The present invention relates to a building foundation. More especially, the invention relates to a modular structure that provides a load bearing insulated foundation for a building.

All buildings require a foundation to transfer load to the earth. There are generally two types of foundation. Shallow foundation is, usually, embedded a meter or so into soil. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock. Another common type is the slab-on- grade foundation where the weight of the building is transferred to the soil through a concrete slab placed at the surface. Deep foundation is used to transfer a load from a structure through an upper weak layer of soil to a stronger deeper layer of soil. There are different types of deep foundations including helical piles, impact driven piles, drilled shafts, caissons, piers, and earth stabilized columns. The naming conventions for different types of foundations vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, and pre-tensioned concrete.

The structure and form of foundations is quite complex. Generally, foundations are designed to have an adequate load capacity with limited settlement by a geotechnical engineer, and the foundation itself is designed structurally by a structural engineer.

The construction of foundations form a substantial part of the building construction process and are labour intensive. The present invention seeks to provide a load-bearing insulated modular frame structure, providing a foundation for a building which rests on the desired ground surface thus removing the need to dig to any great depth into the earth, with all the labour and time that this involves.

A modular frame structure for shuttering is disclosed in DE10062831. The application discloses base plates and edge elements that form a closed outer frame in which concrete is poured. The frame disclosed is not load bearing and cannot therefore be considered a structure providing a foundation for a building. Rather the frame provides a boundary to shape the concrete and provides an insulated barrier to the earth. Other constructions techniques associated with traditional foundations, for example, strip footings, are still required to support a building using such a frame.

According to one aspect of the invention, there is provided a load-bearing frame structure providing a foundation for a building, wherein the frame structure, in use, rests on the surface of the ground.

The frame structure may be modular in construction. This allows the frame to be designed to any chosen shape or size.

The frame structure may be made from expanded polystyrene or similar load-bearing material. This allows the frame to bear all the load of the building whilst also providing an insulated barrier to the earth. The frame is preferably shaped and designed to spread the load across the entire frame.

Preferably the frame consists of a number of modular sections including edge pieces and straight sections.

The edge pieces may be formed from foot and leg portions, the leg portion being angled at between 60° and 90° to the foot portion. Preferably the leg portion is angled at between 75° and 85° to the foot portion. Preferably still the leg portion is angled at approximately 80° to the foot portion. This angle ensures that the load is spread across the entire corner of the edge piece.

In a second aspect, there is provided a method of constructing a foundation for a building, the method comprising the steps of : selecting a number of frame elements from straight and edge pieces; locating the elements on the ground surface; interlocking adjacent elements to form a frame; and pouring reinforced concrete between the boundaries of the frame.

One embodiment of the invention will now be described by way of example with reference to the accompanying figures in which : Figure 1 is a plan view of a simple frame constructed in accordance with the present invention;

Figure 2 is a sectional view of a floor panel unit of the frame of Figure 1; and

Figure 3 is a sectional view of an edge piece of the frame of Figure 1.

The figures show a frame 2 suitable for providing a foundation for a building (not shown). Figure 1 shows a frame 2 in its most basic form, a square. The frame 2 is of modular design and is constructed from straight floor panel elements 4 (shown in figure 2) and edge piece elements 6 (shown in figure 3).

Each element 4, 6 (and hence the entire frame) is constructed from expanded polystyrene or similar material that is capable of bearing loads of the level required for building foundations. The material also provides an insulated barrier to the earth.

Each element 4, 6 has ends 8 which are capable of interlocking with an adjacent element such that a selection of elements 4, 6 link together to form a frame which can be formed of any shape or size (by choosing a suitable number of straight and edge elements).

Although the present description refers only to straight and edge elements, it is clearly envisaged that elements can be formed of any shape, such as, for example, curved elements. It is critical however that such elements must also be load bearing and designed in such a way as to spread the load across the entire element.

The dimensions of a floor panel element 4 are typically 1145 cm length, 60 cm width and 200 cm height. It should be appreciated that these dimensions are merely given as examples to provide the reader with an idea of the sizes involved and no limitation whatsoever is intended to the actual dimensions of the elements.

An edge piece element 6 is shown in figure 3. The edge piece 6 comprises a foot portion 10 and a leg portion 12 extending upwardly from the foot portion 10. The leg portion 12 extends upwardly at an angle (A) of approximately 80°. This angle is chosen to dissipate the load on the edge piece element 6 in such a way that the load extends across the entire corner region rather than extending linearly towards corner of the edge (as can be seen in the dotted line in figure 3), which otherwise would occur if the leg portion 12 extended at 90°.

The outer top angle (B) of the leg portion 12 is approximately 100°.

The general dimensions of the edge piece element 6, again without any implied limitation, are 450 cm height, and 600 cm length.

The edge piece element 6 may have one or more recesses or apertures 14 to decrease the weight of the element 6 and/or to reduce the amount of material required. The chosen thickness and density of the frame elements 4, 6 depend on a number of conditions, most notably the type and strength of the soil at the foundation location. A poor soil, for example, may require the elements at that location to have a higher density.

In use, the foundation is laid by simply selecting various straight and edge elements 4, 6 and interlocking the elements to provide a frame in accordance with the proposed architectural structure of the building to be constructed. Once the frame is constructed, reinforced concrete is then poured between its boundaries.

The resulting foundation removes any need for strip footings which are otherwise required in traditional shallow foundation constructions, although where extremely poor ground conditions require deep foundations, piling could be used in conjunction with this foundation system.

The foundation is suitable for the majority of, if not all building constructions, subject only to the upper load bearing limitation of the foundation as delineated by a structural engineer. The foundation also conforms to all necessary statutory building regulations and standards such as passive house standards and low carbon efficiency standards.

It will be appreciated that the foregoing is merely an example of an embodiment and just some examples of its use. The skilled reader will readily understand that modifications can be made thereto without departing from the true scope of the invention.