EP1840275A1

EP1840275A1 - Method and apparatus for providing a foundation for a building

Info

Publication number: EP1840275A1
Application number: EP07251198A
Authority: EP
Inventors: Victor Bates
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-22
Filing date: 2007-03-21
Publication date: 2007-10-03
Also published as: GB0605776D0; GB2436339A; GB0705690D0; GB2436339B

Abstract

An apparatus for providing a foundation for a building comprises a pre-formed shuttering set (4) which, in transverse, cross-section defines a vertical leg (10) for retaining concrete and a horizontal leg (11) that extends inwardly of the building from the top of the vertical leg (10) so that it is, in use, supported by the concrete retained by the vertical leg (10). The shuttering set (4) is positioned at a use location and levelled before pouring the concrete into the shuttering set (4), which concrete is at least partly retained by the vertical leg (10) and underlies and provides support for the horizontal leg (11). The concrete is then allowed to at least partially cure; before constructing a wall on the horizontal leg (11) aligned with a guide provided by the horizontal leg (11).

Description

This invention relates to a method and apparatus for providing a foundation for a building. The preferred embodiment provides a method and apparatus particularly suitable for providing a foundation for a conservatory or similar extension to a domestic dwelling. However, the invention is not limited to such applications and may be used under a wide range of circumstances to provide a foundation for many different types of building.
It is well understood that a fundamental pre-cursor to the construction of many buildings, including conservatory type extensions, is the provision of a foundation.
Traditionally, foundations have been provided by excavating a trench and back-filling the trench with concrete to provide a surface upon which a bricklayer can set out a brick or block wall which will form a support for the upper parts of the building. Depending on site conditions, the excavated trench may need partially back-filling with hardcore material and compacting, and shuttering may be required, prior to the pouring of the concrete. This traditional process has a number of disadvantages that are well recognised within the building trade. In particular, it is critically important to the overall success of the building project that the brick or block work is set out in precisely the correct position on the concrete foundation. The concrete foundation itself gives insufficient guide as to the correct position of the brick or block work and accordingly considerable care must be exercised by the bricklayer in setting out his work.
The problem is particularly acute if a factory pre-formed building, for example a conservatory, is to be erected on the base provided by the bricklayer. Small errors in the positioning or angles of the walls can lead to considerable difficulties in correctly fitting the pre-formed building. The necessary accuracy can only be obtained by skilled craftsmen spending a considerable amount of time and effort in the correct setting out of his work. This procedure is costly. The cost of the operation are further increased by the fact that the initial concrete strip must be allowed to at least partially cure before the bricklayer can start work. This will mean a delay of at least 24 hours between laying the concrete and starting the brick or block work. As a result, the construction of a suitable foundation for even a small conservatory will involve visits to the site on at least two separate days.
I have now devised a method, and an apparatus for use in that method, that obviates many of the disadvantages of traditional foundations as outlined above. The preferred embodiment of the invention allows considerable reduction in the time necessary to complete a foundation and removes the problem of inaccuracies in the setting out of the foundation walls, as outlined above.
According to a first aspect of the present invention a method for providing a foundation for a building comprises: pre-forming a shuttering set so that in transverse cross-section the shuttering set defines a vertical leg for retaining concrete and a horizontal leg that extends inwardly of the building from the top of the vertical leg so that it is, in use, supported by the concrete retained by the vertical leg; positioning the shuttering set at a use location; levelling the shuttering set; pouring the concrete into the shuttering set to be at least partly retained by the vertical leg and to underlie and provide support for the horizontal leg; allowing the concrete to at least partially cure; and constructing a wall on the horizontal leg aligned with a guide provided by the horizontal leg.
The guide can conveniently be the outer edge of the horizontal leg where it joins the vertical leg.
In effect, the exact line to which the bricklayer is to work in constructing the wall is defined in the preferred embodiment by the juncture between the horizontal leg and the vertical leg. Because the shuttering set is pre-formed it can be shaped to provide exactly the correct dimensions and angles for the required wall. All that is required on site is that the shuttering set be correctly positioned and levelled before the concrete is poured. The fact that the wall is constructed on a horizontal leg of the shuttering set means that work on building the wall can commence at a relatively early stage of the cure of the concrete.
In the preferred embodiment of the invention the shuttering set includes a second vertical leg that extends upwardly from the inner edge of the horizontal leg to retain concrete so that the finished surface of the concrete is above the level of the horizontal leg. If desired, a second horizontal leg may extend inwardly of the building from the top edge of the second vertical leg to provide a surface on which an inner leaf of a cavity wall may be constructed. Again, the invention obviates the need for detailed setting out by the bricklayer since the outer edge of the inner leaf of the wall may be aligned with the outer edge of the second horizontal leg. In the alternative, the first horizontal leg may be wide enough to accommodate both the inner and outer leaf of the required wall. In these circumstances the inner leaf may be constructed at a pre-determined spacing from the outer leaf or may be constructed utilising a second guide provided by the shuttering set. The second guide may be, for example, a ridge formed on the horizontal leg or may be the second vertical leg.
In accordance with a second aspect of the invention there is provided apparatus for carrying out the method of the invention, the apparatus comprising a pre-formed shuttering set that, in transverse cross-section, defines a vertical leg for retaining concrete and a horizontal leg that extends inwardly of the building from the top of the vertical leg.
The invention will be better understood from the following description of a preferred embodiment thereof, given by way of example only, reference being had to the accompanying drawings wherein:

Figure 1 shows schematically and in cross-section an embodiment of apparatus in accordance with the present invention positioned for receipt of concrete;
Figure 2 is an enlarged perspective view of a portion of the shuttering set of the embodiment of Figure 1;
Figure 3 illustrates a levelling device;
Figure 4 illustrates schematically in plan view a shuttering set prepared for the receipt of concrete; and
Figure 5 is a front view of the arrangement of Figure 4.

Referring firstly to Figure 1 there is illustrated in schematic cross-section a typical arrangement for a foundation utilising the method and apparatus of the present invention. The ground 1 at the site where the foundation is required has been excavated to provide a trench 2. Soil has been removed over the entire area of the proposed building to provide a platform 3 to be covered with concrete at the same time as the trench 2 is filled. The exact dimensions of the trench will be determined in light of the soil conditions and structural requirements for the building to be erected on the foundation.
In accordance with the present invention there is provided a shuttering set 4 that is supported on a plurality of screw jacks 5 each of which has a sole plate 6 resting on the floor 7 of the trench 2. The jacks 5 allows the shuttering set to be raised and lowered and each jacking location for levelling purposes. The datum level for the shuttering set may be established by any suitable means. In a typical use of the present invention for the construction of a foundation for an extension to a building the datum will generally be established by reference to the existing building by securing the shuttering set to the building at a pre-determined position. Under these circumstances, after the shuttering set has been secured to the building the jacks 5 will be positioned and operated to level the entire shuttering set.
The shuttering set is shown in more detail in Figure 2. It will be seen to comprise a first vertical leg 10, a horizontal leg 11 and a second vertical leg 12. In the illustrated embodiment of the invention the legs are extrusions of suitable material, for example aluminium, and the vertical legs 10 and 12 are formed from the same profile. The vertical legs 10, 12 are formed with profiles interlocked with opposite lateral edges of the horizontal leg 10. A stabilising bar 13 is secured to the horizontal leg by suitable means, (for example bolts having their heads retained in slots 29 provided for the purpose on the underside of the horizontal leg 11), and extends across the shuttering set to the opposite side thereof where it is joined to a corresponding horizontal leg (not shown). Stabilising bars are positioned as necessary to give the shuttering set adequate resistance to spreading. Preferably, one or more diagonal bracing bars 14 (Figure 4) are also secured to the horizontal legs of the shuttering set to ensure squareness.
If it is necessary for the concrete slab to be reinforced the required reinforcing steel 15 can conveniently be supported by resting it on the stabilising bars 13. By this means the steel can be positioned at an optimum location without the need for any additional support. In the illustrated embodiment of the invention further stabilising bars 16 are secured to a flange 17 of the upper leg 12 to provide additional stabilising to the structure. Further steel reinforcing mesh 18 may be supported on the upper stabilising bars 16 if desired.
The structure of the jacks 5 is shown in more detail in Figure 3. Each jack 5 consists of a tube 19 supported on and secured to the sole plate 6 and furnished, at the upper end thereof, with a threaded insert 20. A threaded rod 21 engages the threads of the insert 20 and carries at its upper end a plate 22. The plate 22 is supported on a nut 23 that engages the threaded rod 21. A second nut 24 is locked to the first nut 23 with a washer therebetween so that the rod 21 may be rotated relative to both the plate 22 and the insert 20 by applying a spanner to the nut 24. By this means, the shuttering may be raised or lowered at the location of each jack 5. It is envisaged that a jack 5 will be provided at each change of direction of the shuttering set. Accordingly, in the simple rectangular foundation illustrated in Figure 4 a jack 5 will be provided at each of the corners 25, 26. If necessary, depending on the length of the sides and the structural rigidity of the materials used for the shuttering, additional jacks may be required, for example at the mid-side location 27 illustrated in Figure 4. When the jacks are located at corners the plate 22 is preferably shaped to assist in forming the corner. For example, if the jack is located at a right-angle corner such as at 25 and 26 the plate 22 is conveniently in the form of an L shape having legs of equal length that extend along both of the adjacent horizontal legs 11 of the shuttering set. Preferably, as seen particularly in Figure 3, the plate 22 is located using grooves 28 provided by the material of the horizontal leg 11. Suitable fastenings may be used to lock the horizontal legs 11 to the plates 22.
The basic arrangement of one horizontal and two vertical legs illustrated in Figure 3 may suffice for certain applications. However, for many applications it will be desirable to add a further horizontal leg 30 to the upper end of the vertical leg 12 to extend inwardly of the building. Additionally, it may in many instances be desirable to add a flexible skirt 31 to the outer side of the lower vertical leg 10. The flexible skirt 31 will assist in containing concrete poured into the shuttering set. In the typical configuration such as illustrated in Figure 1 the flexible skirt 31 will tend to deform into engagement with the trench wall to inhibit upward flow of concrete around the lower leg 10.
The corner abutment of adj acent shuttering lengths may be achieved by cutting the abutting ends at an angle, e.g. 45 degrees on each to make a 90 degree abutment. Alternatively, and more advantageously, however, the vertical legs may be cut to length to abut at the corner whilst the horizontal leg of each shuttering length is cut shorter so at to terminate short of the corner, creating an opening in the horizontal surface at the corner. A corner piece is then fastened in place in the corner opening against which the jacks engage. This has the advantage that different corner angles can easily be achieve by simply use of different corner pieces which set the corner angle.
In use of the present invention a complete shuttering set is preformed, typically in a factory environment. The pre-forming will consist of cutting the lengths of material to size and assembling the various components. The components are then transported to site for final assembly. On site only the joints need be formed and these joints can be formed quickly and accurately because all the components needed have been pre-cut and substantially pre-assembled before arrival on site. Once the shuttering set has been fully assembled it is located in the required position. If it is used to form the foundation of an extension to an existing building it will be secured to the wall 32 of the host building 33 using conventional fixings. Once the shuttering set has been secured to the building the jacks 5 will be positioned and adjusted to level the shuttering set. Using jacks of the type described above levelling is easily effected by placing a suitable spanner on the upper nut 24 and rotating it to raise or lower the support plate 22 associated with a particular jack.
Once the shuttering has been levelled and the concrete pour a damp-proof course may be laid on the platform 3. Alternatively, if desired the damp-proof membrane may be laid to cover the platform 3 and the trench 2 before location of the shuttering set. In this alternative, once the damp-proof membrane has been installed and the shuttering correctly positioned, concrete is poured into the shuttering. The concrete will fill the trench 2. The initial flow of concrete will land on the sole plates 6 to hold them in position and thereby prevent the entire shuttering from "floating" as the concrete level rises. In practice, the concrete will be suitably compacted (for example by vibration) to complete fill the shuttering up to the level of the top edge of the upper vertical leg 12. As a result, the concrete will be contained at least in part by the lower vertical leg 10 and the upper vertical leg 12 and the concrete will underlie and support the horizontal legs 11 and 30. If desired, holes may be provided through the horizontal legs 11 and/or 30 to vent any air pockets that may be formed during concrete compaction. The skirt 31 will prevent excessive flow of concrete upwardly along the outer side of the lower leg 10. Once the shuttering has been filled the concrete may be levelled using conventional techniques and cure will start.
Because the vulnerable edge regions of the concrete are, in use at the present invention, protected by the material of the shuttering set it is believed that it will not be necessary to wait for a high level of cure before foundation walls can be constructed. Typically, even with a standard concrete mix, work on building the foundation walls can start within a few hours of pouring the concrete - certainly on the same working day.
The foundation walls are constructed on the horizontal leg 11 and, if present, on the horizontal leg 30. When the wall is constructed on the horizontal leg 11 the outer edge of the horizontal leg (i.e. at the juncture with the vertical leg 10) is used by the bricklayer as a guide for the position of the base course. Because the shuttering set has been factory produced and precisely formed no onsite checking or layout is necessary for the bricklayer - he can simply start laying his bricks on the horizontal leg 30 using the outer edge thereof as a guideline. Similarly, if an inner leaf is to be constructed it can be constructed either on the horizontal leg 11 if this is wide enough or on the horizontal leg 30. Once a suitable number of courses of bricks or blocks have been laid the remaining structure, which may for example be a pre-fabricated structure such as a conservatory, or a site constructed structure of for example brick or block, can be built atop the existing foundation walls.

Claims

A method for providing a foundation for a building comprising the steps of: pre-forming a shuttering set (4) so that in transverse cross-section the shuttering set (4) defines a vertical leg (10) for retaining concrete and a horizontal leg (11) that extends inwardly of the building from the top of the vertical leg (10) so that it is, in use, supported by the concrete retained by the vertical leg (10); positioning the shuttering set (4) at a use location; levelling the shuttering set (4); pouring the concrete into the shuttering set (4) to be at least partly retained by the vertical leg (10) and to underlie and provide support for the horizontal leg (11); allowing the concrete to at least partially cure; and constructing a wall on the horizontal leg (11) aligned with a guide provided by the horizontal leg (11).
A method according to claim 1, wherein the guide is provided by an outer edges of the horizontal leg (11) where it joins the vertical leg (10).
A method according to claim 1 or claim 2, wherein the shuttering set (4) is supported in position on a plurality of height adjustable struts (5), the step of levelling the shuttering set (4) comprising adjusting the height of the struts (5).
An apparatus for carrying out the method of the invention, the apparatus comprising a pre-formed shuttering set (4) that, in transverse cross-section, defines a vertical leg (10) for retaining concrete and a horizontal leg (11) that extends inwardly of the building from the top of the vertical leg (10).
An apparatus according to claim 4, further including a plurality of height adjustable struts (5) which, in use, engage between the ground and the shuttering set (4) in order to support the shuttering set (4) in position.
A method according to claim 3 or an apparatus according to claim 5, wherein each strut (5) has a sole plate (6) at its lower end which rest against the ground, which sole plate (6), in use, is covered by the concrete during filing so as to restrain the shuttering set (4) from floating as the concrete level rises.
A method according to any of claims 1 to 3 or 6 or an apparatus according to any of claims 4 to 6, wherein diagonal bracing bars (14) are attached to the shuttering set (4) in order to brace the structure.
A method according to any of claims 1 to 3, 6 or 7 or an apparatus according to any of claims 4 to 7, wherein the shuttering set (4) includes a second vertical leg (12) that extends upwardly from the inner edge of the horizontal leg (11) to retain concrete so that the finished surface of the concrete is above the level of the horizontal leg (11).
A method or an apparatus according to claim 8, wherein a second horizontal leg (30) extends inwardly of the building from the top edge of the second vertical leg (12) to provide a surface on which an inner leaf of a cavity wall may be constructed.
A method or apparatus according to claim 8, wherein the first horizontal leg (11) is wide enough to accommodate, in use, both the inner and outer leaf of the required wall, the inner leaf being constructed at a pre-determined spacing from the outer leaf or utilising a second guide provided by the shuttering set (4).