AU714754B2 - Post and pad foundation assembly - Google Patents

Description

WO 97/32089 PCT/NZ97/0020 -1- POST AND PAD FOUNDATION ASSEMBLY FIELD OF THE INVENTION This invention relates to the field of providing foundations for posts or piles extending from the ground, to support signs or to support constructions such as buildings.

BACKGROUND

The usual procedure for putting up a single-storey building (at least) involves the preparation of foundations embedded in the ground, to provide a platform on which the building is to be constructed. (One alternative is a concrete slab floor). About half of the foundations used in New Zealand comprise a mass of concrete of prescribed volume, poured into a hole dug into the ground down to a prescribed depth. The mass supports a vertical member or pile generally of wood, thrust into the concrete while it is moist (when it still is wet cement). "Prescribed" refers to various building codes.

Disadvantages of this process for making foundations include that a reasonable amount of wet cement has to be provided at the site, that lining up the piles requires a good deal of fiddling with temporary supporting struts, and that it can take seven days before the concrete around the piles has hardened enough for the stresses of further construction.

A common trend nowadays is to use high-density particle board as the floor, to prefabricate walls of houses and nail them over the floor, and the factors encouraging this speedy building are incompatible with waiting for the foundations to harden so in many cases the unhardened foundations may have been compromised by substantial stresses while still not hard. Furthermore, there may be a need to dispose of soil removed from holes.

Foundations having engagements concealed within the soil are known. For example one current practice when building a wall is to include a dogleg at the base of the foundations, by undercutting the soil to one or both sides at the base of a hole, so that should the wall tilt, soil has to be lifted on one side and compressed on the other.

Another practice for foundations comprises belling out the base of a hole, so that when filled with concrete the base is wider than the vertical column. Again, this involves the surrounding soil in movement of the structure whether uplift or lateral forces cause it. These practices have the disadvantages that at the time of pouring concrete, soil may move and compromise the structure, and that the curing time of the concrete can hold up a project.

OBJECT

It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages and/or more generally to provide an improved foundation assembly and method for providing a foundation using the improved assembly.

STATEMENT OF THE INVENTION *There is disclosed herein a foundation assembly; the assembly comprising a o* substantially rigid and generally disk-shaped foundation pad, and an elongate member or pile, and a fastening means, wherein the foundation pad has a thickness and a substantially flat lower surface, the lower surface of the pad having an area significantly greater than the cross-sectional area of the elongate member, and having a central aperture; the pad being capably when resting upon a prepared surface of bearing a load representing at least a part of the weight of a supported structure; the elongate member being capable of transmitting the load downward to the pad from the supported structure, the fastening means comprising an elongate, rigid shaft having a length of at least three times the thickness of the pad, the pad and the elongate member being held together by said shaft passing through the aperture of the pad and Adriven into a lower end of the elongate member so as to hold the pile firmly, but not Stightly against, the upper surface of the pad at a joint, so that in use the joint is capable of permitting the elongate member to pivot from side to side to a limited extent with reference to the pad if a substantial lateral force is applied to an upper portion of the elongate member, without loss of structural integrity of the foundation assembly.

Preferably the pad is a durable precast concrete pad, having a diameter which is at least greater than that of the elongate member or pile.

Preferably the fastening means comprises an elongated, rigid and durable shaft having a head sufficiently thickened to prevent its passage through the central aperture, and a length of about three times the thickness of the foundation pad or greater.

Preferably the foundation pad and a substantial portion of the pile are located in a hole upon a layer of particulate material, and lie at a level beneath the surface of the adjacent earth, and are covered with tamped or packed soil or like material, with a portion of the pile protruding from the soil, so that a structure may be at least in part supported upon the pile.

There is further disclosed herein a structure comprising a plurality of the above 2 described assemblies, having at least one row of at least two such foundation 20 assemblies, each row of foundation assemblies being connected together by a •horizontal member.

Preferably the structure has bracing means between the horizontal member and at least one ofthe elongate members.

:0 .i 25 Preferably the pile of each foundation assembly comprises a timber pile connected to a pre-cast concrete foundation pad by means of an elongate metal fastener.

There is further disclosed herein a method for providing a foundation using a foundation assembly as described above, the method comprising the steps of excavating a hole of at least a prescribed depth (as herein defined) in the ground, Nz providing a substantially flat load-bearing surface at the bottom of the hole, and placing the assembly upon the load-bearing surface, so that after placement the elongate member or pile of the assembly protrudes from the surface of the ground in a substantially vertical direction, and packing the hole with soil or like material, whereby in use lateral movement of the protruding portion of the elongate member or pile is resisted by the attachment to the foundation pad and by the soil or like material.

Preferably the load-bearing surface comprises a sand or other base layer of particulate material.

Preferably after placing the assembly in the hole soil removed from the hole is replaced over the pad and around the elongate member or pile and is tamped in place.

There is further disclosed herein a method for providing a unit of a ground-embedded foundation for supporting a building comprising the steps of excavating a hole at least a prescribed depth (as herein defined) in the ground, placing a base layer of particulate material at the bottom of the hole, placing upon the base layer an assembly as described above so that after placement a portion of the elongate member of the assembly protrudes from the surface of the ground in a substantially vertical direction, o 20 then back-filling the hole with an at least partially cohesive material and tamping the material down with some force.

o got *o.

Preferably the base layer of particulate material is sand.

Preferably the at least partially cohesive material is soil removed from the hole, i i 25 tamped into place.

Preferably the method includes the use of at least one aligned series of units as described above, the at least one series of units supporting horizontal support members of the base of the building upon the elongate members of the assemblies.

Preferably the method further includes the provision, between at least one horizontal support member and an underlying elongate member, of bracing means capable of reducing inadvertent sideways movement.

Preferably the bracing means comprises at least one metal plate affixing the elongate member to one or more horizontal beams supporting the structure.

Alternatively, the bracing means comprises one or more struts affixed at an angle between the elongate member and one or more horizontal beams.

20 a 3 o0 f3 (the next page is page 8) EDITORIAL NOTE NUMBER 17389/97 THIS SPECIFICATION DOES NOT CONTAIN PAGES 6 TO 7 WO 97/32089 PCT/NZ97/00020 -8-

DRAWINGS

The following is a description of a preferred form of the invention, given by way of example only, with reference to the accompanying diagrams.

Figure 1: is a section through a foundation pad plus pile assembly according to the present invention.

Figure 2: is an illustration of pad shapes and pad-pile attachment components of the present invention.

Figure 3: is an illustration of a foundation in place, showing resistance to vertical lifting by the present invention.

Figure 4: is an illustration showing the bond between the timber pile of the present invention and a horizontal bearer, using nail plates, Figure 5: is an illustration of a pile/bearer bond during application of an extreme lateral force.

Figure 6: is an illustration showing the bond between the timber pile of the present invention and a horizontal bearer, using a brace.

PREFERRED EMBODIMENT The examples to be described herein comprise ready-to-use concrete foundation pads incorporating certain improvements, together with (generally timber)vertical support members or piles, plus attachment means. The examples may be sold as components or in a ready-assembled state (referred to here as "an assembly").

In contrast to a conventional foundation comprised of a column of concrete or wood or the like occupying a substantially vertical hole in the ground, the substantially rigid foot or base of the invention engages with a greater volume of soil below, and also above it, in the manner of a deadman used sometimes to anchor a cable in the ground. The bearing surface of the concrete pad is significantly greater than the area of the vertical pile.

WO 97/32089 PCT/NZ97/00020 -9- An example pad has dimensions as follows: diameter 38 cm (this pad is circular), thickness 10 cm, central aperture 1.5 cm diameter, and forming the centre of a slot 5 cm in length on the base of the pad. The upper surface has a chalice-shaped enlargement 6 cm in diameter extending through about half the thickness of the pad. This widened hole is filled with a resilient "grommet" made of a degradation-resistant resilient material such as polyurethane. Currently we use a material with a Shore hardness of The grommet has a central aperture capable of admitting an about 1.2 cm diameter fixing pin which in the completed assembly passes from the base of the pad (preferably first passing through a washer) and is driven into the pith of a timber pile, to a depth of perhaps 20 cm. The pad is made of an approved grade of concrete and preferably samples from a batch are subjected to tests.

Reliance on engagement of the vertical member or pile with the surrounding soil (against side-to-side movement) is not considered by the inventors to be a desirable way to make a safe structure, because once a sideways force has been applied, the soil generally gives way and no longer holds the foundation firmly in place. By relying on the base with the soil over it as the means for maintaining the foundation in place, and not relying on the pile with the soil beside it to hold the building in place, the foundation assembly of this invention can better withstand and recover from lateral movement as might be caused by earthquakes or by strong winds, Test results given later support this view.

In other words the loadbearing (against the soil) functions are concentrated within the pad at the base, and not within that part of the pile in contact with the soil, in this invention. In contrast, a conventional poured concrete column relies rather more on contact with the sides of the column, and the weight of the poured mass.

The examples describe particular embodiments of this principle of foundation assembly construction.

EXAMPLE 1.

The base or pad (102 in Fig 1) comprises a generally hexagonal slab of concrete, cast in a former. A 100 mm thick pad satisfies the building standard NZS 3604 1990 (and in fact the assembly would satisfy that standard too). The pad has a defined usually central aperture, for attachment purposes, usually having an enlargement on one side. Preferred WO 97/32089 PCT/NZ97/00020 dimensions are: 100 mm thick x 300 mm diameter (or more).

A hexagonal slab (or a circular one) is suitable for dropping down a hole dug by the usual means a post-hole border and/or by hand, with a shovel or the like. Square or triangular slabs tend to catch the sides of the hole and bring down dirt, and have relatively little strength. Concrete has little strength when held in tension. In this application the usual weight of the structure being supported will provide a compression bias a sort of pre-stressing.

The concrete slab will have been made to a standard (such as thickness and also composition and method of manufacture) such that it will pass objective, prescribed tests for strength.

The aperture (Fig 2-201) through the slab may be a round hole, perhaps 10 -20 mm in diameter but more preferably it is a slot so that increased flexion can occur in one particular plane.

The aperture is enlarged usually on one side. The dimensions of the enlargement are intended to accommodate a rubber grommet or bored block of rubber 104 (intended to provide some give during lateral stresses that may be imposed on the completed foundation during subsequent seismic activity). Alternatively, urethane may be poured into a cavity cast into each base slab. With resilience provided here, the foundation can flex laterally without damage to any part. Of course the amount of resilience should be controlled so that the structure is inherently self-restoring. We usually prefer to place the resilient device on the upper side of the pad, that is, against the pile or post, although with a washer under the head of the shaft, they can be used up the other way.

The preferred attachment means comprises a mechanical fastener (Figs 1 and 2 -103) a very large nail or stud passed through the bored slab, through the aperture 201 in the concrete slab, and into the end of the timber pile 101 until the assembly so formed is tightly bound together. Hammering or pressing actions can be used to drive the fastener into the pile. It has been found that nailing into the end grain results in a good grip between the wood of the pile 101 and the large nail 102. Our preferred large nail 103 has a shaft diameter of about 9-12 mm, a length of 350 mm, and a head with an about (or at least) 25 mm diameter. A washer can be used under the head. There may well be WO 97/32089 PCT/NZ97/00020 -11 building code recommendations or minimum compliance measurements that have to be satisfied for the fastener. We prefer to cut a kind of thread 212 into the last 10 cm or so (207) of the sharp end of the nail, though optionally barbs 211 or grooves 207 may be used to assist with friction. (Surface "improvements" can be applied over the entire length). Some are shown in the enlargement of the fastener 210 at the bottom of Fig 2.

The barbs may be turned back like fish-hooks to further resist separation.

Preferred nails are made of steel with suitably long-lasting anti-corrosion coatings, such as several layers of hot-dip galvanising. Alternatively nails may be made of stainless steel. These nails are not in contact with other metallic objects. Strength over time is the main requirement. A desired nail lifetime (for most applications) is at least 80 years in wet soil; the lifetime of a well-preserved timber pile.

The timber pile itself 103 may be made of tanalised pine or other suitably durable wood; acceptable to building codes for use as a foundation pile. It is generally cut from the length of the timber so that the grain of the wood is oriented lengthways. It is usually at least 125 x 125 mm in section, or is round, and in general would be supplied in a range of fixed lengths so that after emplacement the builder can trim (shorten) an array of piles to a consistent level in order to bear horizontal beams bearers or the like.

Given that there is a requirement under the building codes to bury the pad in soil so that the base of the pad is at least 300 mm deep from the soil surface, a minimum pile length of about 700 mm is determined, and so the mechanical fastener length should be somewhat less than this (to avoid opening up the entire pile centre and to minimise the risk of it being sawn through when the array of piles is levelled off). Longer fasteners may be applicable for longer piles. In order to comply with current New Zealand building codes, these piles are typically placed 1-2 to 1.5 m apart. In fact. most measurements given herein are subject to building code requirements.

The preferred method of use is to select a pile 103 which is at least as long as the final required length, attach it by one end to a base 102, and place it in a hole of sufficient width and depth dug into the ground 301, onto a layer of 30 cm (approx minimum) of sand 303. The orientation of the pad slot and of the pile can be varied for accurate lining up. More sand is spaded in on top of the pad and around the cavity into the void at the sides of the pad. Once placed, the cavity is drenched with water so that the assembly is washed and grouted firmly into position. This resists movement that may WO 97/32089 PCT/NZ97/00020 -12result when the foundation is under load or when the hole is backfilled with excavated material 302. Backfilling is preferably done with some force, such as a tamping action.

It is difficult to specify the effectiveness of back-filling. Eventually, water and earthworm activity will help to "weld" the soil back into a solid form. (We have not indicated topsoil as a separate layer). After levelling the tops of a number of piles to a consistent height, bearers 305 may be attached by an approved attachment means.

Fig 3 shows a cross-section through a foundation pad and pile assembly, in place within a hole, backfilled with soil. 305 is a bearer supporting a built structure. 101 is a pile, attached (see Figs 4 and 6) to the bearer. 102 is a pad. It lies in sand 303 in the bottom of a hole, now filled with replaced soil 302. The dashed lines 304 show the approximate limits of the disturbance caused to surrounding soil in the event of the pile being pulled vertically from the hole, as might happen in the supported building was blown over by a hurricane. In other words this type of construction appears to ensure that a considerable weight of soil must be moved if the pile is pulled vertically.

Fig 4 shows a preferred means of attachment of bearers to piles. 501 is a bearer, 402 points to two joists, perpendicular to the bearer, for supporting a floor. 503/101 is a pile, and a number of nail plates 404, 505 are used to securely join the parts of the structure.

The nail plates can act as braces. These nail plates, made of 0.5 to 1 mm galvanised steel, are capable of tolerating a significant sideways force without failure or without much pulling of the nails (or screws in some cases). Thus they are compatible with the use of these pads for a force-resistant foundation construction.

Using a number of these pad/pile assemblies, one can adequately support an entire house. The support is typically rated as a short cantilevered pile system.

Fig 5, traced from a photograph taken during a test, shows the effect 500 of a strong force (FORCE) applied sideways from upper right against the floor joists and so against the bearer 501 of a test structure. Note the outwards deviation of the top 500 (shown as a slight deviation from parallel) of the pile 503. On removal of the pressure this pile returned substantially to its original position, and the nail plate 505 was substantially undisturbed. During the tests, the actual forces were measured, as were the first movements (when resilience of the grommet may play some part in recovery) and further "second" movement when some lateral compression of the soil in the hole may WO 97/32089 PCT/NZ97/00020 -13occur. We were pleased to observe that the structure recovered gracefully from a deflection large enough to cause the piles to be bent by (10) degrees from the vertical.

Another test (as shown in Fig 3) comprises application of an upwards force, attempting to pull the assembly up, out of the ground. A pad was pulled out of the ground by a controlled vertical force, shortly after being placed and backfilled with excavated material 302. The force required was about 800 kg and considerable ground disruption occurred to each side of the pile well beyond the perimeter of the hole itself. Heaving of the surrounding soil occurring approximately out as far as the dashed lines 304. This extensive involvement implies that the overall shape of the assembly a narrow vertical member and a wide disc-like foot tends to be held in well by soil. The resistance to lifting vertically appears to comprise its own weight) weight of adjacent soil, (3) friction) and some suction. The term "adjacent" is difficult to quantify. It would depend for example on the type of soil (clay is better than sand) and the extent of back-filling and tamping down that was done, and would improve over time as the soil settles down, It is almost certainly better than a typical prior-art concrete foundation which is effectively a column of concrete without a pronounced foot and for which the resistance to lifting vertically comprises its own weight) friction) and (3) suction. There will be a certain amount of adjacent soil involvement, probably not much. We recommend a hole depth of about 600 mm for general purposes, including areas with some risk of earthquakes, and 1200 mm deep holes for hurricane-prone areas.

Another bracing method is shown in Fig 6, where the construction of Fig 4 is further supported by means of an angled timber strut 601 affixed by suitable fasteners at each end. In this instance one could use nails or the like instead of nail plates.

ADVANTAGES and COMMERCIAL BENEFITS.

One principal advantage of this system over conventional poured-concrete methods is that the foundation pads can be placed, and the supporting structure can be built on top, without waiting for the usual 7 days curing time required if piles are footed in wet concrete poured into the hole. This can be a useful saving in time. If the seven day period is ignored, the concrete fails because it is stressed while only partially cured.

WO 97/32089 PCTINZ97/00020 -14- It appears that a structure using the invention as foundations is suitable for use in an earthquake-resistant environment; for although the foundations may be deflected by sideways motion of the earth, they are relatively resistant to permanent damage.

Superstructures may still fail in themselves, but at least the foundations are not so likely to fail as are prior-art concrete foundations.

It also implies that structures built with these assemblies as foundations are relatively hurricane resistant, (in hurricanes, sideways wind forces tend to laterally shift, and roll buildings over).

The survival of other building services such as water pipes (now usually in plastic) and electricity conduits is assisted if the foundations have a "self-restoration" action after external wind or seismic forces.

Commercial benefits in general include: Foundations can be made quickly and are ready for immediate use without concrete curing time delays.

Piles are held by themselves and will be substantially vertical if the hole bottom is level no struts required.

There is no need to provide wet cement on the site, because there is no requirement for concrete infill.

Nearly all of the material removed when digging foundation holes (or a trench) is put back.

Foundations are (relative to a concrete pour around a wooden pile) relatively hard to pull out of the ground.

Assemblies recover from sideways forces. (If a foundation based on a concrete pour around a wooden pile is forced sideways, the soil will become more compacted under compression and will not recover to the same extent.) The foundations could be re-used, if for example they had been used to support a garden shed, and the shed was later to be moved to some other position. They can be dug up and handled individually; whereas a poured concrete foundation is generally too heavy and unwieldy to handle.

In its simplest form a preferred foundation assembly has a timber pile attached to the WO 97/32089 PCT/NZ97/00020 upper surface of a wider pre-formed concrete pad by means of an axial transfixing shaft running from the lower surface of the slab. The pad has a recess facing the bottom of the pile, with a resilient grommet situated in the recess in contact with the base of the pile. The pad with pile attached is placed on a sand layer at the bottom of a dug hole and the hole is then filled with soil and tamped down to hold the foundation assembly in place. The resulting assembly has good resistance to deflection, loadbearing, and vertical uplift forces so becoming suitable for hurricane and earthquake-prone areas.

Single assemblies are suitable as a foundation for signposts and fence posts.

FURTHER VARIATIONS Assemblies tested to date are generally suitable for buildings as big as a house or a farm shed, or as small as a garden shed. Garden sheds, being not intended for habitation, are outside the New Zealand building codes. We expect to be able to scale up the dimensions (or the number) of the various parts of the assemblies in order to provide satisfactory foundations for larger buildings such as two-storey buildings.

Scaling down the structure, smaller pads can be used for decking, such as a deck joined to a house, or for sign posts and fenceposts. In this case, the item termed a "pile" is now a post of a desired height.

Other materials may be used. Generally any material has to satisfy immediate load-bearing criteria, and also has to maintain those criteria over a long period, such as 80 years.

A plastic foundation pad may be used. The material may be recycled terephthalates ("Mylar") as used in carbonated beverage containers, or polythenes from discarded milk bottles, or some other source of plastics material, which may be virgin rather than recycled. Fibre reinforcing, as with glass fibre, may be used. further stiffness may be provided by the use of strengthening ribs within a moderately thick pad. Alternatively, resilience may be provided as an innate property of this type of pad.

If pad weight is important, particularly during the early stages of settling, concrete including ironsand may be used, or the pad may be made of a metal slab; perhaps cast iron. Signposts or fence posts could be supported on a metal sheet.

WO 97/32089 PCT/NZ97/00020 -16- Piles could be made from metal pipe, particularly in areas where wood is in short supply. If resilience is provided at the pile/base junction, pile fracture is unlikely. A fixing means may comprise a bar across or near the base of the metal pile. Preferably the inside is filled with some space-occupying material in order to exclude water.

A stiffening collar may be placed about the pile at about the point where it emerges from the ground, thereby providing some support to the shaft of the pile. The stiffening collar may be constructed of some resilient material capable of absorbing sideways movement without giving way. Alternatively it may be poured concrete, simply poured into an incompletely backfilled hole. Alternatively it may be a rigid disk (perhaps of steel) designed to cut into the ground and develop friction if sideways movement is caused. Possibly even a lead/rubber composition may be used here for damping seismic movements.

Finally, it will be appreciated that various alterations and modifications may be made to the foregoing without departing from the scope of this invention as claimed.

Claims (12)

1. A foundation assembly; the assembly comprising a substantially rigid and generally disk-shaped foundation pad, and an elongate member or pile, and a fastening means, wherein the foundation pad has a thickness and a substantially flat lower surface, the lower surface of the pad having an area significantly greater than the cross- sectional area of the elongate member, and having a central aperture; the pad being capable when resting upon a prepared surface of bearing a load representing at least a part of the weight of a supported structure; the elongate member being capable of transmitting the load downward to the pad from the supported structure, the fastening means comprising an elongated, rigid shaft having a length of at least three times the thickness of the pad, the pad and the elongate member being held together by said shaft passing through the aperture of the pad and driven into a lower end of the elongate member so as to hold the pile firmly, but not tightly against, the upper surface of the pad at a joint, so that in use the joint is capable of permitting the elongate member to pivot from side to side to a limited extent with reference to the pad if a substantial lateral force is applied to an upper portion of the elongate member, without loss of structural integrity of the foundation assembly.

2. A foundation assembly as claimed in claim 1, wherein the pad is a durable precast ~concrete pad, having a diameter which is at least greater than that of the elongate member or pile. w:o 3. A foundation assembly as claimed in claim 1, wherein the fastening means comprises an elongated, rigid and durable shaft having a head sufficiently thickened to prevent its passage through the central aperture, and a length of about three times the thickness of the foundation pad or greater. S 4. A foundation assembly as claimed in either or both of claims 2 and 3 wherein the '.1foundation pad and a substantial portion of the pile are located in a hole upon a layer of particulate material, and lie at a level beneath the surface of the adjacent earth, and are SoS5 covered with tamped or packed soil or like material, with a portion of the pile protruding from the soil, so that a structure may be at least in part supported upon the 1kHe. 3 q '9 8 309qclmn98 A structure comprising a plurality of foundation assemblies as claimed in claim 4, having at least one row of at least two such foundation assemblies, each row of foundation assemblies being connected together by a horizontal member.

6. A structure as claimed in claim 5, having bracing means between the horizontal member and at least one of the elongate members.

7. A structure as claimed in claim 6, wherein the pile of each foundation assembly comprises a timber pile connected to a pre-cast concrete foundation pad by means of an elongate metal fastener.

8. A method for providing a foundation using a foundation assembly as claimed in either or both of claims 2 and 3, comprising the steps of excavating a hole of at least a prescribed depth (as herein defined) in the ground, providing a substantially flat load- bearing surface at the bottom of the hole, and placing the assembly upon the load- bearing surface, so that after placement the elongate member or pile of the assembly protrudes from the surface of the ground in a substantially vertical direction, and packing the hole with soil or like material, whereby in use lateral movement of the protruding portion of the elongate member or pile is resisted by the attachment to the foundation pad and by the soil or like material.

9. A method as claimed in claim 8, wherein the load-bearing surface comprises a sand or other base layer of particulate material.

10. A method as claimed in claim 9, wherein after placing the assembly in the hole soil too removed from the hole is replaced over the pad and around the elongate member or pile and is tamped in place. o 11. A method for providing a foundation substantially as herein described with reference S0 to any one of the accompanying drawings. o. 12. A foundation assembly substantially as herein described with reference to any one of the accompanying drawings. Ce t °o 13. A structure comprising a plurality of foundation assemblies substantially as herein described with reference to any one of the accompanying drawings. 19

14. A method for providing a unit of a ground-embedded foundation for supporting a building comprising the steps of excavating a hole of at least a prescribed depth (as herein defined) in the ground, placing a base layer of particulate material at the bottom of the hole, placing upon the base layer an assembly as claimed in either or both of claims 2 and 3 so that after placement a portion of the elongate member of the assembly protrudes from the surface of the ground in a substantially vertical direction, then back-filling the hole with an at least partially cohesive material and tamping the material down with some force. A method as claimed in claim 14 wherein the base layer of particulate material is sand.

16. A method as claimed in claim 14 wherein the at least partially cohesive material is soil removed from the hole, tamped into place.

17. A method as claimed in claim 14 including the use of at least one aligned series of units as claimed in claim 5, the at least one series of units supporting horizontal support members of the base of the building upon the elongate members of the assemblies.

18. A method as claimed in claim 17; the method further including the provision, between at least one horizontal support member and an underlying elongate member, of bracing means capable of reducing inadvertent sideways movement. 00 o "19. A method as claimed in claim 18 wherein the bracing means comprises at least one metal plate affixing the elongate member to one or more horizontal beams supporting Othe structure.

20. A method as claimed in claim 18 wherein the bracing means comprises one or more o$ *struts affixed at an angle between the elongate member and one or more horizontal 0 0 beams. 8309qclm.n98