AU2007200925A1 - Building Construction System - Google Patents

Description

BUILDING CONSTRUCTION

SYSTEM

FIELD OF THE INVENTION This invention relates to a building construction system. More particularly. this invention relates* to a method of construction and to various structures.

c BACKGROUND TO THE INVENTION The competitive nature of the building industry has led to a need for cost effective methods Sof construction. As is well known, cost effectiveness is achieved by simplicity and efficiency in construction. A major component of the cost of building is labour, both skilled and unskilled. This is particularly so in first world countries such as Australia and the United States.

Prefabricated components such as frames and panels and even fully prefabricated structures in knockdown form have been used. The aim of these concepts is to achieve a structure that can be rapidly assembled on site by non-skilled labour.

These concepts have faced a number of difficulties. One particular difficulty is the fact that building standards vary considerably throughout regional and geographic areas. An example of this is wind-loading standards for roofing and wall structures which vary significantly throughout a country like Australia. These standards include specific requirements in cyclone rated areas.

The problem with the present concepts is that they are generally incapable of complying with such a variation in requirements.

Applicant had previously developed a steel reinforced concrete walled construction system. Fibre reinforced cement sheet is supported on a steel-framed wall to define a.

substrate for sprayed concrete. This system was a development of a method for forming screeded reinforced concrete walls in underground excavations such as car parks.

Australian Patent No. 708031 requires skilled labour to erect steel wall framing on site.

This entails substantial design work depending upon building code requirements for differing geographic regions. Furthermore, the flexibility of the structure during application of the sprayed concrete induces a degree of thixotropy to the applied layer. in some cases C causing it to flow downwardly on the fibre cement sheeting support substrate.

I Applicant submits that the invention as claimed in the appended claims addresses the C problems set out above.

SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a method of constructing a panel assembly for a building structure, the method including the steps of: erecting a support frame on a substrate; mounting structural sheeting on the support frame so that the support frame and structural sheeting together define a zone in which cementitious material is to be set; positioning at least one post-tensioning member in the zone to span the zone; applying a cementitious, settable material to an inner surface of the structural sheeting to fill the zone with the settable material, so that the, or each, post tensioning member extends through the settable material; allowing the cementitious material to set to a predetermined extent: and setting up a predetermined tension in the post-tensioning member once the cementitious material has set to said predetermined extent.

The step of erecting the support frame on the substrate may include the steps of positioning a pair of spaced support members on the substrate and fastening a bridging member to free ends of the pair of spaced support members.

The method may include the step of mounting formwork on the support frame so that the zone is bounded by the structural sheeting, the support frame and the formwork and introducing the cementitious material into the zone to cast the cementitious material in-situ.

The formwork may be removed once the cementitious material has set.

t- The method may include the step of spraying the cementitious material into the zone. In 0 this case, the method may include the step of removably securing transverse support members to the structural sheeting to support the structural sheeting while the cementitious material is sprayed on to the structural sheet.

O Preferably. at least two vertically spaced support members are removably secured between opposite ends of the support frame.

0 The method may include the step of positioning steel reinforcing in the zone prior to c applying the settable cementitious material.

C According to a second aspect of the invention, there is provided a method of constructing a wall assembly, the method including the steps of: erecting a number of support frames on a substrate; mounting structural sheeting on the support frame so that the structural sheeting and the support frames define zones in which cementitious material is to be set; positioning at least one post-tensioning member in each zone to span the respective zone; applying a cementitious, settable material to an inner surface of the structural sheeting to fill the zones with the settable material, so that the, or each, post tensioning member extends through the settable material; allowing the cementitious material to set to a predetermined extent; and setting up a predetermined tension in the post-tensioning members once the cementitious material has set to said predetermined extent.

The method may include the steps of: initially applying the cementitious, settable material to alternate zones; allowing the material in said alternate zones to at least partially set; applying the settable material to remaining zones; and using the at least partially set material in the alternate zones as a guide for screeding the material in the remaining zones.

According to a third aspect of the invention, there is provided a method of constructing a building, such as a dwelling structure, which includes the step of constructing a number of wall assemblies in accordance with the method as described above, in predetermined locations, on a base.

According to a fourth aspect of the invention, there is provided a method of constructing a N retaining wall assembly. the method including the steps of: positioning a layer of sheet piling against soil to be retained; Spositioning at least one post-tensioning member adjacent the layer of sheet piling; Sapplying a layer of cementitious material to the sheet piling to cover the, or each, C post tensioning member; Nallowing the cementitious material to at least partially set; and applying a predetermined tension to the, or each, post tensioning member.

The step of applying the sheet piling may comprise the step of applying corrugated sheet piling.

The method may include the step of positioning vertical reinforcing bars in at least a number of the corrugations of the sheet piling before applying the layer of cementitious material.

The method may include the step of using formwork to cast the layer of cementitious material in situ on the sheet piling.

Instead, the method may include the step of spraying the cementitious material on to the sheet piling.

The invention extends to a method of constructing a basement structure which includes the step of constructing at least one retaining wall assembly in accordance with the method as claimed in claim 11 on a basement slab.

According to a fifth aspect of the invention, there is provided a panel assembly for a building structure, the panel assembly including a support frame that is mountable on a substrate; structural sheeting positioned on the support frame so that the support frame and the structural sheeting define a zone for a cementitious material; t- a layer of cementitious material positioned against the structural sheeting to fill the 0 zone: and at least one post-tensioning member that extends through the layer of cementitious material with a predetermined tension applied to the member.

The panel assembly may include a pair of vertically spaced post-tensioning members that extend through the layer of cementitious material.

The cementitious material may be in the form of a concrete that contains a polypropylene fibre mesh.

The structural sheeting may be of compressed fibre cement (CFC).

The invention extends to a wall assembly for a building structure, the wall assembly including at least one panel assembly as described above.

According to a sixth aspect of the invention, there is provided a retaining wall assembly that includes a layer of sheet piling that is positioned against soil to be retained; a layer of cementitious material applied to the layer of sheet piling; and at least one post-tensioning member that extends through the layer of cementitious material and is tensioned to a predetermined extent.

The layer of sheet piling may comprise corrugated panels of sheet piling.

The invention is now described, by way of example, with reference to the accompanying drawings. The following description is illustrative only and is not intended to limit the scope of the invention described in the preceding paragraphs.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: t- Figure 1 shows an external view of a wall assembly constructed in accordance with the O invention.

Figure 2 shows an external view of the wall assembly in a partly constructed condition.

O Figure 3 shows an enlarged view of a corner abutment of adjacent wall assemblies constructed in accordance with the invention.

0 Figure 4 shows an enlarged part cross sectional view through a wall assembly constructed C in accordance with the invention.

N Figure 5 shows a plan view of a dwelling structure, in accordance with the invention.

Figure 6 shows a roof plan of the dwelling structure.

Figure 7 shows a floor slab plan of the dwelling structure.

Figure 8 shows a detailed view of an edge beam of the dwelling structure taken through A- A in Figure 7.

Figure 9 shows a detailed view of an internal beam of the dwelling structure taken through B-B in Figure 7.

Figure 10 shows a detailed view of an isolation joint of the dwelling structure taken through E-E in Figure 7.

Figure 11 shows a detailed view of an edge beam taken through F-F in Figure 7.

Figure 12 shows a detailed view of an internal beam taken through C-C in Figure 7.

Figure 13 shows a detailed view of an edge beam taken through D-D in Figure 7.

Figure 14 shows a detailed view of a brick pier pad footing taken through G-G in Figure 7.

Figure 15 shows a truss to wall connection assembly of the dwelling structure.

SFigure 16 shows an alternative truss to wall connection assembly of the dwelling structure.

0 C Figure 17 shows a wall section of the dwelling structure.

n Figure 18 shows a corner assembly of the dwelling structure.

Figure 19 shows a detailed view of the part X in Figure 17.

Figure 20 shows a corner detail of the part Z in Figure 7.

Figure 21 shows a wall elevation of the dwelling structure.

Figure 22 shows a detail of the part Y in Figure 7.

Figure 23 shows a shoring and retaining wall section taken through H-H in Figure 24 of a basement structure of the invention.

Figure 24 shows a floor slab and basement wall layout plan of the basement structure.

Figure 25 shows an external corner detail of the part V in Figure 24.

Figure 26 shows an internal corner detail of the part W in Figure 24.

DETAILED DESCRIPTION OF THE INVENTION In Figures 1 and 2, reference numeral 1 generally indicates a wall assembly of a dwelling structure, in accordance with the invention.

The wall assembly 1 includes a plurality of abutting frame elements 2. The frame elements 2 typically measure between about 1200 mm wide and 2400 mm high with a 600 mm spacing between upright wall joists 3. A half size frame element 2a provides some dimensional freedom in the wall assembly 1.

The frame elements 2 include the upright wall joists 3, upper transverse members 4 and 0 C lower transverse members 5. These are all fabricated from a light gauge U-section metal Schannel. Preferably. the frame elements 2 comprise identical simple rectangular panels with welded joints.

0 Door and window openings 6, 7, respectively, may be prefabricated during fabrication of C the frame elements 2. Instead, these may be cut out of the wall frame where adjacent O frame elements 2 are coupled. Such coupling is typically by self-drilling, self-tapping C screws extending between abutting wall joists 3 of adjacent frame elements 2. Fabricated O or prefabricated window and doorframes 8, 9, respectively, are secured in the openings 6, C 7.

If the wall assembly 1 is erected on a raft slab 10, starter bars 11 extend from the slab into an interior wall cavity via the lower transverse members 5, which can be in the form of base plates 5. The starter bars 11 can be wired or coupled to upright reinforcing bars 12.

The reinforcing bars 12 can be wired to transverse reinforcing bars 13.

As shown in Figure 2, the frame elements 2, in the form of outer side panels 2, 2(a) are sheeted with fibre reinforced cement sheets 16 to create a formwork on one side of the wall assembly 1.

Conduits 21 are located in the wall cavity, as shown in Figure 1. The conduits 21 house post-tensioning cables 15. Conduits 30 that extend upwardly from the slab 10 are also located in the wall cavity. These are water conduits. It will be appreciated that other conduits for services such as electrical power, communication, etc can also be positioned in the wall cavity.

Panels 17 of low-density material such as polystyrene are also shown in Figure 1. The purpose of these is described below.

Initially, each alternate panel 2 is sprayed with a flowable cementitious grout. The grouted panels 2 are screeded to a flat surface using the exposed edges of the frame elements as screed guides. When the grout has cured to a sufficient degree, adjacent wall cavities are sprayed with grout and screeded to provide a substantially continuous wall surface with O the structural and reinforcing members and utilities encapsulated within the wall between C opposite sides as shown in Figure 2. After the cementitious grout in the wall cavities has hardened to a sufficient degree, the post-tensioning cables 15 are tensioned with a hydraulic tensioner and a free end 15a of the cables are severed adjacent the tension Scolletsor like tension anchors 18.

c Figure 3 shows that the inner edges of adjacent wall structures 1, 1 a abut to form a cavity 0 with an inside corner in which the ends of the post tensioning cables 15 are located. These c can also be in the form of rods. Exposed ends 19 of horizontal reinforcing bars 13 are 0 located in this cavity The screeded wall surface can then be finished in conventional manner by painting or with some other decorative/protective finish.

The basic structure and structural method have been described above for the sake of simplicity. It should be understood that whilst the outer wall surfaces are described as sheeted with fibre reinforced cement and the inner wall surfaces are described as screeded cementitious grout, the reverse may apply or the inside surface may also comprise fibre cement sheeting.

While only a single wall assembly 1 has been described, it will readily be apparent that the remainder of the dwelling structure embodied similar structural and procedural features including inner wall structures whether load-bearing or not.

Figure 3 shows an enlarged view of the junction of wall assemblies 1, 1 a at a corner of the dwelling structure.

Each end wall is left exposed to form a bearing surface for a hydraulic tensioner (not shown) to tension cables 15 before locking in respective tension anchors 18 on or in the end walls 1, la.

Figure 3 also shows in greater detail how adjacent cables 1,1la are locked together by O reinforcing bars 13 (only one of which is shown) extending between the adjacent walls with San exposed corner 19.

After severing the free ends of cables 15, the open inside corner cavity 20 is filled with O grout either by boxing up the cavity and introducing grout from the top or by spraying the grout and screeding the exposed surfaces using the surfaces of wall 1. 1 a as a screed C-i guide.

c-i Figure 4 also shows a number of important aspects of the invention.

c-i In particular, Figure 4 shows an enlarged cross sectional view through a wall under construction with a vertical joist or stud 3 forming part of the frame element 2 to which the fibre cement sheeting 16 is attached. A post tensioning cable 15 is suitably located in a conduit 21 extending through aligned apertures 22 in studs 3. Form foam panels are shown secured by adhesive or the like to the inner surface of the sheeting 16.

Studs or wall joists are chosen to suit a minimal load requirement for, for example, a nonload bearing inner wall and as such may be from 50 mm to 65 mm in depth. Where a load bearing or outer wall is calculated to require an overall thickness of say 90 mm between the inner and outer surfaces, a spacer 24 in the form of a thin metal strip is secured between abutting studs 3 of adjacent wall frame elements by self drilling/tapping screws which also couple the frame elements. The strip is adjustable to provide an increase in interior wall cavity of say 25mm from 65mm to the required 90mm. Depending on the structural characteristics required of the wall, the thickness of the foam panel may be increased up to 35 mm to reduce the volume of cementitious grout and thus the material cost of the wall.

The spacers 24 are positioned at each junction of the frame elements and act as a spacer for internal removable formwork (not shown) or as screed guides if the cementitious grout is sprayed into the wall cavities.

Preferably, the screws 25 are inserted from the inner faces of the same frame element such that after each alternate frame element has been sprayed with grout and screeded,

II

the strips 24 are then removed by exposed screw heads in the unsprayed alternate wall O :-cavities, the screeded wall surfaces of adjacent grouted frame elements now forming screed guides for the subsequently sprayed alternate wall cavities.

Before commencing spraying of the grout against the inner surface of the sheeting 16.

o elongated reinforcing members 26 such as corrugated steel railing or soldier piles for lightweight steel sheet piling are secured transversely of the structure on the outer face of C sheeting 16. Conveniently, the reinforcing members are clamped against the face of 0 sheeting 16 by rod clamps 27, hooked at one end around transverse reinforcing bars 13 C and secured via an aperture in member 26 by a wing nut 28 or the like.

C When alternate wall frame elements are sprayed with grout, the reinforcing members, typically two or three members vertically spaced, prevent the flexureof sheeting 16 which can induce thixotropy in the layer of sprayed grout or otherwise cause it to flow downwardly due to mechanical vibration.

After grouting of the wall is complete, the reinforcing members 26 are removed and the free end of each rod clamp is broken off by means of a notch located just below the outer surface sheeting 16.

In Figures 5 to 7, reference numeral 40 generally indicates a dwelling structure in accordance with the invention.

The dwelling structure 40 includes a number of wall assemblies 42, also in accordance with the invention and the result of a method of construction in accordance with the invention.

As can be seen in the drawings, the wall assemblies 42 are positioned on a floor slab 44 (Figure 7) to define the outer walls 46 of the dwelling structure 40. Internal walls 48 of the dwelling structure 40 are typical stud walls.

In this particular example, the outer walls 46, the internal walls 48 and the slab 44 of the dwelling structure 40 define a pair of bedrooms 50, a court 52, a patio 54 a dining and living area 56, a study 58 and a garage A roof structure 62 of the dwelling structure 40 is shown in Figure 6. The roof structure 62 0 C includes timber roof trusses 64 that are mounted on the wall assemblies 42 in a conventional manner. As can be seen in Figure 6, an entrance side of the garage includes 200 mm thick piers that support a steel beam 66, so that the steel beam 66 spans O an entrance to the garage C A plan of the floor slab 44 is shown in Figure 7. The floor slab 44 is of concrete. Cement of O the concrete is type normal-class portland cement. A maximum size of coarse 0 C aggregate in the concrete is 20 mm. Any beams, slabs, footings, columns, and walls will O have a slump of 80 mm.

0 The concrete of the slab 44 is reinforced throughout with one layer of RF72 fabric, with a lap of 300 mm.

Figure 8 shows a section through A-A in Figure 7. In particular, Figure 8 shows an edge beam detail of the dwelling structure 40. The detail shows one of the outer walls 46, positioned on the slab 44. The outer wall 46 is in the form of the wall assembly 42, in accordance with the invention. At this location, the slab 44 has a 350 mm wide edge beam 68 that supports the wall assembly 42. The layer of reinforcing is indicated at 70. A vapour barrier 72 is positioned intermediate the slab 44 and the ground.

The wall assembly 42 includes starter reinforcing bars 74. The layer 70 of reinforcing extends into the edge beam 68. Lower ends of the starter reinforcing bars 74 are connected to the layer 70 in the edge beam 68. The wall assembly 42 also includes vertical reinforcing bars 76 that are connected to the starter bars 74.

The wall assembly 42 includes internally positioned sheets 78 of compressed fibre cement

(CFC).

Figure 9 shows a section through B-B in Figure 7. In particular, Figure 9 shows an internal beam detail of the dwelling structure 40. The slab 44 includes a number of internal beams that are 300 mm wide and 30 mm deep, measured from a surface of the slab 44. The slab 44 is positioned on a blinding layer 82, with the internal beams 80 extending through 0 the blinding layer 82.

Figure 10 shows an isolation joint detail of the dwelling structure 40. This drawing simply indicates a seal 84 that is positioned between the edge beam 68 and a floor slab 86 of the Scourt 52.

C Figure 11 shows a further edge beam detail. In this drawing, an edge beam 86 of the court 52 is shown.

Figure 12 shows an internal beam detail. In this drawing, one of the wall assemblies 42 is c positioned on one of the internal beams 80. In this example, the wall assembly 42 serves to separate the living area 56 and garage 60. In this application, the internal beam 80 has a width of 350 mm. As can be seen, the slab 44 steps to make the transition from the living area 56 to the garage Figure 13 shows an edge beam detail at an entrance to the garage Figure 14 shows a brick pier pad footing 88 at a corner of the patio 54. The footing 88 includes a bricked support 90 positioned on a concrete pad 94 beneath the slab 44 defining the patio 54.

A reinforcing bar 92 extends through the bricked support 90 and into the concrete pad 94.

A reinforcing member 96 is positioned in the concrete pad 94. The reinforcing bar 92 is connected to the reinforcing member 96. A compressible filler 98 is positioned between the slab 44 and the bricked support Figure 15 shows a truss-to-wall connection of the dwelling structure 40. As can be seen, the truss 64 is fast with a framing anchor 100. Two of the framing anchors 100 are bolted to a top edge 102 of the wall assembly 42 with galvanised bolts 104.

Figure 16 shows an alternative truss-to-wall connection. In this example, the truss 64 is fast with a saddle bracket 106. The saddle brackets 106 are bolted to the wall assembly 42 with galvanised bolts 108.

O Figure 17 shows a detailed wall section of the wall assembly 42. The wall assembly 42 0 c includes a number of panel assemblies 124. Each panel assembly includes CFC sheeting t 110 that is positioned on the slab to define a casting support for a concrete mix to be cast in a zone 118 defined by the sheeting 110 and a top plate 114 that is fast with an upper o edge Qf the sheeting 110. The CFC sheeting 110 can be in the region of 6 mm thick.

C A number of starter bars 112 extend from an edge beam 116 into the zone 118. The wall O assembly 42 includes a number of vertical reinforcing bars 120 positioned in the zone 118.

c The vertical reinforcing bars 120 are connected between the starter bars 112 and O galvanised bolts 122 that extend through the top plate 114 into the zone 118.

0 Each panel assembly 109 includes a pair of horizontal, spaced post-tensioning bars 126.

Each post-tensioning bar 126 is sheathed in a PVC conduit 128.

Concrete received in the zone 118 includes 40Mpa Polypropylene Fibremesh with a 5 to 7 mm aggregate size. The concrete can either be sprayed into the zone or cast in situ. Once the concrete has set to a predetermined extent, the bars 126 are pre-tensioned to a predetermined extent. In one particular example, the bars 126 have a diameter of 12mm, the reinforcing bars 120 have a diameter of 12mm and the concrete thickness is 90mm. In this example, the reinforcing bars 126 are pre-tensioned to Figure 19 shows a detailed view of a styrene blockout 130 that is positioned on an inner surface of the CFC sheeting 110. The styrene blockout 130 ensures that a space is defined in the concrete to allow for services such as power points.

Figure 20 shows a corner detail of the dwelling structure 40. In particular, Figure 20 shows a pair of wall assemblies 42 connected together. A vertical bar 132 is positioned at a junction between a pair of the wall assemblies 42. Connecting bars 134 are fast with the horizontal post-tensioning bars 126 of each wall assembly 42.

A window frame 136 is mounted in the wall assembly 42 as shown in Figure 21.

Figure 22 shows a detail of a front corner of the garage 60. A vertical end bar 138 is O positioned in an end portion 140 of a wall assembly 42 defining the garage In Figure 23 there is shown a shoring and retaining wall detail of a basement structure, in accordance with the invention. The structure includes a basement slab 142 having an end 0 beam 144. The basement slab 142 is of concrete. Cement of the concrete is a type 'A' normal-class Portland cement. The maximum size of the coarse aggregate in the concrete C- is C Starter bars 154 are positioned in the slab 142 to extend upwardly from the slab 142. The 0 starter bars 154 are connected to reinforcing 156 within the slab 142.

The slab 142 is positioned on a shoring wall 152.

A 3 mm thick sheeting piling assembly 146 that includes panels 148 of corrugated sheet defines a backing for a retaining wall 150 of the basement structure. The retaining wall 150 includes recessed vertical reinforcing bars 158 that are connected to the starter bars 154. The bars 158 are positioned in corrugations 160 of the panels 148 of sheet piling.

A number of H-blocks 162 is positioned on the retaining wall 150. Further vertical reinforcing bars 164 extend from the retaining wall 150 and into the blocks 162. A floor slab 166 is positioned on the H-blocks 162. A reinforcing bar 168 of the floor slab 166 extends into the blocks 162. The reinforcing bars 164 extend into the floor slab 166.

A reinforcing fabric layer 170 is positioned against the bars 164.

A horizontal post-tensioning bar 172 extends across the bars 164 and is capable of being pre-tensioned.

A concrete mix is sprayed onto the corrugated pile sheet piling assembly 146 so that the bars 158, 164 and 172 are embedded in the concrete. When the concrete has set to a predetermined extent, the bar 172 is pre-tensioned to a desired level.

Figure 24 shows a floor plan of the basement structure. The floor plan shows such features as a stairwell 174, pad footings 176, concrete columns 178 and a ramp 180.

Figure 25 shows a detail of an external corner of the basement structure. The external corner includes a pair of adjacent vertical reinforcing bars 182. Connecting bars 184 are connected between the bars 182. The connecting bars 184 are fast with the horizontal bar 172.

Figure 26 shows a detail of an internal corner of the basement structure. The internal corner includes a vertical corner bar 186. Connecting bars 188 extend about the vertical corner bar 186. The connecting bars 188 are fast with the horizontal bar 172.

Applicant believes that the invention provides a structure that can be erected in a simple and cost effective manner. Furthermore, Applicant believes that such a structure is extremely robust considering the speed and cost of manufacture.

Claims (21)

1. A method of constructing a panel assembly for a building structure, the method including the steps of: erecting a support frame on a substrate; mounting structural sheeting on the support frame so that the support frame and Sstructural sheeting together define a zone in which cementitious material is to be set; positioning at least one post-tensioning member in the zone to span the zone; C applying a cementitious, settable material to an inner surface of the structural C sheeting to fill the zone with the settable material, so that the, or each, post tensioning c member extends through the settable material; allowing the cementitious material to set to a predetermined extent; and setting up a predetermined tension in the post-tensioning member once the cementitious material has set to said predetermined extent.

2. A method as claimed in claim 1, in which the step of erecting the support frame on the substrate includes the steps of positioning a pair of spaced support members on the substrate and fastening a bridging member to free ends of the pair of spaced support members.

3. A method as claimed in claim 1 or 2, which includes the step of mounting formwork on the support frame so that the zone is bounded by the structural sheeting, the support frame and the formwork and introducing the cementitious material into the zone to cast the cementitious material in-situ.

4. A method as claimed in claim 3, which includes removing the formwork once the cementitious material has set.

5. A method as claimed in claim 1 or 2, which includes the step of spraying the cementitious material into the zone.

6. A method as claimed in claim 5, which includes the step of removably securing O transverse support members to the structural sheeting to support the structural sheeting while the cementitious material is sprayed on to the structural sheet. S7. A method as claimed in any one of the preceding claims, which includes the step of positioning steel reinforcing in the zone prior to applying the settable cementitious material. S8. A method of constructing a wall assembly, the method including the steps of: o erecting a number of support frames on a substrate; mounting structural sheeting on the support frame so that the structural sheeting oand the support frames define zones in which cementitious material is to be set; positioning at least one post-tensioning member in each zone to span the respective zone; applying a cementitious, settable material to an inner surface of the structural sheeting to fill the zones with the settable material, so that the, or each, post tensioning member extends through the settable material; allowing the cementitious material to set to a predetermined extent; and setting up a predetermined tension in the post-tensioning members once the cementitious material has set to said predetermined extent.

9. A method as claimed in claim 8, which includes the steps of initially applying the cementitious, settable material to alternate zones; allowing the material in said alternate zones to at least partially set; applying the settable material to remaining zones; and using the at least partially set material in the alternate zones as a guide for screeding the material in the remaining zones. A method of constructing a building, such as a dwelling structure, which includes the step of constructing a number of wall assemblies in accordance with the method as claimed in claim 8, in predetermined locations on a base.

11. A method of constructing a retaining wall assembly, the method including the steps of: positioning a layer of sheet piling against soil to be retained; positioning at least one post-tensioning member adjacent the layer of sheet piling; D applying a layer of cementitious material to the sheet piling to cover the, or each, post tensioning member; allowing the cementitious material to at least partially set: and Sapplying a predetermined tension to the, or each, post tensioning member.

12. A method as claimed in claim 11, in which the step of applying the sheet piling A comprises the step of applying corrugated sheet piling.

13. A method as claimed in claim 12, which includes the step of positioning vertical D reinforcing bars in at least a number of the corrugations of the sheet piling before applying the layer of cementitious material.

14. A method as claimed in any one of claims 11 to 13, which includes the step of using formwork to cast the layer of cementitious material in situ on the sheet piling. A method as claimed in any one of claims 11 to 13, which includes the step of spraying the cementitious material on to the sheet piling.

16. A method of constructing a basement structure which includes the step of constructing at least one retaining wall assembly in accordance with the method as claimed in claim 11 on a basement slab.

17. A panel assembly for a building structure, the panel assembly including a support frame that is mountable on a substrate; structural sheeting positioned on the support frame so that the support frame and the structural sheeting define a zone for a cementitious material; a layer of cementitious material positioned against the structural sheeting to fill the zone; and at least one post-tensioning member that extends through the layer of cementitious material with a predetermined tension applied to the member.

18. A panel assembly as claimed in claim 17, in which a pair of vertically spaced post- tensioning members extend through the layer of cementitious material.

19. A panel assembly as claimed in claim 17 or 18, in which the cementitious material is Sin the form of a concrete that contains a polypropylene fibre mesh. A panel assembly as claimed in any one of claims 17 to 19, in which the structural ,A sheeting is of compressed fibre cement (CFC).

21. A wall assembly for a building structure, the wall assembly including at least one Spanel assembly as claimed in any one of claims 17 to S22. A retaining wall assembly that includes Da layer of sheet piling that is positioned against soil to be retained; a layer of cementitious material applied to the layer of sheet piling; and at least one post-tensioning member that extends through the layer of cementitious material and is tensioned to a predetermined extent.

23. A retaining wall assembly as claimed in claim 22, in which the layer of sheet piling comprises corrugated panels of sheet piling.

24. A new method of constructing a panel assembly, substantially as described herein, with reference to the accompanying drawings. A new method of constructing a wall assembly, substantially as described herein, J with reference to the accompanying drawings.

26. A new method of constructing a building structure, substantially as described herein, with reference to the accompanying drawings.

27. A new method of constructing a retaining wall assembly, substantially as described herein, with reference to the accompanying drawings.

28. A new panel assembly, substantially as described herein, with reference to the accompanying drawings.