GB2327688A

GB2327688A - Floor with integral ground beams

Info

Publication number: GB2327688A
Application number: GB9715926A
Authority: GB
Inventors: John Joseph Freeman; Andrew William Leask
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-29
Filing date: 1997-07-29
Publication date: 1999-02-03
Also published as: GB9715926D0

Abstract

A building structure comprises a floor assembly (10) comprising a floor slab (12) and depending integral ground beams (14). An insulation layer (20) is fixed to the floor slab (12) and a water proof membrane (22) is affixed to the insulation layer (20). The floor assemblies (10) are supported on pile caps (26) of piles (24). Support blocks (16) are provided on the base of the ground beams (14) which are capable of being machined to ensure precise thickness of the floor assembly (10) where the beams are supported by the piles (24), (26). The pile caps (26) are levelled with respect to each other by a levelling plate (28) including three levelling screws acting on the top of each pile cap (26) and subsequently supported by a grout layer (34).

Description

INTEGRATED BUILDING STRUCTURE This invention relates to a building structure and also to a method of forming a building structure.

Our co-pending application number 9605763 describes and claims a method of forming a building structure, the method comprising pre-fabricating a plurality of wall assemblies and pre-fabricating a plurality of floor assemblies by moulding one component of each assembly from a structural material, to one face of said one component securing an arrangement comprising a liquid impermeable material sheet and an insulation material, preparing a foundation for the building structure on site, erecting the pre-fabricated wall and floor assemblies on the foundation, and securing adjacent assemblies together with the respective material sheets being liquid sealed together, whereby to form the building structure.

Such an arrangement provides for very effective building constructions, but it has been discovered t the alternatives of traditional trench foundations on the one hand and pile foundations on the other, which latter option requires the provision of ground beams on the pile caps, renders the system less attractive to employ. This is because the use of piles can be rather an expensive option, given the present methods of application, and therefore is only usually employed in ground conditions which prevent traditional trench foundations being employed. Having thus to decide which foundation method to employ makes the whole process more complicated and difficult to calculate as to cost-effectiveness. Indeed, ground surveys to establish ground conditions are themselves costly exercises.

It is therefore an object of the present invention to provide a building structure and a method of construction which does not suffer from, at least mitigates, the aforementioned problems. In this respect the invention seeks to provide a means of reducing the effective cost of pile foundations so that it becomes the sole and automatic choice in all or most circumstances.

This, in itself, eliminates, at least for this purpose, the need for, and hence the cost of, ground surveys.

In accordance with the present invention there is provided a building structure comprising: a foundation of piles; and a pre-fabricated floor assembly comprising a floor member and at least two spaced integral ground beams, the ground beams being supported on the piles.

The term "pile" as used herein is to be taken to include within its ambit a "cone" which is sometimes used in place of a pile where ground conditions are better and do not require a full pile.

Preferably the piles include levelling means comprising: a levelling plate and three levelling screws, whereby the plate can be levelled; and, non-shrinking support grout between the levelling plate and pile to support the plate on the pile after the plate has been levelled.

Preferably the plate has a hole into which grout in liquid form is poured to fill a space between the bottom of the plate and the top of the pile.

Preferably, the floor assembly comprises a moulding of structural material, such as concrete, a layer of insulation material and a water and/or gas impermeable layer.

Preferably the ground beams extend around the entire periphery of the floor assembly. The floor assembly may be any shape in plan, although typically would be rectangular.

The ground beams may include support blocks adapted to be supported on the piles, wherein the support blocks comprise: machineable material so that the thickness of the floor assembly where it is to be supported by the piles can be adjusted to within requisite tolerances to ensure even seating on the piles and a level floor.

Preferably the support blocks further comprise: material capable of fixation to said floor assembly and bonding to said piles. In this way tying of the piles together, which is a normal requirement when pile foundations are employed, is achieved. Laminated plastics is a suitable product for the support blocks although other materials, which are strong enough to support the vertical loads imposed and are capable of fging both to the piles and to the floor assembly for the purpose of tying the piles together, are doubtless known to the skilled person. Indeed while bonding of the support blocks to one or both of the piles and floor assembly is preferred, mechanical fixing should not be considered as excluded in appropriate circumstances.

The support blocks preferably further comprise: material providing a thermal break between the piles and floor assembly. The piles may have pile caps.

In another aspect, the present invention provides a method of forming a building structure comprising: driving at least three piles into the ground to an appropriate depth; levelling the piles; supporting a floor assembly on the piles, wherein the floor assembly comprises a floor member and at least two spaced integral ground beams, the beams being seated on the piles.

Preferably, the piles are levelled by means of levelling plates having three levelling screws, the method further comprising: levelling the plates on the piles and with respect to the other piles by appropriate adjustment of the levelling screws; and applying non-shrinking support grout between the piles and the levelling plates to support the plates on the piles and bond them thereto.

Preferably the grout is applied by pouring it in liquid form into a hole in the levelling plate. Prior to pouring, any gap between the plate and pile is preferably taped to prevent run out of grout and to ensure filling of the void between the pile and plate.

Preferably the floor assembly has blocks where the assembly is supported on the piles, the method further comprising: machining the blocks so that the thickness of the floor assembly is within requisite tolerance to ensure even seating on the piles and a level floor.

Alternatively, shims may be added to equalise thickness all around the floor assembly. In this event the shims are preferably mechanically fixed to the floor assembly. The shims may likewise be constructed from laminated plastics or similar material having essentially the same characteristics.

The term "level" as used herein means substantially horizontal, and "levelling" is used accordingly.

Thus the present invention provides a building construction and method of construction which employs piles on all types of ground, and this is rendered cost effective because, even on firm ground (which would otherwise be quite acceptable with trench foundations), the fact that the ground beams are integrated with the floor assembly means that no separate ground beam is required. Integrating the ground beam into the floor assembly does not significantly increase the cost of the floor assembly, so essentially an entire requirement for structural components (ie the ground beams) has been eradicated. In firm ground, it is only necessary to shorten the depth to which the piles are driven.

Conversely, in poor ground, the piles are driven deeper, there being little or no difference in final cost.

The present arrangement particularly benefits from the convenient pile levelling method described above, and which also permits the essential tying of pile heads together. The machineable blocks, most likely in the four corners of a rectangular floor assembly, enable the floor assembly to be arranged so that, when the blocks are supported on the piles, the floor assembly is level and there is even loading on all of the piles. The blocks may be made from a product sold under the trade name Tufnol (RTM).

If the block consists primarily of another material, such as sheet metal, for example, the block could also include a foamed polyurethane sheet as a thermal break.

In order to provide the tying between the piles, the blocks are fixed to the floor assembly, (probably mechanically, although bonding is an option), and to the pile heads. Bonding of the blocks to the pile heads is almost certainly the most convenient method of fixing, using an appropriate glue.

The integrity of the water impermeable layer is preserved at the points where it meets the blocks on the piles, and also by the application of suitable sealing material at the points where the floor assemblies meet the piles, between adjacent floor assemblies, and between the floor assemblies and walls upstanding thereon.

A further benefit of the present invention, is that, although it is particularly suited for application in the methods and structures described in our aforementioned co-pending application, it is not limited thereto.

Traditional building techniques can be employed on the structure defined by the present invention.

The invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a mid-side section through a floor assembly according to the present invention; Figure 2 is a section through a pile and pile cap employing a levelling plate in accordance with the present invention; and Figure 3 is a side section showing a complete building structure in accordance with the present invention.

In Figure 1, a floor assembly 10 comprises a floor slab 12 of essentially rectangular configuration and comprised of moulded concrete and provided around its periphery with a depending integral ground beam 14. In the corners of the floor slab 12 under the ground beams 14 is formed a support block 16 (see figure 3) secured by bonding or mechanical fixing to the underneath of the ground beam 14. The support block 16 comprises a machineable material, such as a laminated plastics material of the type made and sold by Tufnol Limited of Well Head Lane, Perry Bar, Birmingham, United Kingdom under the registered trade mark Tufnol. Such materials essentially comprise cotton fabric, asbestos, paper, glass fabric reinforced resins such as phenolic, epoxide, polyester and other plastics materials. Which particular grade of Tufnol (RTM) product is most suitable for the support blocks will be obvious to the man skilled in the art. Although Tufnol products are suitable, any alternative material having the requisite strength, temperature, durability, chemical resistance etc characteristics which are appropriate to the structural applications described herein could also be employed.

Where the support block 16 is a heat conductive material, such as metal, then it preferably also comprises a foamed polyurethane sheet 18 to serve as a thermal break (see Figure 3).

The box-like space defined by the floor slab 12, depending ground beams 14 and support blocks 16, is filled with rigid insulation material 20. Further insulation material 17 may extend under the ground beams 14. Finally, covering the underneath of the floor assembly 10 and extending between the bottoms of the ground beams 14, including the insulation material 17 and 16, is disposed a water impermeable sheet 22 forming a damp proof course.

Before delivery to the building site of the floor assemblies 10, the membrane 22 is peeled back from the support blocks 16 to enable the blocks 16 to be machined so as to ensure a constant thickness t of the floor assembly 10 at each corner. Alternatively, the membrane 22 is applied to the floor assembly after machining of the blocks 16. Even it could extend between the blocks and the ground beams. Indeed, the blocks may be machined before fixing to the ground beams, but then their requisite thickness needs to be calculated from the measured thickness at each corner of the precast floor slab and ground beams 12,14. Alternatively shims may be employed of various thickness to equalise the thickness t. The shims likewise may be constructed from Tufnol (RTM) material.

Turning to Figure 2, a pile 24 is shown. After being driven into the ground, the pile is capped with a pile cap 26. A levelling plate 28 is then placed on the pile cap, the plate comprising a plate of substantially the same size and shape as the top of the pile cap and three levelling screws 30 arranged in triangular formation and received in threaded bores (not shown) in the plate 28. When each pile 24 has been driven into the ground in their appropriate locations on the building site, each at approximately the same level, and after each has been capped with a pile cap 26, the levelling screws 30 are adjusted so that each plate 28 is rendered absolutely level (within permitted tolerances) not only with respect to themselves (ie the plate being itself level), but also with respect to each other plate on all the other piles on the site. Once the plates are all level, tape 32 is disposed around the plate and pile cap 26 to create a void 34 therebetween. Liquid grout is then poured through a central hole 36 in the plate 28 to fill the void 34. The grout supports the plate 28 on the pile cap 26 and bonds its thereto.

Turning now to Figure 3, two floor assemblies 10 are shown supported on a pile cap 26 of a pile 24. Grout 34 supports the levelling plate 28 which in turn supports the support blocks 16 of the two adjoining floor assemblies 10. The membranes 22 either pass over the levelling plates 28 and are disposed between the latter and the support blocks 16, or the membranes are trimmed around the pile caps 26 and sealed thereto with the use of an appropriate sealant. Sealant is also disposed between the two floor slabs 10.

The membrane 22 can only be permitted to pass under the blocks 16 if it is of a material capable of bonding to both the block and levelling plate 28 to provide the requisite tying of the pile caps 26 together. Since the membrane 22 is likely to comprise an elastomeric sheet, this criterion is unlikely to be met and therefore the blocks 16 will be directly bonded to the levelling plate 28, the membrane 22 simply being sealed with respect to the levelling plate 28. In any event, the grout 34 can be water impermeable.

Variations within the ambit of the present invention will of course be apparent to those skilled in the art without departing from the essence of the present invention.

Claims

1. A building structure comprising: a foundation of piles; and a pre-fabricated floor assembly comprising a floor member and at least two spaced integral ground beams, the ground beams being supported on the piles.

2. A building structure as claimed in claim 1, wherein the piles include levelling means comprising: a levelling plate and three levelling screws, whereby the plate can be levelled; and, support grout between the levelling plate and pile to support the plate on the pile after the plate has been levelled.

3. A building structure as claimed in claim 2, wherein the plate has a hole into which grout in liquid form is poured to fill a space between the bottom of the plate and the top of the pile.

4. A building structure as claimed in any preceding claim, wherein the floor assembly comprises a moulding of structural material, a layer of insulation material and a water impermeable layer.

5. A building structure as claimed in any preceding claim, wherein the ground beams extend around substantially the entire periphery of the floor assembly.

6. A building structure as claimed in any preceding claim, wherein the ground beams include support blocks adapted to be supported on the piles.

7. A building structure as claimed in claim 6, wherein the support blocks comprise: machineable material so that the thickness of the floor assembly where it is to be supported by the piles can be adjusted to within requisite tolerances to ensure even seating on the piles and a level floor.

8. A building structure as claimed in claim 6 or 7, wherein the support blocks comprise: material capable of fixing to said floor assembly and bonding to said piles.

9. A building structure as claimed in claim 6, 7 or 8, wherein the support blocks comprise: material providing a thermal break between the piles and floor assembly.

10. A support structure as claimed in claim 9, wherein said thermal break comprises a layer of polyurethane.

11. A building structure as claimed in any of claims 6 to 10, in which said support blocks comprise laminated plastics material.

12. A building structure as claimed in any preceding claim, wherein said floor assembly is substantially rectangular in plan.

13. A building structure as claimed in claim 12, wherein four piles support the floor assembly.

14. A building structure as claimed in any preceding claim, wherein each pile is capped with a pile cap.

15. A method of forming a building structure, the method comprising: driving at least three piles into the ground to an appropriate depth; levelling the piles; forming a floor assembly by casting from structural material a floor slab and at least two depending spaced integral ground beams; and supporting a floor assembly on the piles, the beams being seated on the piles.

16. A method as claimed in claim 15, wherein the piles are levelled by means of levelling plates having three levelling screws, the method further comprising: levelling the plates on the piles and with respect to the other piles by appropriate adjustment of the levelling screws; and applying support grout between the piles and levelling plates to support the plates on the piles.

17. A method as claimed in claim 16, wherein the grout is applied by pouring grout in liquid form into a hole in the levelling plate.

18. A method as claimed in claim 17, wherein, prior to pouring, any gap between the plate and pile is taped to prevent run out of grout and to ensure filling of the void between the pile and plate.

19. A method as claimed in any of claims 15 to 18, wherein the floor assembly has blocks on which the assembly is supported on the piles, the method further comprising: machining the blocks so that the thickness of the floor assembly is within requisite tolerance to ensure even seating on the piles and a level floor.

20. A method as claimed in any of claims 15 to 19, in which the floor assembly is bonded to the piles.

21. A building structure and method of assembling same substantially as hereinbefore described with reference to the drawings.