation, the method comprising the steps of a) providing a plurality of floor slabs according to the first aspect comprising at least one bracing element arranged between a base and an upstanding side wall of the floor slab to resist movement of the upstanding side wall relative to the base, to form a floor slab assembly comprising a hollow; b) applying an unset settable structural material to the hollow and allowing the unset settable structural material to harden, the bracing elements maintaining the shape of the upstanding side wall and base whilst the settable structural material hardens.

The floor slabs used in this third aspect may have any of the suitable features and advantages described in relation to the floor slabs of the first aspect.

The bracing elements of the floor slabs can advantageously provide buttressing of the upstanding side walls to resist outward bowing of the upstanding side walls during or after applying the unset settable structural material to the hollow. Suitably the method of this third aspect does not involve providing external support for the upstanding side walls before or during step b). For example, the method suitably does not involve the use of scaffolding for the above purpose.

According to a fourth aspect of the present invention, there is provided a method of assembling an insulated concrete formwork structure, the method comprising the steps of: a) providing a plurality of floor slabs according to the first aspect comprising at least one bracing element arranged between a base and an upstanding side wall of the floor slab to resist movement of the upstanding side wall relative to the base, to form a floor slab assembly comprising a hollow; b) applying an unset settable structural material to the hollow and allowing the unset settable structural material to harden, the bracing elements maintaining the shape of the upstanding side wall and base whilst the settable structural material hardens.

c) arranging at least one wall section on the floor slab by engaging the wall section with the upstanding side wall of the floor slab, the wall section having first and second wall layers held in a spaced-apart relationship by a plurality of rail members to define a wall-section cavity therebetween; d) applying an unset settable structural material to the wall-section cavity and allowing the unset settable structural material to harden, the bracing elements maintaining the relative arrangement of the upstanding side wall, base and wall section whilst the settable structural material hardens.

Suitably the steps of the method are carried out in the order step a) followed by step b) followed by step c) followed by step d). In some embodiments, the steps of the method are carried out in the order step a) followed by step c) and then steps b) and d) of applying the settable building material to the floor slab assembly and the wall section cavity respectively are carried out subsequently, in either order or suitably at the same time.

The suitable features and advantages of the floor slab used in the method of this fourth aspect are as described above in relation to the first aspect.

Suitably step a) involves providing a plurality of floor slabs, some or all of which are floor slabs according to the first aspect, arranged to form a complete floor/foundation of said insulated concrete formwork structure. The floor slabs of the first aspect suitably provide the floor/foundation parts which will comprise an outer wall in the insulated concrete formwork structure and the other floor slabs, if present, provide the floor/foundation parts which will have no outer wall in the insulated concrete formwork structure (and therefore do not comprise an upstanding side wall for connection to a wall section). Suitably the plurality of floor slabs are fixed together to form said complete floor/foundation.

Suitably step c) involves arranging a plurality of wall sections on a plurality of floor slabs according to the first aspect to form complete walls of a ground floor of said insulated concrete formwork structure, the walls comprising a continuous cavity suitable for pouring a settable material into in order to form said insulated concrete formwork structure. Suitably the floor slabs of the first aspect comprise wall locators arranged at upper edges of the upstanding side walls of the floor slabs for engagement with a complimentary wall locator of the wall sections.

Step d) involves applying an unset settable structural material to the wall-section cavity and allowing the unset settable structural material to harden. The unset settable structural material is suitably a concrete mix for forming a concrete in the cavity, after setting.

In the method of this fourth aspect, the bracing elements advantageously maintain the relative arrangement of the upstanding side wall, base and wall section whilst the settable structural material hardens, by resisting the outward pressure on the wall sections and the upstanding side walls exerted by the settable structural material in the cavity of the wall sections. Therefore the use of such bracing elements in the method of this fourth aspect may at least partially avoid the need for external structural support of the insulated concrete formwork structure during pouring and setting of the settable structural material, for example scaffolding.

Suitably steps a) and c) of the method of this fourth aspect provide a floor and walls of a ground floor of an insulated concrete formwork structure. The method of this fourth aspect can be used to form insulated concrete formwork structures having more than one floor (or storey) by repeating steps c) and d).

Step c) may involve arranging a plurality of floor (or roof) cassettes intended to provide an upper floor (or roof) of said ICF structure between the wall sections (of the ground floor). Suitably the walls sections are provided with hangers for engaging with the floor cassettes of the upper floor.

The floor (or roof) cassettes which form the floor of an upper storey of said insulated concrete formwork structure may suitably provide additional support of said structure by resisting relative movement of the walls before, during and after step d). Suitably the roof storey of the insulated concrete formwork structure is suitably provided, after step c) and any repeat of steps c) and d) where necessary, by a roof cassette which may not have to comprise the upstanding side walls of the floor slab of the first aspect, as the roof storey of the insulated concrete formwork structure may not comprise walls, only a roof structure. This of course depends on the specific design of the insulated concrete formwork structure. Therefore the uppermost cassettes used in the method may not be floor slabs according to the first aspect.

The floor cassettes of an upper storey (i.e. not the ground level) or the roof cassettes can advantageously provide buttressing of the wall sections of the storey beneath said floor or roof cassettes at or adjacent to an upper edge of the wall sections, to resist inward collapse or outward bowing of the wall sections during or after applying the unset settable structural material. Suitably the upper storey floor cassettes and or roof cassettes are used in this way as an alternative to using an external support for the walls of the insulated concrete formwork structure such as scaffolding. Suitably the method of this fourth aspect does not involve providing external support for the insulated concrete formwork structure before or during step c). For example, the method suitably does not involve the use of scaffolding for the above purpose.

The method of this fourth aspect may involve, prior to step c) providing an internal framework to the inside space of the insulated concrete formwork structure. Suitably the internal framework is a timber framework comprising a plurality of vertical and horizontal timber members. Such an internal framework allows for the assembly of the internal structure of the building, after step d), and also may advantageously provide further buttressing of the wall sections before and during step d). Such an arrangement may further obviate the need for external support for the walls of the insulated concrete formwork structure such as scaffolding.

Brief Description Of The Drawings

For a better understanding of the invention, and to show how example embodiments may be carried into effect, reference will now be made to the accompanying drawings in which: Figure 1 is a perspective view of a floor slab according to the first aspect of the present invention comprising bracing elements.

Figure 2 is a perspective view of a floor slab according to the first aspect of the present invention comprising alternative bracing elements.

Figure 3 is a perspective transparent view of a section of a floor slab comprising a bracing element according to the first aspect of the present invention.

Figure 4 is a perspective transparent view of a section of a floor slab comprising an alternative bracing element according to the first aspect of the present invention.

Figure 5 is a perspective view of a floor slab assembly for forming an insulated raft foundation according to the second aspect of the present invention.

Figure 6 is a perspective view of an insulated raft foundation according to the second aspect of the present invention.

Figure 7 is a perspective view of an insulated concrete formwork structure comprising floor slabs according to the first aspect of the present invention.

Detailed Description Of The Example Embodiments

Figure 1 shows a floor slab 100 for forming an insulated raft foundation for an insulated concrete framework structure. The floor slab 100 has a rectangular footprint and comprises base 110, upstanding side walls 120, bracing elements 130 and tethers 140. Base 110 is formed of a piece of high density expanded polystyrene (EPS) and is shaped to comprise a step having bottom base layer 111 extending out from top base layer 112 to form lip region 113 along two sides of the rectangular floor slab 100. The base 110 may be formed from a single piece of EPS or may be formed from two pieces of EPS bonded together, one providing the top base layer 112 and one providing the bottom base layer 111. The base layer may have a thickness of approximately 200 mm. The lip region 113 is intended to engage with a complementary shaped base layer of an adjacent floor slab in order to arrange the floor slabs together to form a floor slab assembly and subsequently an insulated raft foundation.

The upstanding side walls 120 are arranged on and fixed to the upper surface of the bottom base layer 111, along two adjoining side edges of the floor slab 100. The upstanding side walls 120 therefore are intended to form the base of two walls of an insulated concrete framework structure which form a corner of said structure. Alternatively, such a floor slab 100 could be provided with only one upstanding side wall 120 along one edge of the base 110 in order to provide an area of floor of an insulated concrete formwork structure which only has a wall along one edge. Other configurations of upstanding side walls 120 could be used according to the design of said insulated concrete formwork structure. For example, the upstanding side walls may have gaps in order to make space for a doorway or window.

The upstanding side walls 120 comprise inner faces 121, outer faces 122 (not shown), upper edges 123 and side edges 124. The outer faces 122 are flush with the side edges of the base 110. The upper edges 123 comprise a wall locator in the form of tongues 125 which are configured to engage with a complementary groove in a wall section to allow assembly of an insulated concrete formwork structure. The side edges 124 comprise either a groove 126 or a tongue 127 configured to engage with a complementary groove or tongue respectively of upstanding side walls of adjacent floor slabs, in order to connect the floor slabs together to form a floor slab assembly of an insulated raft foundation.

The upstanding side walls 120 may be formed of a suitable sheet material, for example EPS, and attached to the base layer 110 with suitable fixings or adhesive. The sheet material may be machined to provide the required parts such as tongues 125. Alternatively the upstanding side walls 120 may be formed by blow moulding into the required shape comprising tongues 125.

The bracing elements 130 are elongate triangular prisms in shape, having a sloped inner face 131, an outer face 132, a bottom face 133 and ends 134. The bracing elements 130 are arranged on and fixed to the upstanding sides walls 120 and the top base layer 112 of base 110. The bracing elements 130 extend along the majority of the length of the upstanding side walls 120. The outer face 132 of the bracing elements 130 contact the inner faces 121 of the upstanding side walls 120 and the bottom face 133 of the bracing elements 130 contact the upper surface of the top base layer 112 of base 110. The sloped inner faces 131 of the bracing elements 130 face away from the upstanding side walls 120. The two bracing elements 130 comprise mitred ends which meet at corner joint 128. The shape, mass and position of the bracing elements 130 provide a reinforcement of the upstanding side walls 120 to resist deformation of the upstanding side walls 120 during pouring and setting of concrete into a hollow of a floor slab assembly comprising floor slab 100. This removes to the need for the upstanding side walls 120 to be braced externally, for example by scaffolding.

The upper layer 112 of the base 110 is provided with four tethers 140 which comprise eyes for attaching lifting gear to the tethers 140 in order to lift the floor slab into position, for example using a crane. The tethers 140 are fixed into the base layer a large surface area nut which is sandwiched between the upper base layer 112 and the lower base layer 111. In some embodiments a different number of tethers 140 could be used, for example three tethers Figure 2 shows a floor slab 200 for an insulated framework structure, which is similar to floor slab 100 and comprises base 210, upstanding side walls 220 and bracing elements 230. As an alternative to the elongate bracing elements 130 of floor slab 100, floor slab 200 comprises a plurality of relatively short bracing elements 230. The bracing elements 230 are triangular prism shaped and are generally as described in relation to the bracing elements 130 of floor slab 100 in terms of shape, fitting and function. The plurality of bracing elements 230 may provide a similar effectiveness in reinforcing the upstanding side walls 220, but using less total material than the elongate bracing elements 130, which may save on material costs in the construction of the floor slab 200 compared to the floor slab 100.

Figure 3 shows a part (cut-away) of a floor slab 300 where the base 310 and the upstanding side wall 320 are integrally formed, for example by blow moulding an EPS material. The floor slab 300 comprises a plurality of bracing elements 330 within the floor slab. The bracing elements 330 are L-shaped and are formed of a rigid material such as steel. The bracing elements are arranged so that they extend within the upstanding side wall 320 and the base layer 310 of the floor slab 300 and function by reinforcing the upstanding side wall to resist deformation and movement relative to the base layer 310 during concrete pouring as described above.

Figure 4 shows a part (cut-away) of a floor slab 400 similar to floor slab 300 wherein the bracing element 330 of floor slab 300 has been replaced with an elongate L-shaped bracing element 430 which is otherwise similar in construction, positioning and function to bracing element 330 in floor slab 300.

Figure 5 shows a floor slab assembly 500 comprising four floor slabs 100 as described in relation to Figure 1, the floor slabs 100 comprising upstanding side walls 120 and bracing elements 130. The floor slabs 100 together form trough 510 in the floor slab assembly, for receiving a settable building material such as concrete.

Figure 6 shows an insulated raft foundation 600 comprising concrete slab 610 formed by pouring and setting a concrete mixture in trough 510 of floor slab assembly 500 of Figure 5. During pouring and setting of the concrete mixture in trough 510, the bracing elements 130 of floor slabs 100 resist deformation of the upstanding side walls 120 to maintain the desired, in this case straight and square, shape of the upstanding side walls 120, without the need for external buttressing. This allows an ICF structure to be readily constructed off the undeformed upstanding side walls.

Figure 7 shows an insulated concrete formwork structure 700 (before the addition of an unset sellable structural material into the wall cavities). The ICF structure 700 comprises insulated raft foundation 600 formed of floor slabs 100, which are according to the first aspect of the present invention and may be as described in relation to floor slabs 100 and 200 of Figures 1 and 2 respectively, with the necessary changes being made to the number and arrangement of upstanding side walls in said floor slabs to conform to the particular design of insulated concrete formwork structure 700. The floor slabs 100 therefore comprise bracing elements as described above (not shown) which support the upstanding side walls 120. The raft foundation also comprises concrete slab 610 formed from unset concrete poured into a hollow 510 (or trough) formed by the floor slabs 100, bounded by the upstanding side walls 120 of the floor slabs 100. The bracing elements in the upstanding side walls of the floor slabs 100 have resisted deformation of the upstanding side walls during pouring and setting of the concrete and are therefore straight and square. The structure 700 comprises wall sections 720 arranged on the upstanding side walls 120 of floor slabs 100 using a wall locator in the form of a tongue on the upstanding side walls and a groove in the bottom edge of the wall sections 720, as described above. The wall sections 720 comprise inner wall layer 722, outer wall layer 723 and a cavity 721 therebetween suitably for pouring into an unset settable structural material such as concrete. The wall sections 720 comprise hangers (not shown) for attaching and supporting upper floor cassettes 740. The structure 700 is also provided with internal timber framework 730 which defines and will become the internal walls of the structure 700, once construction is complete. The internal framework 730 provides additional support for upper floor cassettes 740. The upper floor cassettes 740 provide a floor base for a first storey of structure 700. The upper floor cassettes may be provided with handrails to improve the safety of users working on top of the upper floor, for example when the unset settable structural material is being poured into the cavity 721. The combination of the bracing elements in the floor slabs 100, the internal timber framework 730 and the upper floor cassettes 740 suitably provide stability to structure 700 so that deformation of the wall sections 720 is resisted and prevented before, during and after an unset settable structural material is poured into the hollow formed by the floor slabs 100 and into the cavity 721. Therefore structure 700 may be constructed without the need for external bracing of the upstanding side walls of the floor slabs 100 and the wall sections 720, which may speed up and reduce the cost of the construction process, compared to known insulated concrete formwork structures.

In summary, the present invention provides floor slabs for forming insulated raft foundations. Such floor slabs are suitable for insulated concrete formwork (ICF) constructions. The floor slab comprises a base and at least one upstanding side wall attached to or formed integrally with the base. The at least one bracing element is arranged between the base and the upstanding side wall to resist movement of the upstanding side wall relative to the base and therefore support the upstanding side wall during construction. The bracing element suitably prevents the upstanding side wall from bowing during pouring and setting of an unset settable building material (for example a concrete composition) to form an insulated raft foundation, which exerts a significant outward force on the upstanding side wall. The bracing element may therefore prevent defects in the upstanding side walls (and subsequent ICF structure) and/or avoid the need for additional external support or buttressing for the upstanding side walls during construction. An insulated raft foundation formed with such floor slabs and methods of forming an insulated raft foundation and an insulated concrete formwork structure are also provided.

Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

Throughout this specification, the term "comprising" or "comprises" means including the component(s) specified but not to the exclusion of the presence of other components. The term "consisting essentially of' or "consists essentially of" means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effect of the invention.

The term "consisting of' or "consists of' means including the components specified but excluding addition of other components Whenever appropriate, depending upon the context, the use of the term "comprises" or "comprising" may also be taken to encompass or include the meaning "consists essentially of" or "consisting essentially of', and may also be taken to include the meaning "consists of" or "consisting of".

The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or exemplary embodiment of the invention as set out herein are also to be read as applicable to any other aspect or exemplary embodiments of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each exemplary embodiment of the invention as interchangeable and combinable between different exemplary embodiments.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

Claims 1. A floor slab comprising a base and at least one upstanding side wall, wherein at least one bracing element is arranged between the base and the upstanding side wall to resist movement of the upstanding side wall relative to the base.
2. The floor slab according to claim 1, wherein the base is substantially rectangular.
3. The floor slab according to claim 1 or claim 2, wherein the at least one upstanding side wall is arranged substantially perpendicular to the base.
4. The floor slab according to any preceding claim, wherein the bracing element is attached to an inside face of the upstanding side wall and an upper face of the base.
5. The floor slab according to any of claims 1 to 3, wherein the bracing element is integrally formed with the base and/or the upstanding side wall
6. The floor slab according to any preceding claim, wherein the bracing element is a triangular prism.
7. The floor slab according to claim 6, wherein the bracing element is an elongate triangular prism.
8. The floor slab according to any of claims 1 to 4, wherein the bracing element is an L-shaped reinforcing rib.
9. The floor slab according to any preceding claim, wherein the upstanding side wall comprises a wall locator arranged at an upper edge of the upstanding side wall for engagement with a wall section.
10. The floor cassette according to claim 9, wherein the wall locator is an elongate tongue extending from the upper edge of the upstanding side wall for engagement with a complementary groove on said wall section.
11. The floor slab according to any preceding claim, wherein the base comprises a damp-proof layer.
12. The floor slab according to any preceding claim, wherein the base comprises a plurality of tethers for attachment of lifting gear, wherein the tethers are positioned to allow the floor slab to be lifted vertically whilst maintaining a horizontal orientation, when lifting gear is attached to the tethers.
13. An insulated raft foundation comprising a plurality of floor slabs according to any preceding claims and a settable building material.
14. A method of forming an insulated raft foundation, the method comprising the steps of: a) providing a plurality of floor slabs according to any of claims 1 to 12, comprising at least one bracing element arranged between a base and an upstanding side wall of the floor slab to resist movement of the upstanding side wall relative to the base, to form a floor slab assembly comprising a hollow; b) applying an unset settable structural material to the hollow and allowing the unset settable structural material to harden, the bracing elements maintaining the shape of the upstanding side wall and base whilst the settable structural material hardens.
15. A method of assembling an insulated concrete formwork structure, the method comprising the steps of: a) providing a plurality of floor slabs according to the first aspect comprising at least one bracing element arranged between a base and an upstanding side wall of the floor slab to resist movement of the upstanding side wall relative to the base, to form a floor slab assembly comprising a hollow; b) applying an unset settable structural material to the hollow and allowing the unset settable structural material to harden, the bracing elements maintaining the shape of the upstanding side wall and base whilst the settable structural material hardens.c) arranging at least one wall section on the floor slab by engaging the wall section with the upstanding side wall of the floor slab, the wall section having first and second wall layers held in a spaced-apart relationship by a plurality of rail members to define a wall-section cavity therebetween; d) applying an unset settable structural material to the wall-section cavity and allowing the unset settable structural material to harden, the bracing elements maintaining the relative arrangement of the upstanding side wall, base and wall section whilst the settable structural material hardens.