WO1998050646A1

WO1998050646A1 - Modular sandwich panel and method for housing construction

Info

Publication number: WO1998050646A1
Application number: PCT/AU1998/000330
Authority: WO
Inventors: Nabil Nasri Gazal
Original assignee: Nabil Nasri Gazal
Priority date: 1997-05-08
Filing date: 1998-05-07
Publication date: 1998-11-12
Also published as: CN1103402C; AP1073A; ID29312A; NZ500989A; OA11215A; AP9901691A0; CN1260020A; KR20010012388A

Abstract

A composite panel (1) comprising at least two spaced apart outer laminates (2, 3) and a core laminate (4) sandwiched therebetween. The outer laminates (2, 3) and the core laminate (4) are off-set such that portions (5, 6) of the outer laminates protrude beyond the core by a predetermined margin (A) along a first edge of the panel and such that the core laminate (4) protrudes beyond the outer laminates by a generally corresponding margin (B) along an opposite edge (7) of the panel. The protruding portions of the outer laminates of one panel are adapted nestingly to receive and locate a complementary protruding core portion of an adjacent like panel in interlocking relationship to form a composite panel assembly.

Description

TITLE: MODULAR SANDWICH PANEL AND METHOD FOR HOUSING CONSTRUCTION

FIELD OF THE INVENTION

The present invention relates to composite building panels, and also to a

construction system using such panels.

The invention has been developed primarily for use in the building industry as part

of a modular housing construction system. It will be appreciated, however, that the

invention is not necessarily limited to this particular field of use.

BAC GROUND OF THE INVENTION

In conventional housing construction, walls are fabricated by first erecting a

structural frame which is usually formed from timber. The frame is subsequently clad

internally with a suitable laminate material such as plaster board or gyprock, which is

then finished to conceal joins and finally painted. The external wall is normally formed

either from brick veneer, or a suitable cladding material which is also fastened to the

timber frame. Common external cladding materials include weatherboard, fibre

reinforced cement, and aluminium. Roofing normally consists of corrugated iron or

tiles, again arranged on a timber framework.

This conventional construction technique is particularly labour intensive and

costly, for a number of reasons. For example, many skilled workers from numerous

specialised trades such as builders, brick layers, carpenters, joiners, tilers and plasterers

are required, all of which add considerably to the overall cost. Conventional techniques

also rely heavily on valuable and diminishing material resources, especially timber,

which gives rise to increasing costs as supplies become less available. Moreover,

conventional housing must essentially be built on site, according to architectural plans. There is little scope for pre-fabrication or modular construction, and minimal flexibility

for restructuring a house in a cost effective manner, once built. Furthermore, if a house

is to be demolished, there is little opportunity for recycling or reusing the constituent

materials, which are therefore largely wasted. A further disadvantage with conventional

techniques is that the finished structure offers minimal sound and heat insulation. This

often needs to be addressed later, for example by the addition of insulation batts in the

roof cavity, at additional cost.

Current building techniques also produce structures which are relatively heavy,

particularly where bricks, roof tiles and timber frames are involved. Because of the

weight associated with these materials, the supporting structures must in turn be

relatively large and robust, which adds further weight. The end result is that many light¬

weight materials which may otherwise be suitable, do not possess sufficient strength to

be used in conjunction with conventional housing construction techniques.

In an attempt to ameliorate some of these problems, steel framed houses have been

proposed. It has been found in practice, however, that the resultant cost-benefit is at best

marginal, and most of the fundamental problems remain.

In a further attempt to address these problems, the use of composite panels has also

been proposed. Such panels typically incorporate a series of layers or laminates

fabricated from a variety of materials to achieve desired strength to weight

characteristics, insulation properties, and the like. A major problem with known

fabrication techniques, however, is that there is a practical limit to the maximum size of

individual panels. This in turn has led to various techniques for joining smaller panels to

form composite panel assemblies of the required size. In the past, however, inadequate j -

techniques for joining the panels have resulted in such structures being relatively weak.

The resultant loss of structural integrity has meant that in practice, the potential strength

to weight characteristics offered by composite panels have not been able to be realised in

large scale applications, including housing in particular. For this reason, in the past.

composite panels have typically only been used to form internal partitions and non-load-

bearing walls, where significant structural integrity is not required. As such, the

fundamental problems associated with conventional building methods have remained

unsolved. Hence, there is a long felt need for a more efficient and cost-effective

alternative to existing housing construction techniques.

It is. an object of the present invention to overcome or substantially ameliorate at

least some of these disadvantages of the prior art.

DISCLOSURE OF THE INVENTION

Accordingly, in a first aspect, the invention as presently contemplated provides a

composite panel comprising at least two spaced apart outer laminates and a core laminate

sandwiched therebetween, the outer laminates and the core laminate being off-set such

that portions of the outer laminates protrude beyond the core by a predetermined margin

along a first edge of the panel and such that the core laminate protrudes beyond the outer

laminates by a generally corresponding margin along an opposite edge of the panel,

whereby the protruding portions of the outer laminates of one panel are adapted

nestingly to receive and locate a complementary protruding core portion of an adjacent

like panel in interlocking relationship to form a composite panel assembly.

In the preferred embodiment, a generally U-shaped channel member covers the

protruding portion of the core laminate to form a stud. The channel member is preferably defined by spaced apart flanges and an intermediate web disposed such that

the tlanges lie parallel to and immediately inside the respective outer laminates along the

corresponding edge of the panel and the eb extends between the flanges to cap the

protruding portion of the core laminate. The channel member is preferably disposed

such that the flanges extend marginally between the core laminate and the respective

outer laminates. In this way, the channel member is adapted to be pressed into position

and is generally self-locating.

The channel members are preferably pressed from sheet metal and are oriented in

use to form vertically extending studs between adjacent wall panels, thereby providing

structural ■integrity for the composite wall.

In an alternative configuration, the channel member may be disposed on the

opposite side of the panel with the flanges inserted between the protruding portions of

the outer laminates and the web spaced outwardly, away from the core laminate. In this

configuration, the channel member protrudes beyond the outer laminates to define a

tongue formation similar to the protruding core on the opposite side of the panel, and at

the same time forms a longitudinal cavity or duct bounded by the recessed edge of the

core laminate, the channel flanges, and the channel web. This cavity may be used for

concealed routing of building services such as electrical cables, water pipes,

telecommunication lines, and the like.

In a first preferred form of the invention, the core laminate is formed from

expanded polystyrene foam with one outer laminate being formed from plywood and the

other outer laminate being formed from plasterboard or gyprock. This embodiment of

the invention is particularly suitable for use as an external wall, with the plywood layer facing outwardly to receive a final weatherproof finish in situ. Preferably, in this

configuration, a layer of expanded steel mesh is stapled to the plywood laminate.

Cement render is then applied such that the expanded steel mesh layer acts as reinforcing for the cement. A final protective coat of paint may then be applied. The internal

plasterboard or gyprock layer is preferably finished to conceal join lines and painted, in

the conventional manner.

In a second preferred form of the invention, both the outer layers may be formed

from gyprock or plasterboard. Panels manufactured according to this configuration are

particularly suitable for use as internal walls or partitions, where weatheφroofmg is not

required. ■

In the various embodiments of the invention described above, the outer laminates

are preferably secured to the core laminate by means of a cross-linking polymer

adhesive.

In one preferred embodiment, adjacent panels are secured in overlapping tongue

and groove relationship by at least one fastener, extending through an outer laminate of

one panel, through a flange of the channel member or stud and into the core laminate of

the adjacent panel, thereby securing the adjoining panels and the intermediate stud

together. Preferably, a line of spaced apart screw fasteners extend along the overlapping

edges of each adjacent pair of panels.

In a third preferred form of the invention, the foam core laminate may be

sandwiched between outer layers of sheet metal. This arrangement is particularly well

adapted for use as a roof panel. Preferably, the internal laminate is formed from flat

sheet metal whilst the external laminate is formed from corrugated sheet metal to provide increased strength, improved water run-off, and a conventional corrugated iron

appearance. Ridge capping strips, eaves, trimming strips, guttering and the like may be fitted as required.

According to a second aspect, the invention provides a method of forming a

composite panel, said method comprising the steps of sandwiching a core laminate

between spaced apart outer laminates such that portions of the outer laminates protrude

beyond the core by a predetermined margin along a first edge of the panel and such that

the core laminate protrudes beyond the outer laminates by a generally corresponding

margin along an opposite edge of the panel, whereby the protruding portions of the outer

laminates'of one panel are adapted nestingly to receive and locate a complementary

protruding core portion of an adjacent like panel in interlocking relationship to form a

composite panel assembly.

According to a third aspect, the invention provides a building structure comprising

internal and external walls, each being formed as an interlocking composite panel

assembly substantially as defined above.

Preferably, the building structure further comprises a roof formed as an

interlocking composite panel assembly as previously defined. A generally U-shaped

capping strip is preferably placed along the upper marginal edges of the wall panels to

provide additional structural strength and to facilitate fastening of the roof panels.

According to a fourth aspect, the invention provides a method of building a

housing structure comprising the steps of forming external walls, forming internal walls,

and forming a roof, each from a series of interlocking composite panels substantially as de fined above, and fastening the respective panels together to form a stable housing structure.

Preferably, the housing structure is adapted to be assembled on a concrete slab. In

this case, the lower marginal edge of the external outer laminate of each wall panel

preferably extends downwardly beyond the core laminate and the internal laminate to

define a right angled rebate adapted to rest along a corresponding edge portion of the

concrete foundation slab. Preferably also, fasteners such as "dyna-bolts" are placed to

extend through the external outer laminate and into the side of the foundation slab to

prevent the housing structure from lifting in high wind conditions. In the preferred

embodiment, a weatherproof flashing strip is positioned between the foundation slab and

the overlying wall panels.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example

only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view showing a composite panel, for use as part of an

external wall in a housing structure according to the invention;

Figure 2 is a perspective view showing the external wall panel of Figure 1, with

the outside layer finished with expanded steel mesh reinforcing and cement rendering;

Figure 3 is a cutaway plan view showing a pair of panels according to Figures 1

and 2, interlocked and fastened together in tongue and groove relationship to form a

composite panel assembly according to the invention;

Figure 4 is a perspective view showing the reinforcing channel member or stud of

the panels of Figures 1 and 2; Figure 5 is a perspective view showing a composite panel similar to that shown in

Figure 1. adapted for use as part of an internal wall according to the invention;

Figure 6 is a plan view showing the use of a stud positioned in reverse orientation

to connect adjacent panels in female to female relationship and thereby to define a

concealed duct for service lines;

Figure 7 is a cutaway perspective view showing a composite panel adapted for use

as part of a roofing assembly according to the invention;

Figure 8 is a cutaway perspective view showing a composite panel adapted for use

as a structural beam according to the invention;

Figure 9 shows the use of a saddle bracket adapted to mount the beam of Figure 8

to an abutting wall panel;

Figure 10 shows a double sided saddle bracket adapted to mount structural beams

in coaxial alignment on opposite sides of an intermediate wall panel;

Figure 1 1 is a cross-sectional detail showing a method of mounting the external

wall panels to a concrete foundation slab according to the invention;

Figure 12 is a front elevation showing the mounting detail of Figure 1 1 ;

Figure 13 is a plan view showing a wall to wall corner detail according to the

invention;

Figure 14 is a cross sectional view showing a wall to roof fastening method

according to the invention; and

Figure 15 is a front elevation showing a housing structure fabricated from

composite panels according to the invention. PREFERRED EMBODIMENT OF THE INVENTION

Referring firstly to Figures 1 to 4, the invention provides a composite panel 1

comprising two spaced apart outer laminates 2 and 3, and a core laminate 4 sandwiched

therebetween. The outer laminates and the core laminate are offset such that respective

edge portions 5 and 6 of the outer laminates protrude beyond the core by a

predetermined margin A along a first edge of the panel. Similarly, an edge portion 7 of

margin B along the opposite edge of the panel. This arrangement of laminates defines a

tongue and groove configuration whereby the protruding portions 5 and 6 of the outer

laminates of one panel are adapted nestingly to receive and locate the complementary

protruding core portion 7 of an adjacent like panel in interlocking relationship to form a

composite panel assembly, as shown in Figure 3, and described in more detail below.

In one preferred embodiment, the core laminate 3 is formed from expanded

polystyrene foam, between 20mm and 100mm, and ideally around 50mm to 60mm thick.

In the embodiment shown in Figure 1 , the outer laminate 2 is formed from plywood

around 3mm thick and the other outer laminate 3 is formed from plasterboard or

gyprock, and is around 10mm thick. The outer laminates are bonded to the core with a

special purpose cross-linking polymer adhesive suitable to the purpose. This form of

panel is particularly suitable for use as an external wall, with the plywood layer facing

outwardly to receive a wea heφroof finish.

A preferred form of external finish is shown in Figure 2, whereby a sheet of

expanded steel mesh 10 is stapled to the plywood laminate and subsequently covered

with a layer of cement rendering 1 1. In this way, the steel mesh acts as reinforcement for the rendering. A final protective coat of weatheφroof paint is then applied. The

internal plasterboard or gyprock layer is filled to conceal the join lines, finished and

finally painted in the conventional manner, well known to those skilled in the art.

A generally U-shaped channel member 15 covers the protruding portion of the core

laminate 4. to form a stud. As best seen in Figure 4, the channel member or stud 15 is

defined by spaced apart flanges 16 and an intermediate web 17 with a longitudinally

extending rebate 18 for added strength. Once in position, the flanges 16 lie parallel to

and immediately inside the respective outer laminates 2 and 3 along the corresponding

edge of the panel whilst the web 17 extends between the flanges to cap the protruding

portion 7 of the core laminate. The flanges extend marginally between the core laminate

and the respective outer laminates so that, once pressed into position the stud is generally

self-locating, although adhesive is preferably also used.

The channel members 15 are pressed from sheet metal and oriented in use such

that, in a wall, the studs extend vertically between adjacent panels to provide structural

integrity.

In the preferred form of the invention, the standard sizes for external wall panels

range from approximately 900mm in width, 2500-4000mm in height and 65-90mm in

depth. It will be appreciated, however, that the panels may be fabricated in any desired

size or shape, depending upon the intended application and production capabilities.

Once produced the panels may be cut down as required, for example to accommodate

windows, doors, beams, roof panels, and other fittings, without loss of structural

strength. Figure 5 shows a variation on the panel of Figure 1 , wherein both outer layers 2

and 3 are substantially identical and are formed from gyprock or plasterboard. Panels

manufactured according to this configuration are particularly suitable for use as internal

walls, where weatheφroofing is not required.

Figure 6 shows an alternative form of assembly whereby the protruding edges 5

and 6 of a pair of panels are butted together in female to female relationship and an

additional channel member or stud 15 is positioned in between such that the channel web

is spaced apart from the core laminate of one of the panels. In this reverse configuration,

the channel member protrudes beyond the outer laminates of the left hand panel (when

viewing the drawing) to form a tongue in a manner similar to the protruding core portion

on the opposite side of the panel. In this way, the left side panel engages the right side

panel in tongue and groove relationship. At the same time, the stud forms a longitudinal

cavity or duct 20 bounded by the recessed edge of the core laminate of the left side

panel, the channel flanges, and the channel web. This cavity may be used for concealed

routing of building services such as electrical cables, water pipes, telecommunication

lines, and the like without the need for any separate routing processes or additional

materials, and without weakening the structure as a whole.

As best seen in Figure 3, adjacent panels are fixedly secured in overlapping tongue

and groove relationship by a series of screw fasteners 21. each extending through an

outer laminate of one panel, through the adjacent flange of the channel member or stud,

and into the underlying core laminate of the adjoining panel, thereby firmly securing the

panels together. A line of screw fasteners thus extend along the adjoining edges of each

adjacent pair of panels. The panels are further secured by a top capping strip 22 which also serves to cover and seal the top surfaces of the wall panels and to provide additional

overall structural integrity. The capping strip is best illustrated in Figures 9, 1 1 and 14.

Figure 7 shows a further variation wherein a specially shaped foam core laminate 4

is sandwiched between outer layers 2 and 3 of sheet metal, the upper layer 2 being

corrugated to provide increased strength, improved water run-off and a conventional

aesthetically pleasing appearance. This arrangement is particularly well adapted for use

as a roof panel 24 since, being essentially self-supporting, it obviates the need for a roof

framing structure other than a central support beam as described below.

Figure 8 shows how the basic elements of the panel system may be adapted to

form a high strength and extremely light weight structural beam 25. The beam is thus

formed as an elongate composite panel comprising identical outer laminates 2 and 3

formed from plywood, preferably 3mm in thickness, sandwiching a core laminate 4

formed from expanded polystyrene foam, preferably 50mm in thickness as per the panels

described above. The same cross-linking polymer adhesive is used to adhere the

laminates together. A pair of channel members 15 are respectively disposed along the

top and bottom faces of the beam, to provide additional bending strength. The channels

also act as capping strips to seal and protect the relatively soft foam core laminate. It has

been found that this beam provides adequate strength to support a composite panel

roofing structure as described above, without the requirement for supplementary

framework or trusses, and without adding significantly to the overall weight or cost of

the building.

Figure 9 shows the use of a saddle bracket 26 used to anchor the structural beam

25 of Figure 8 to a vertical wall panel. The saddle bracket is cut and folded from a - 1 J

straight length of 90° angled sheet metal as shown, using a suitable template or jig. It is

then hooked over the upper edge of the wall panel in the appropriate location, and

secured into position with screw fasteners, some of which extend into the top metal

capping strip 22, and some of which extend directly into the panel, ideally into a vertical

stud to give direct metal-metal engagement between these primary structural elements.

This arrangement provides adequate support for the structural beam, without the need to

cut slots, recesses or rebates into the wall panel itself. This substantially expedites the

construction process without compromising structural integrity. A similar double-sided

saddle bracket 27 may be used, if the structural beam is effectively to continue from the

opposite side of the wall panel, as would often be the case with internal walls. This is

best illustrated in Figure 10.

Figure 11 shows how in building and housing construction applications, the wall

panels are fastened to a concrete foundation slab 30. The concrete slab is first poured to

the appropriate dimensions using conventional form work techniques. The lower surface

of each external wall panel is rebated, such that the lower marginal edge 31 of the

external laminate 2 of each panel extends downwardly beyond the core laminate 4 and

the internal laminate 3 by a margin C. The resultant 90° rebate allows the panel to rest

along the outer edge of the foundation slab, with the lower edge 3 1 of the outer laminate

providing positive and accurate lateral positioning. A correspondingly shaped flashing

strip 32 is then laid along the edge of the slab for weather-proofing, as well as to seal and

protect the lower surfaces of the panels. The wall panels are then positioned as shown in

Figure 1 1 such that the flashing strip is tightly sandwiched between the rebates of the

panels and the corresponding edge of the slab. At this stage, the wall panels are secured in position by dyna-bolts 34 or similar fasteners, which extend through the lower edge

3 1 of the outer laminate, and directly into the slab through pre-drilled poles.

Where adjacent wall panels join, a metal anchor strip 35 is used. As best seen in

Figure 12. the lower end 36 of the anchor strip is positioned so as to overlie the outer

vertical face of the foundation slab, whilst the upper end 37 of the strip overlies the wall

panels and more particularly the vertical stud 15. In this way, a lower fastener such as a

dyna-bolt 34 extends through the lower end 36 of the anchor strip, through the lower

edges 31 of the outer laminates, and thence into the slab. The upper fasteners 21 extend

through the upper end 37 of the anchor strip, through the outer laminates of the adjacent

panels, through the underlying stud, and into the core. By this means, the entire panel

assemblies, and not merely the outer laminates, are anchored directly to the foundation

slab. Moreover, the studs are disposed to transfer load directly from the walls and the

roof to the concrete foundation. It has been found that this anchoring method provides a

structure capable of withstanding extreme weather conditions, including cyclonic wind

loadings, which would demolish many structures built in accordance with conventional

techniques.

Figure 13 shows an enlarged corner detail, illustrating how the wall panels 1 are

abutted together at a 90° corner, and joined by means of an angled metal corner strip 40.

Each face of the corner strip is screw fastened where shown into the underlying stud of

the corresponding panel to cover the join line and to provide additional structural

strength.

Figure 14 shows a preferred arrangement for securing an inclined roof panel 24 to

a vertical wall panel 1 , by means of respective internal and external angle brackets 43 and 44. As shown in the drawing, screw fasteners are used to secure the lower face of

each bracket 43 and 44 to the top capping strip and elsewhere on the wall panel whilst

the upper face of the angled bracket is screw fastened to the underside of the roof panel.

The join line is covered and sealed internally by means of cornice whilst an external

cover strip (not shown) may also be provided for thermal insulation and weather

protection.

Turning now to describe briefly the method of constructing a house or other

building in accordance with the present invention, the concrete foundation slab 30 is first

laved using conventional form work techniques. The flashing strip 32 is then positioned

around the periphery of the foundation slab. The external wall panels 1 are then

positioned such that the outer edge of the concrete slab nests in the rebate with the lower

edge 31 of each panel extending downwardly over the outer edge of the slab. The wall

panels are then secured to the slab with dyna-bolts 34 or similar fastening elements, and

anchor strips 35 are secured into position across the joints between adjacent panels. At

this stage, the screw fasteners 21 are installed along the overlapping edges of each

adjacent pair of panels. The corners are then joined using corner strips 40, as shown in

Figure 13. The upper edges of the wall panels are then covered and sealed by the U-

shaped capping strips 40, as shown in Figures 9 and 1 1, which adds further structural

integrity to the panel assembly. Window and door frames are cut from the wall panels as

required, and finished with framing elements formed from timber or aluminium

extrusions, as required. At this stage, the external wall structure is complete, save for

finishing which will be described below. Next, the main roof beam, of the type shown in Figure 8, can be added by means

of saddle brackets 26 and 27 of the type shown in Figures 9 and 10 respectively. Roof

panels 24 of the type shown in Figure 6 are then added, as shown in Figure 14. The roof

structure is finished with a capping strip 50 and guttering 51, as shown in Figure 15.

Internal walls are then formed as required, using interior wall panels of the type

shown in Figure 5. Again, spaces for internal windows and doors are cut from the panels

and framed as required. The internal joints between the plaster board sheets associated

with the discrete panels are concealed and finished using conventional plastering

techniques, and finally painted. Skirting and cornices may also be added as required to

conceal floor- wall and wall-roof joints, for added weather protection, and to provide a

conventional aesthetic appearance.

The exterior panels may be weatheφroofed and finished as desired. A particularly

preferred form of finishing, however, involves the step initially of stapling expanded

steel mesh sheeting 10 to the exterior plywood laminate 2, and subsequently applying a

layer of cement render 1 1 , within which the expanded steel mesh acts as reinforcement.

The render is finally painted, to give the appearance of a conventional cement rendered

brick veneer dwelling.

Advantageously, a house, factory or other building manufactured in accordance

with the present invention can be completed in a small fraction of the time involved

using conventional building techniques, and at an even smaller fraction of the cost.

Because the structure is so light, less elaborate foundations and structural framing are

required, which further reduces material and labour costs. Because the entire set of

panels may be pre- abricated off site, the building can be erected with minimal use of skilled labour, further reducing costs. Because of the laminate construction of the

panels, and in particular the substantial polystyrene foam core, the building inherently

possesses thermal and acoustic insulation properties far superior to those exhibited by

conventional buildings, again without the use additional resources such as fibreglass

batts or the like. Because of the unique way in which the panels are anchored to the

concrete foundation slab, the structure is particularly resistant to wind loadings, even

under cyclonic conditions. A further advantage offered by structures built in accordance

with the present invention is that of flexibility in design. Even after the structure has

been completed, internal as well as external walls may be added, removed or changed as

required, without being constrained by an underlying frame work as is the case in

conventional structures.

Furthermore, an entire house may be disassembled, packed away, transported to

another site and subsequently rebuilt with considerable ease. Even in the event that a

dwelling is to be entirely demolished, the individual panels and other components may

simply be re-used in a new project with virtually no wastage of raw materials.

Many of the above advantages flow from the fact that the panels in accordance

with the present system provide their own inherent structural integrity and thus the

system as a whole avoids the need altogether for a separate frame work. It will thus be

appreciated that the invention provides practical and commercially significant

improvements over the prior art.

Although the invention has been described with reference to specific examples, it

will be appreciated by those skilled in the art that the invention may be embodied in

many other forms.

Claims

I . A composite panel comprising at least two spaced apart outer laminates and a core

laminate sandwiched therebetween, the outer laminates and the core laminate being off┬¼

set such that portions of the outer laminates protrude beyond the core by a predetermined

margin along a first edge of the panel and such that the core laminate protrudes beyond

the outer laminates by a generally corresponding margin along an opposite edge of the

panel, whereby the protruding portions of the outer laminates of one panel are adapted

like panel in interlocking relationship to form a composite panel assembly.

2. A composite panel according to claim 1, further including a generally U-shaped

channel member adapted to cover the protruding portion of the core laminate to form a

stud.

3. A composite panel according to claim 2, wherein said channel member is defined

by spaced apart flanges and an intermediate web disposed such that the flanges lie

parallel to and immediately inside the respective outer laminates along the corresponding

edge of the panel and such that the web extends between the flanges to cap the

protruding portion of the core laminate.

4. A composite panel according to claim 3, wherein the channel member is disposed

outer laminates whereby the channel member is adapted to be pressed into position and

is substantially self-locating.

5. A composite panel according to any one of claims 2 to 4, wherein the channel

members are pressed from sheet metal and are oriented in use to form generally vertically extending studs between adjacent panels, thereby providing additional

structural integrity for the composite panel assembly when used to form a composite

wall.

6. A composite panel according to claim 3, wherein the channel member is disposed

on the opposite side of the panel with the flanges inserted between the protruding

portions of the outer laminates and the web spaced outwardly away from the core

laminate, in a reverse orientation.

7. A composite panel according to claim 6, wherein the channel member in the

reverse orientation protrudes beyond the outer laminates to define a tongue formation

similar to. the protruding core on the opposite side of the panel for engagement with a

like panel, and at the same time forms a longitudinal cavity bounded by the recessed

edge of the core laminate, the channel flanges and the channel web, the cavity being

adapted to facilitate concealed routing of building services.

8. A composite panel according to any one of the preceding claims, wherein the core

laminate is formed from expanded polystyrene foam, wherein one outer laminate is

formed from plywood, and wherein the other outer laminate is formed from plasterboard.

9. A composite panel according to claim 8, wherein the panel is adapted for use as an

external wall, with the plywood layer facing outwardly to receive a weathe╧åroof finish

in situ.

10. A composite panel according to claim 9, further including a layer of expanded steel

mesh applied to the outer plywood laminate, and a layer of cement render applied to the

steel mesh, such that the steel mesh acts as reinforcement for the cement render.

1 1. A composite panel according to claim 10, further including a final protective coat

of paint applied to the cement render to produce a substantially weathe╧åroof finish.

12. A composite panel according to claim 1 1, wherein the internal layer of

plasterboard is filled and finished to conceal join lines.

13. A composite panel according to any one of claims 1 to 7, wherein the core

laminate is formed from expanded polystyrene foam and wherein both outer layers are

formed from plasterboard.

14. A composite panel according to claim 13, being adapted for use as an internal wall

or partition.

15. A composite panel according to any one of the preceding claims, wherein the outer

laminates are secured to the core laminate by means of a cross linking polymer adhesive.

16. A composite panel according to any one of the preceding claims, wherein

adjoining panels of a panel assembly are secured in overlapping tongue and groove

relationship by at least one fastener, said fastener extending through an outer laminate of

one panel, and into the core laminate of the adjacent panel, thereby securing the

adjoining panels together.

17. A composite panel according to claim 16, when dependent upon any one of claims

3 to 16. wherein said fastener extends through an outer laminate of one panel, through a

flange of the channel member and into the core laminate of the adjacent panel, thereby

securing the adjoining panels and the intermediate stud together.

18. A composite panel according to claim 16 or claim 17, wherein a linear array of

spaced apart screw fasteners extend along the overlapping edges of each adjacent pair of

panels.

19. A composite panel according to any one of the preceding claims, wherein the core

laminate is between 20mm and around 100mm in thickness.

20. A composite panel according to claim 19, wherein the core laminate is formed

from expanded polystyrene foam and is between 50mm and around 60mm in thickness.

21. A composite panel according to any one of the preceding claims, wherein the panel

is approximately 600mm to 1200mm in width. 2500mm to 4000mm in height and 65mm

to 90mm in depth.

22. A composite panel according to claim 1, comprising a foam core laminate

sandwiched between outer layers of sheet metal.

23. A composite panel according to claim 22, being adapted for use as a roof panel.

24. A composite panel according to claim 23, wherein the internal outer laminate is

formed from substantially flat sheet metal and wherein the external outer laminate is

formed from corrugated sheet metal to provide increased strength, improved water run

off, and a conventional corrugated iron appearance.

25. A composite panel according to claim 23 or claim 24, wherein an assembly of

interlocking roof panels is fitted with ridge capping strips, eaves and guttering as

required.

26. A building structure comprising internal and external walls, each being formed as

an interlocking composite panel assembly substantially as defined in any one of claims 1

to 25.

27. A building structure according to claim 26, further including a roof formed as an

interlocking composite panel assembly substantially as described in any one of claims 1 to 25, the roof being supported by a structural beam formed as an elongate composite

panel.

28. A building structure according to claim 27, wherein the structural beam is formed

from a core laminate formed from expanded polystyrene foam, outer laminates formed

from plywood, and capping strips formed from generally U-shaped channel members to

cover the exposed longitudinal edge portions of the core laminate.

29. A building structure according to claim 28, wherein the structural beam is

anchored to a vertical wall panel by means of a saddle bracket, the saddle bracket being

cut and folded from an initially straight strip of angled sheet metal, thereby obviating the

need for slots, recesses or rebates in the wall panel.

30. A building structure according to any one of claims 26 to 29, wherein generally U-

shaped capping strips are positioned along the upper marginal edges of the wall panels to

provide additional structural strength for the walls and to facilitate fastening of the roof

panels thereto.

31. A building structure according to any one of claims 26 to 30, wherein the structure

is adapted for assembly on a concrete foundation slab.

32. A building structure according to claim 31, wherein the lower marginal edge of the

external outer laminate of each wall panel extends downwardly beyond the core laminate

and the internal laminate to define a substantially right angled rebate adapted to rest

along a corresponding edge portion of the concrete foundation slab.

33. A building structure according to claim 32, further including fastening elements

extending through the external outer laminate and into the foundation slab to prevent the

structure from lifting in adverse weather conditions.

34. A building structure according to claim 33, wherein the wall panels are fastened to

the foundation slab by means of "dyna-bolts".

35. A building structure according to any one of the claims 31 to 34, further including

a weathe╧åroof flashing strip positioned between the foundation slab and the overlying

wall panels.

36. A method of forming a composite panel, said method comprising the steps of

sandwiching a core laminate between spaced apart outer laminates such that portions of

the outer laminates protrude beyond the core by a predetermined margin along a first

edge of the panel and such that the core laminate protrudes beyond the outer laminates

by a generally corresponding margin along an opposite edge of the panel, whereby the

protruding portions of the outer laminates of one panel are adapted nestingly to receive

and locate a complementary protruding core portion of an adjacent like panel in

interlocking relationship to form a composite panel assembly.

37. A method of forming a building structure, comprising the steps of forming external

walls, forming internal walls, and forming a roof, each from a series of interlocking

composite panels, each panel being formed substantially in accordance with the method

of claim 36, and comprising the further step of fastening the respective panels together to

form a stable housing structure.

38. A method according to claim 37, comprising the further step of assembling the

housing structure on a concrete foundation slab.

39. A method according to claim 38, comprising the further step of forming the lower

marginal edge of the external outer laminate of each wall panel so as to extend

downwardly beyond the core laminate and the internal laminate, and thereby defining a substantially right angled rebate adapted to rest along a corresponding edge portion of

the concrete foundation slab.

40. A method according to claim 39, comprising the further step of installing fastening

elements so as to extend through the outer laminate and into a side of the foundation

slab, thereby to prevent the housing structure from lifting in adverse weather conditions.

41. A method according to claim 40, wherein said fastening elements are "dyna-bolts'\

42. A method according to claim 41 , including the further step of positioning a

weathe╧åroof flashing strip between the foundation slab and the overlying wall panels.