AU2009244980A1

AU2009244980A1 - Wall system

Info

Publication number: AU2009244980A1
Application number: AU2009244980A
Authority: AU
Inventors: Johannes La Grouw; Jeffrey Robert Parker; Kerry Ronald Treloar
Original assignee: LOCKWOOD BUILDINGS Ltd
Current assignee: LOCKWOOD BUILDINGS Ltd
Priority date: 2008-05-07
Filing date: 2009-05-06
Publication date: 2009-11-12
Anticipated expiration: 2029-05-06
Also published as: US20110094173A1; WO2009136800A1; AU2009244980B2

Description

WO 2009/136800 PCT/NZ2009/000069 WALL SYSTEM FIELD OF THE INVENTION The present invention relates to a wall system which has a solid wood construction on 5 both an inner and outer side with an insulation cavity between, and to an improved building construction utilising the wall system. BACKGROUND TO THE INVENTION A significant sector of the residential building construction market has been based 10 around buildings having a solid timber construction. In the past buildings of this type included wall sections made from timbers stacked on edge. Each timber had a complementary tongue and groove arrangement interlocking with the adjacent timber above and a further complementary tongue and groove arrangement interlocking with the adjacent timber below. This provided an attractive exterior and interior appearance. The construction also provides a strong low 15 maintenance structure. However a solid wood exterior wall has insulation properties limited by the thermal conductivity of the timber. Solid timber walls would not meet the exterior wall insulation requirements for modern New Zealand building standards without being exceptionally thick. Exceptionally thick solid walls are not economically practical, and if the components are 20 manufactured in kitset form the components would be so heavy as to be impractical to assemble. The present applicant has previously proposed improved systems in which each building member in the stack is made up of a pair of boards held apart by spacers to have an insulation space between the pair of boards. In New Zealand patent 185995 the pairs of boards are spaced by a series of plastic webs running at an oblique angle relative to the line of the boards. In New 25 Zealand patent 329387/330205 the pairs of boards are spaced by a pair of wooden webs running parallel with and the length of the boards. Individual complete building members are stacked to form the wall structure. SUMMARY OF THE INVENTION 30 It is an object of the present invention to provide a wall system that improves on the wall structures of the aforementioned prior art, or which will at least provide the building industry with a useful choice. Accordingly in a first aspect the present invention consists in a wall comprising: 1 WO 2009/136800 PCT/NZ2009/000069 a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the height, said boards arranged in an interior stack of boards and an exterior stack of boards, the 5 interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, and vertical members rigidly spacing each said stack of boards at spaced locations along said wall, each said vertical member having a spanning portion between the interior and exterior stacks of boards, a retainer, associated with a first vertical edge, engaged in a vertical slot, having 10 a complementary horizontal cross-section to said retainer, in said inner face of one stack of boards, and a retainer, associated with its other vertical edge, engaged in a slot, having a complementary horizontal cross-section to said retainer; formed in the inner face of the other stack of boards, such that said interior and exterior stacks of boards are spaced apart by the width of said spanning portion, which extends across the height of a plurality of boards of each said 15 stack of boards. Preferably said spanning portion at least is formed of a material having a thermal conductivity similar to or less than a plastic material such as polypropylene. 20 Preferably said spanning portion is formed from a plastic material such as polypropylene. Preferably said vertical member may be formed as a unitary element including said retainers together with said spanning portion. 25 Alternatively said vertical member comprises a plurality of said retainers, in use the retainers being connected with the vertical edges of said spanning portion and engaged in said slots of said interior and said exterior stack of boards. 30 Preferably the retainers are formed from the same material as said spanning portion. Alternatively the retainers are formed from aluminium extrusions. Preferably said retainers are a fraction of the length of the vertical member, there being 35 a plurality of retainer engaged along each respective edge of said spanning portion. 2 WO 2009/136800 PCT/NZ2009/000069 Preferably said vertical member includes stiffening flanges or ribs at intervals along the height of said spanning portion, said flanges extending laterally from said spanning portion and laterally across the width of said spanning portion. 5 Preferably the flanges or ribs may be integrally formed with the spanning portion. Preferably said spanning portion of said vertical member includes one or more cut-out regions. 10 Preferably said slot of each said stack of boards comprises a dovetail mortise having a tapered neck substantially at the inner surface of the stack of boards and a broader portion extending into the stack of boards to a depth part way through the thickness of the stack of boards. 15 Preferably the dovetail mortise is formed by a pair of intersecting cuts, each cut extending beyond the intersection to create the dovetail, with the intersection of the cuts creating the tapered neck of the slot. 20 Preferably the retainers of said vertical member comprise narrow flanges extending into divergent parts of said dovetail mortise from a common base portion residing in said intersection of said cuts. Preferably said gap between said interior and exterior stacks of boards is at least 80mm. 25 Preferably the gap is greater than 100mm, but less than 300mm. Preferably the wall includes a plurality of said vertical members at regularly spaced intervals along the wall. 30 Preferably said wall includes insulation material having a high thermal resistance (low thermal conductivity) substantially completely occupying the space between said interior and exterior stacks of boards in the regions between adjacent vertical members. 3 WO 2009/136800 PCT/NZ2009/000069 Preferably the wall further comprises at least one brace assembly, the brace assembly comprising: a first bracket for fixing the brace assembly to a base supporting the wall or to a'bottom portion of the wall, 5 a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and 10 second brackets to a predetermined tension level, the tie rod being located between the two spaced apart stacks of boards. Preferably the tie rod extends at an angle of approximately 50 degrees to 90 degrees relative to the length of the boards. 15 Preferably the tie rod extends at an angle of approximately 55 degrees to 75 degrees relative to the length of the boards. Preferably the wall includes two said brace assemblies, the two brace assemblies acting 20 from opposite directions such that horizontal shear forces in the stacks of boards created by one brace assembly are substantially balanced by the horizontal shear forces in the stacks of boards created by the other brace assembly. Preferably the first end and the second end of the tie rod are threaded, the tie rod 25 passing through slots in the first and second brackets, a first nut is threaded onto the first end to couple the first end directly or indirectly to the first bracket, and a second nut is threaded onto the second end to couple the second end directly or indirectly to the second bracket, the first nut and corresponding thread, or the second nut and corresponding thread, or both, acting as the tensioning mechanism for tensioning the tie rod between the first and second brackets to a 30- predetermined tension level by relative rotation between the first nut and the tie rod and second nut, or by relative rotation between the second nut and the tie rod and first nut. Preferably the first end has a fixed head for interfacing with a spanner and the second end is threaded, the tie rod passing through slots in the first and second brackets, the head 35 coupling the first end directly or indirectly to the first bracket, and a nut being threaded onto the 4 WO 2009/136800 PCT/NZ2009/000069 second end to couple the second end directly or indirectly to the second bracket, the nut and the corresponding thread acting as the tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level, the tensioning mechanism being actuated by relative rotation between the nut and the tie rod. 5 Preferably the first bracket or the second bracket, or both, comprises a central curved portion and two flange portions, the central curved portion bridging between the two flange portions, the two flange portions being aligned on a plane, each flange portion having at least one through hole for fixing the bracket via the two flange portions to a corresponding surface or 10 surfaces, with a slot in the central curved portion for receiving the tie rod. Preferably the flange portions extend parallel to a diameter of the curvature of the curved portion, the flange portions being spaced a distance from the diameter towards the central curved portion. 15 Preferably the slot is circumferential and extends through an arc of at least 40 degrees. Preferably the slot is located to a first side of the central curved potion only, and a second side of the central curved portion is without a slot. 20 Preferably the bracket includes a gusset, the gusset extending across a portion of the central curved portion, the gusset being arranged substantially normal to an axis of the curvature of the central curved portion. 25 Preferably the wall includes at least one supporting member fixed to a top surface of the interior stack of boards and the exterior stack of boards, the supporting member bridging across the space between the interior stack of boards and the exterior stack of boards, and the second bracket is fixed to the supporting member. 30 Preferably the flange portions of the second -bracket are wider than the central curved portion, the flange portions extending to a width bridging the interior and exterior stacks of boards, the bracket being fixed via the flange portions to a top surface of the interior stack of boards and the exterior stack of boards. 35 Preferably the first and second brackets have the same dimensions. 5 WO 2009/136800 PCT/NZ2009/000069 Preferably the first bracket is oriented with the curved portion upwards, and the second bracket is oriented with the curved portion downwards. 5 Preferably the brace assembly includes a resilient element for maintaining tension in the tie rod. Preferably a bottom board at the base of a wall stack has an access hole, the access hole passing through the thickness of the board to provide access to the first end of the tie rod. 10 In a second aspect the present invention consists in a building construction constructed from at least two walls as set out above, the at least two walls intersecting, an interior stack of boards of a first wall being joined to an interior stack of boards of a second wall, and an exterior stack of boards of the first wall being joined to an exterior stack of boards of the second wall, 15 such that an insulation space of the first wall communicates with an insulation space of the second wall to create a corner insulation space extending around the corner between the first and second walls and substantially the height of the first and second walls. Preferably the building construction includes insulation in the corner insulation space, 20 the insulation extending continuously between the first and second walls. Preferably an end edge of the interior stack of boards of the first wall has a vertical groove extending the height of the wall, and a side of the interior stack of boards of the second wall has a corresponding vertical groove near an end of the second wall extending the height of 25 the second wall, the first and second walls arranged to butt the end edge of the interior stack of boards of the first wall against the side of the interior stack of boards of the second wall, aligning the vertical grooves of the interior stacks of boards of the first and second walls, and a locking member having a retainer associated with a first vertical edge, engaged in one of said vertical grooves, having a complementary horizontal cross-section to said retainer, and a 30 retainer associated with its other vertical edge, engaged in the other said vertical groove, having a complementary horizontal cross-section to said retainer, such that said locking member locks the interior stacks of boards of the first and second walls together. 6 WO 2009/136800 PCT/NZ2009/000069 Preferably the building construction includes a corner member having a first side and a second side, the first and second sides being at right angles to one another, the corner member extending the height of the walls, and wherein an end edge of the exterior stack of boards of the first wall has a vertical groove 5 extending the height of the first wall and an end edge of the exterior stack of boards of the second wall has a vertical groove extending the height of the second wall, and the corner member has a vertical channel in the first side extending the height of the first wall and a vertical channel in the second side extending the height of the second wall, and an end edge of the exterior stack of boards of the first wall butts against the first side of 10 the corner member, aligning the vertical groove with the vertical channel in the first side, and an end edge of the exterior stack of boards of the second wall butts against the second side of the corner member, aligning the vertical groove with the vertical channel in the second side, and wherein the building construction further includes two connecting members, each connecting member having a retainer associated with a first vertical edge, said retainer engaged in 15 one of said vertical grooves, said vertical grooves having a complementary horizontal cross section to said retainer, and said connecting member having a lug associated with its other vertical edge, said lug engaged in a corresponding one of said vertical channels, said vertical channels having a complementary horizontal cross-section to said lug, such that said connecting members lock the exterior stacks of boards of the first and second walls to the corner member. 20 In a third aspect the present invention consists in a building construction constructed from at least one wall as set out above, the at least one wall being assembled on a base platform, the base platform being supported by a building support structure, wherein a vertical boundary of the building support structure extends beyond a vertical boundary of the base platform, 25 the interior stack of wall boards being stacked at the base platform vertical boundary, and the exterior stack of wall boards being stacked at the building support structure vertical boundary, the space between the interior stack of boards and the exterior stack of boards spanning a gap between the base platform vertical boundary and the building support structure 30 vertical boundary, the space communicating with the gap to create an insulation space extending from between the two stacks of boards downwards between the base platform vertical boundary and the building support structure vertical boundary to below a floor level of the base platform. 7 WO 2009/136800 PCT/NZ2009/000069 Preferably the building construction includes insulation in the insulation space, the insulation extending continuously from between the interior and exterior stacks of boards to below the floor level of the- base platform. 5 Preferably the insulation extends continuously from between the interior and exterior stacks of boards to underneath at least a portion of the floor level of the base platform. Preferably the base platform includes a floor surface, joists and noggings, and the insulation extends under the floor surface and noggings and between the joists. 10 Preferably the building support structure comprises boundary joists and bearers, the base platform being supported by the bearers, the boundary joists having an upper surface in plane with a floor surface of the base platform. 15 Preferably the first bracket is fixed to a nog, the nog being securely fixed to a said boundary joist. In a fourth aspect the present invention consists in a building construction constructed from at least one wall as set out above wherein the interior stack of boards is assembled on a base 20 platform, the interior stack of boards extending to a height above a first roof level, and the exterior stack of boards includes at least one board having at least a portion above the first roof level, the portion being supported by at least one bracket fixed to the interior stack of boards at a position above the first roof level. 25 Preferably the bracket comprises: a first flange and a second flange, the first and second flanges being parallel and spaced apart, in use the first and second flanges being substantially vertical, a central member, the first and second flanges extending from opposite sides of the central member, 30 the first and second flanges each having at least one hole, the first flange being fixed to the inner face of one said stack of boards by fasteners through said at least one hole and the second flange being fixed to the inner face of the other said stack of boards by fasteners through said at least one hole. 8 WO 2009/136800 PCT/NZ2009/000069 Preferably a first web is located within the interior angle formed between the first flange and the central member, the first web extending at least partway across the central member and at least part way across the first flange 5 Preferably a second web is located within the interior angle formed between the second flange and the central member, the second web extending at least partway across the central member and at least part way across the second flange. Preferably the interior angles are 90 degrees. 10 Preferably the holes are sized to allow fasteners to be applied to the inner face of the interior stack of boards at an angle so that the fasteners and necessary fastener tooling clear the upper edge of the bottom board when fixing the bracket to the inner face of the interior stack of boards. 15 Preferably the portion of the board above the first roof level is supported by at least two said brackets, the at least two brackets being spaced by a spacing of approximately 1m. Preferably the central member has through holes and the building construction further 20 comprises: at least one base member fixed to the at least two brackets, the at least one base member being supported by and fixed to the central members via the through holes, at least one brace assembly, the brace assembly comprising: a first bracket for fixing the brace assembly to said at least one base member, 25 a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and* 30 second brackets to a predetermined tension level, the bracing assembly being installed within the spacing between the two spaced apart stacks of boards. In a fifth aspect the present invention consists in a brace assembly for bracing a wall, the 35 brace assembly comprising: 9 WO 2009/136800 PCT/NZ2009/000069 a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom portion of the wall, a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod being 5 coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level. 10 In a sixth aspect the present invention consists in a bracket for a brace assembly comprising: a central curved portion and two flange portions, the central curved portion bridging between the two flange portions, the two flange portions being aligned on a plane, each flange portion having at least one through hole for fixing the bracket via the two flange portions to a 15 corresponding surface or surfaces, and a slot in the central curved portion. In a seventh aspect the present invention consists in a wall supporting bracket comprising: a first flange and a second flange, the first and second flanges being parallel and spaced 20 apart, in use the first and second flanges being substantially vertical, a central member, the first and second flanges extending from opposite sides of the central member, the first and second flanges each having at least one hole. 25 In an eighth aspect the present invention consists in a wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the height, said boards arranged in an interior stack of boards and an exterior stack of boards, the 30 interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, and at least one brace assembly comprising:., a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom portion of the wall, 35 a second bracket for fixing the brace assembly to a top portion of the wall, 10 WO 2009/136800 PCT/NZ2009/000069 a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and 5 second brackets to a predetermined tension level, the tie rod being located between the two spaced apart stacks of boards. In a ninth aspect the present invention consists in a wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the 10 longest dimension, the height being less than the length, and the thickness being less than the height, said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, and 15 two brace assemblies, each brace assembly comprising: a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom portion of the wall, a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod 20 being. coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level, the tie rod being located between the two spaced apart stacks of boards and 25 extending at an angle of 50 degrees to 75 degrees relative to the length of the boards, the two brace assemblies acting from opposite directions such that horizontal shear forces in the stacks of boards created by one brace assembly are substantially balanced by the horizontal shear forces in the stacks of boards created by the other brace assembly. 30 In a tenth aspect the present invention consists in a building construction constructed from at least two walls, each wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 35 height, 11 WO 2009/136800 PCT/NZ2009/000069 said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, the at least two walls intersecting, an interior stack of boards of a first wall being joined 5 to an interior stack of boards of a second wall, and an exterior stack of boards of the first wall being joined to an exterior stack of boards of the second wall, such that an insulation space of the first wall communicates with an insulation space of the second wall to create a corner insulation space extending around the corner between the first and second walls and the height of the first and second walls. 10 In an eleventh aspect the present invention consists in a building construction constructed from at least one wall, the at least one wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 15 height, said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, the at least one wall being assembled on a base platform, the base platform being 20 supported by a building support structure, wherein a vertical boundary of the building support structure extends beyond a vertical boundary of the base platform, the interior stack of wall boards being stacked at the base platform vertical boundary, and the exterior stack of wall boards being stacked at the building support structure vertical ' 25 boundary, the space between the interior stack of boards and the exterior stack of boards spanning a gap between the base platform vertical boundary and the building support structure vertical boundary, the space communicating with the gap to create an insulation space extending from between the two stacks of boards downwards between the base platform vertical boundary and the building support structure vertical boundary to below a floor level of the base platform. 30 In a twelfth aspect the present invention consists in a building construction constructed ,from at least one wall, the at least one wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 35 height, 12 WO 2009/136800 PCT/NZ2009/000069 said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, the interior stack of boards being assembled on a base platform, the interior stack of 5 boards extending to a height above a first roof level, the exterior stack of boards including at least one board having at least a portion above the first roof level, the portion being supported by at least one bracket fixed to the interior stack of boards at a position above the first roof level. 10 In a thirteenth aspect the present invention consists in a method of building a wall comprising the steps of: placing a first wall member on edge on a base platform, erecting a vertical spacing member to be retained in a vertical orientation with a retainer portion associated with each vertical edge of said vertical spacing member engaging within a 15 vertical slot on a face of said first wall member, sequentially placing additional wall members to create two stacks, one either side of said vertical member with each wall member secured to the respective edge of said vertical member in like manner, with said retainer portions of said vertical spacing member retained in aligned slots of said wall members. 20 Preferably the method includes erecting multiple said vertical members at spaced locations along the first said wall member before erecting said stacks of further wall members. Preferably said method includes initially arranging at least one wall member.on either 25 side of a gap sized to take said vertical spacing member, with slots of said wall members aligned across said gap. Preferably said method includes alternately connecting retainer portions much shorter in length than the length of said vertical member to an edge of said vertical member and assembling 30 additional wall members into said stack adjacent said edge. In a fourteenth aspect the present invention consists in a kitset for constructing a wall, said kitset comprising: a first set of boards, each having slots extending across a side face at equivalent locations 35 along said board, and 13 WO 2009/136800 PCT/NZ2009/000069 a second set of boards, each having slots extending across a side face at equivalent locations along said board, and a spacer, whether unitary or an assembly, being longer than a combined width of a plurality of said boards, said spacer having retaining portions along either edge adapted for 5 engaging in said slots of said boards. In a fifteenth aspect the present invention consists in a wall board, the wall board being longer than its width, and wider than its thickness, and having a series of slots across one side face, the side face defined by the width and length of the wall member, the slots aligned 10 perpendicular to the length dimension of the wall board and each having a depth of part of the thickness of the wall board, the slots of said series being separated by at least 400mm. Preferably said slots have a narrow entrance portion and a broader internal portion. 15 Preferably the broader internal portion may be singular or bifurcated. The term "comprising" as used in this specification means "consisting at least in part of'. When interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as 20 "comprise" and "comprises" are to be interpreted in the same manner. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The 25 disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limitmg BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional plan elevation of a wall according to one aspect of the 30 present invention. Figure 2 is a side elevation in cross-section of the wall of Figure 1 with two optional cut-out patterns illustrated in broken lines. Figure 3A is a cross-section of a portion of the vertical spacing element according to one variation of the invention. 14 WO 2009/136800 PCT/NZ2009/000069 Figure 3B is a cross-section of a portion of the vertical spacing element according to another variation of the invention. Figures 4A to 4D illustrate a sequence of constructing a wall according to another aspect of the present invention. 5 Figure 5 is a perspective view with partial cutaway of a wall member according to another aspect of the present invention. Figure 6 is a perspective view of a suitable spacing member. Figure 7A(i) is an end elevation of a wall. Figure 7A(ii) is a side elevation in cross-section of the wall of Figure 7A(i). 10 Figures 7B and 7C are side elevations in cross section of different length walls. Figure 8A is a perspective view of a bracket for a tie rod for bracing the wall of Figure 7. Figure 8B is a cross section of the bracket of Figure 8A. Figure 8C is a cross section of a preferred embodiment of the bracket for a tie rod for 15 bracing the wall of Figure 7. Figure 9A is a sectional view of one embodiment of a tie rod assembly for bracing the wall of Figure 7. Figure 9B is a sectional view of a preferred embodiment of a tie rod assembly for bracing the wall of Figure 7. 20 Figure 10 is a part sectional view of an alternative embodiment of the tie rod assembly incorporating a spring. Figures 11A and 11B are plan views of two arrangements for corners in an improved building construction utilising the wall system. Figures 12A and 12B are cross sectional views of an improved building construction 25 utilising the wall system. Figures 13A and 13B are sectional views of the wall system as part of a building construction above a split level roof. Figure 14A is a side view of a bracket for use in the wall system as part of a building construction above a split level roof. 30 Figure 14B is a view of the bracket in Figure 14A viewed in the direction of arrow B. Figure 15 is a plan view of an internal corner section. DETAILED DESCRIPTION The various inventions herein relate to a wall system that provides an exterior wall for a 35 building having a solid wood interior wall portion, a solid wood exterior wall portion and a 15 WO 2009/136800 PCT/NZ2009/000069 substantial insulation space therebetween. The solid wood interior portion and the solid wood exterior portion are each formed from a stack of wooden boards arranged on edge. The wooden boards may have complementary tongue and groove formations for facilitating stacking, inter engagement and overlapping between adjacent boards. 5 Each board has a length, a height and a thickness. The length is typically the longest dimension, the height being less than the length, and the thickness being less than the height. A board in each stack of boards is typically many times longer than it's height, however, a wall may include a board or boards that have a length that is not significantly longer than the board height. A wall of the present invention may include a board or boards that have a length longer than the 10 width. A wall of the present invention may include a board or boards that have a length dimension similar to the board width. A wall of the present invention may include a board or boards that have a length dimension shorter than the board width. Prior to assembly into a wall, boards of one stack are not connected with boards of the other stack. 15 The boards of each stack are preferably preformed, for example at an offsite location. By preformed we mean boards are cut to length, have any end treatment, edge treatment, surface profiling, vertical boring and so on preformed on them in a manner known in the art. For example the board ends may be formed with mitre cuts for engaging with corner connectors and the edges may be formed with tongue and groove arrangements. The side faces may be profiled 20 to have longitudinal grooves, rounded edges, or other aesthetic qualities as desired. Holes may be drilled perpendicular to the longitudinal dimension from edge to edge to accommodate vertical tie rods in the finished construction. All of these aspects are treatments typically applied to boards in the prior art construction methods which facilitate easy assembly of the boards at a construction site. 25 Referring to Figure 1, after assembly of the wall, or after assembling sections of the wall, suitable insulation 10 may be placed in the cavity formed between the inner and outer wall sections. Suitable insulation may include panel insulation such as expanded plastic foams, fibre insulations such as mineral wool or natural wool pillows, or loose fill mineral wool. According to the present invention the wall design will include two separate wall stacks 30 12, 14 separated by a substantial insulation gap. Referring to Figures 1 and 5 each pre-prepared wall board includes a plurality of slots 16 extending across one -side face. The slots are arranged at regular intervals along the side face. Each slot runs in a direction perpendicular to the length of the board. Each slot extends into the board to a depth part way through the thickness of the board. 16 WO 2009/136800 PCT/NZ2009/000069 The spacing of the slots is preferably selected to accord with readily available insulation units. For example if the desired insulation unit is a substantially rigid foam panel 500mm wide the slots are preferably just greater than 500mm spacing, sufficiently greater to accommodate the width of the spacing members that will occupy a small space between each insulation panel. 5 Each slot preferably has a broader inner portion 17 and a narrower outer portion 18. The slot may be any suitable shape to provide for engagement of a bulbous lug or flange, secured in said broader portion 17 by overhanging lips 19 defined by said narrower portion 18. Each said slot extends from edge to edge of said board, such that said slots can be entered and departed by said bulbous flange from either end. 10 The two stacks of wall boards are held rigidly apart by a set of vertical spacing members 20 engaging with the transverse slots 16 on the faces of the wall boards. In each wall 12, 14 the wall boards are aligned such that the transverse slots 16 of the wall boards of each stack line up one above the other. The wall boards are also preferably aligned such that the slots of the wall boards of one stack are directly opposed across the gap from the slots of the wall boards of the 15 other stack. Each vertical spacer 20 is engaged with the set of wall board slots of one stack along one edge and the opposed set of wall board slots of the other stack along its other edge. Referring additionally to Figures 3A and 3B, the vertical spacer includes a retaining portion 22 associated with each edge that engages in the slots of the wall boards. The retaining 20 portion may be formed integrally with a spanning portion 24 of the vertical member as shown in Figure 3A, or may be formed in sections shorter than the vertical member, for engagement with the vertical member in sections as the wall is assembled as shown in Figure 3B. For example the short sections of retaining member may clip to edges of a spanning portion of the vertical member. The clip engagement may be sliding or press fit type of 25 engagement. The retaining portions 22 include a bulbous flange or flare, or pair of diverging flanges, or similar form having a broader outer portion and a narrower neck portion. The broader outer portion has a sliding fit within the slots of the wall boards. The spanning portion 24 of each vertical spacing member may include a web 26, 30 continuous or discontinuous (for example interrupted by cut-outs 27 or 28), or a series of struts. The web and/or struts may include lateral flanges or ribs to stiffen the spanning portion against buckling under a compressive load from the wall stacks. The spanning portion of the vertical member preferably has a thermal conductivity substantially equivalent to or less than the thermal conductivity of solid polypropylene. The 35 vertical member may be formed from a suitable plastic material such as polypropylene. The 17 WO 2009/136800 PCT/NZ2009/000069 plastic material may be loaded with a filler material, a filler material may also reduce density and/or thermal conductivity or both. The vertical member may be of a continuous cross-section, suitable for extrusion, or may be formed by injection moulding. 5 The vertical members may extend the full height of a complete wall or may extend a partial height of the wall, for example over at least a plurality of boards. The vertical member may include a butt flange 30 adjacent each retaining portion to more firmly restrain the wall boards relative to the spanning portion 24. Referring to Figures 4A to 4D a typical wall is constructed on a base platform 40 10 following a sequence commencing with placing at least one wall board 42 in its intended location on the base platform. The base platform could be a concrete slab. Alternatively the base platform could be a timber structure including joists and nogs, or any other suitable platform being incorporated into a building structure. At least one, and preferably at least two, substantially vertical spacing members 44 are engaged with the wall board or wall boards initially 15 placed on the base platform. The wall board 42 or boards thereby support the vertical members 44 in the upright orientation and the remaining wall boards 46 can be assembled to the structure by sequential addition to the top of the respective wall stack on one or other side of the vertical members. Where the vertical spacing member includes separate retaining portions of shorter 20 length, these retaining portions may be connected with the spanning portion of the vertical member at intervals between adding further wall boards. So in relation to the initial wall boards 42 assembled onto the support platform the retaining portions of the vertical spacing member are slid into the respective slots of the wall boards. In respect of later wall boards 46 the wall boards are slid onto the retaining members 25 from above, until the two stacks of boards 47, 48 are completed, as shown in Figure 7A(i). It is well known in the building industry to brace a wall of a building by provide bracing at an angle to the vertical. In a traditional wooden framed wall having timber studs and nogs, bracing in the form of a metal strip is typically applied to the constructed timber wall frame at an angle to the studs, prior to the constructed frame being erected on the-base platform. The 30 bracing strip is typically nailed or tacked to the frame wall at positions where the bracing contacts the face of the studs and nogs. According to one invention herein, bracing may be applied to the wall system, within the internal cavity between the two stacks of boards. Referring to Figure 7A(ii), the wall system may include bracing comprising tie rods 51 and tie rod brackets 50. 18 WO 2009/136800 PCT/NZ2009/000069 Prior to placing both boards 42 on the base platform, at least one bracket 50 is fixed to the base platform 40 in an appropriate position as shown. Bracket 50 is preferably positioned approximately centrally between the two stacks of boards 47, 48. A corresponding bracket 50 is provided at the top of the two stacks of boards. Preferably the bracket 50 at the top of the wall 5 is located near an end 45 of the stacks of boards. The bracket at the top of the wall 49 is preferably fixed to a supporting member 52 that bridges over the two stacks of boards 47, 48. The supporting member 52 may extend for a portion of the length of the wall as shown in Figure 7A(ii). Alternatively, the supporting member 52 may extend substantially the length of the wall 49. A slot 58 is provided through the 10 supporting member 52 to allow the tie rod 51 to pass from below through to the bracket 50. Alternatively two supporting members may be provided, spaced apart to allow tie rod access to the bracket 50. The supporting member or members may be a piece or pieces of timber. Natural timber supporting members are prepared with the majority of the longitudinal wood grain 15 running across the insulation space 43. Alternatively, a laminated wood product such as plywood may be used as the supporting members. Alternatively the supporting member or members 52 may be made from plate steel having through holes to allow fasteners such as nails or screws to fix the supporting member or members to the top of the stacks of boards 47, 48. Alternatively, the supporting member 52 and the bracket 50 may be integrally formed, however this is not 20 preferred. The preferred bracket embodiment of Figure 8 may be used at the top of the wall 49 and at the base of the wall 49. An embodiment having an integral bracket and supporting member could not be used at the lower end of the tie rod without modifying the bottom boards 42, as this bracket would be too wide to fit between the two stacks of boards. Further, the preferred bottom bracket secures the wall to the foundation floor or slab. The alternative 25 embodiment having an integral bracket and supporting member could be used to secure the brace assembly to the bottom boards, instead of the base platform supporting the wall. A preferred embodiment of the bracket 50 is shown in Figure 8A and Figure 8B. Bracket 50 preferably has a central curved portion 60 bridging between two flange portions 61. A hole or holes 62 are provided through the flange portions for fixing the bracket to the base 30 platform 40 or the supporting timber 52. A nail pattern of holes may be provided through flanges 61 for fixing the bracket to the supporting member with nails. In the preferred embodiment, bracket 50 is fixed to the supporting member with at least one coach screw or bolt through each flange 61. Preferably one hole is provided in each flange suitable for a suitable bolt. Typically the bolt could have a 12mm - 13mm shank diameter. The bracket 50 may include a 35 gusset 64 to provide additional strength to the curved portion 60. 19 WO 2009/136800 PCT/NZ2009/000069 In an alternative form of the bracket located at the top of the wall 49, flanges 61 may be wider than the central curved portion 60, the flanges extending to a width bridging the two stacks of boards. In this embodiment, the bracket is fixed directly to the upper edge of the two stacks of boards without a requirement for the support member 52. 5 The bracket 50 is preferably made from steel plate with a suitable plate thickness and coated with a corrosive resistance coating such as galvanised coating. Suitable plate thickness may be, for example, 6mm to 10mm. Preferably. the plate thickness is 10mm. A plate thickness of 10mm provides sufficient strength such that gusset 64 is not required. The tie rod 51 is preferably a steel bar with a circular cross section, the tie. rod having a 10 length suitable for extending between the bracket fixed at the base platform and the corresponding bracket fixed at the top of the wall. Each end of the tie rod is threaded, with a hexagon nut being threaded onto each threaded end of the steel bar. Alternatively, one end of the tie rod may be threaded with a nut fitted, the other end having an integrally formed hexagon head with an across flats dimension greater than the diameter of the tie rod cross section, the tie 15 rod effectively forming a very long bolt. A similar construction can be achieved by welding a nut in place to one end of the tie rod. Preferably the tie rod has a diameter of 10mm. In this specification and claims, the term hexagon is intended to include other shapes such as a square profile or any other profile to which a spanner may interface for tightening and loosening the bracing assembly components. 20 A slot 63 is provided in the central curved portion 60 of the bracket 50. As best shown in Figure 9A, the tie rod is attached to the bracket by passing an end of the tie rod through the slot, and threading a nut 53, 54 onto the end of the tie rod once the tie rod is passed through the slot 63. At the bracket fixed at the top of the wall, a nut 53 threaded onto the tie rod end bears against the outer convex surface of the curved portion 60. At the bracket fixed at the base 25 platform, a nut 54 threaded onto the end of the tie rod 51 bears against the inside concave surface of the curved portion 60. The nut at the upper end of the tie rod and the nut at the lower end of the tie rod are tightened to achieve a desired level of tension in the tie rod, bracing the wall 49. Excess tie rod length may not be taken up by the nut and thread at the lower end of the 30 tie rod, as the tie rod end cannot extend into the base platform 40. In this instance, excess tie rod length is taken up by the thread and nut at the upper end of the tie rod. Alternatively, in the alternative embodiment of a tie rod having a fixed head at one end, the head end is preferably located at the lower bracket 50; excess tie rod length may be taken up by turning the nut at the upper end, or by turning the entire tie rod from the head at the lower end. 20 WO 2009/136800 PCT/NZ2009/000069 The flanges 61 of the bracket 50 are aligned with each other and are parallel to a diameter 68 of the curvature 66 of the curved portion 63, the curvature 66 of the curved portion having a centre 65. Preferably the flanges are spaced a distance 67 from diameter 68 so that the bracket 50 has a reduced height compared to if the flanges were placed diametrically on curvature 5 66. The slot 63 is preferably a circumferential slot extending around the central curved section. The length of slot 63 is sufficient to allow clearance for the tie rod 51 for a bracing angle A as shown in Figure 9A, of at least 33 degrees. The brackets are designed such that a centreline of the tie rod 51 may extend through the centre of curvature 65 of the curved section 60 of each 10 bracket 50, so that the tie rod extends radially through the curved section 60, the nut 53, 54 bearing tangentially against the curved section 60. For a long wall, the bracing is arranged as shown in Figure 7A(ii), with an angel A of approximately 33 degrees. For shorter walls, a smaller angle A is used and/or tie rods may be overlapped, as shown in Figures 7B and 7C. In the case of overlapping tie rods, the brackets 50 are offset to opposite sides of the centre of the insulation 15 cavity 43 of the wall 49 so that the overlapping tie rods do not clash. Preferably, the tie rods extend from an upper corner area of the wall 47 at an angle to the vertical. For long walls as shown in Figure 7A(ii), the bracing extends from the upper corners to be fixed at the base at a position distal from the ends 45 of the wall. The bracket of Figures 8A and 8B is rotationally symmetrical about 180 degrees. 20 In the most preferred embodiment of Figure 8C, the bracket 50 is not rotationally symmetrical. The slot 63 extends from adjacent a central position of the curved section 60 to one side of the central position. Preferably the circumferential slot extends around the central curved section, on one side of the vertical axis 59 of the bracket only, to allow clearance for the tie rod 51 for a bracing angle A, as shown in Figure 9A, of approximately 15 degrees to 35 25 degrees. In this embodiment, the bracket must be oriented correctly within the wall to allow the tie rod to be angled in the required direction within the wall. Alternatively the slot may include a wide section, or key hole, to allow the fixed head or nut of the tie rod assembly to pass through. For example the key hole could be located at one end of the slot. Alternatively, the key hole could be located centrally to allow angled bracing, 30 with the tie rod being coupled to the bracket to one side of the key hole. With reference to the tie rod embodiment with a fixed head at the lower end, the key hole allows the fixed head to pass through the central curved section. The tie rod is engaged to the bracket by sliding the tie rod from the key hole and along the slot, the width of the slot being narrower than the extent of the fixed head. 21 WO 2009/136800 PCT/NZ2009/000069 Depending on the length of a wall, the tie rod may cross one or more vertical members 44. The vertical members 44 have cut outs through which the tie rods may pass. Alternatively the tie rod may pass between the ends of vertically adjacent vertical members that are spaced apart for this purpose. 5 A washer may be used between the nut 54 and the bracket 50 at the lower end of the tie rod. The washer may have or deform to have a convex bearing surface to match the concave surface of the bracket 50. Similarly, a washer may be used between the nut 53 and the bracket 50 at the upper end of the tie rod. The washer may have or deform to have a concave bearing surface to match the convex surface of the bracket 50. 10 For the embodiment of the tie rod having a fixed head at the lower end of the tie rod, the nut 53 at the upper end of the tie rod 51 may have a curved bearing surface 55 in contact with the curved portion 60, the curved bearing surface 55 having a radius of curvature corresponding to the radius of curvature of the curved section 60 of the bracket. The curved surface 55 of nut 53 interfaces with the convex curvature of the curved portion 63, acting to 15 prevent rotation of nut 53 as tie rod 51 is rotated when tightening tie rod 51 to brace the wall 49. The fixed head preferably has an across flats dimension greater than the width of the slot 63, coupling the tie rod directly to the bracket. Alternatively, the head may have an across flats dimension less than the width of the slot, the tie rod end being indirectly coupled to the bracket by a washer between the bracket and the head, the washer being wider than the slot 63. 20 In the preferred embodiment of Figure 9B, the bracket at the upper end of the tie rod is oriented with the central curved portion extending downwards. In this arrangement, the upper end and lower end of the tie rod interfaces to the corresponding bracket 50 in the same way, with the nut 53, 54 being captured within the bracket on the convex side of the bracket. In the preferred embodiment of Figure 9B, a washer 35 may be used between the bracket 50 and the 25 nut 53, 54. During the construction of the wall 49, the tie rod may be fitted to the lower bracket at the time the lower bracket 50 is fixed to the base platform. The tie rod will rest in place as each stack of boards is assembled. Alternatively the tie rod may be inserted after assembly of some or all of the stack of boards. 30 Once the two stacks of boards are completed, the bridging timber 52 is fixed to the top of the board stacks, either by nailing, screwed or bolted connection. To gain access to the nut or head at the lower end of the tie rod, a rebate is provided in the board 42 of the inside stack at the base platform 40. The rebate is indicated by line 69 in Figures 12A and 12B. The rebate may be easily concealed by a skirting board 70 fixed against the 35 base of the wall 49 at the base platform 40. 22 WO 2009/136800 PCT/NZ2009/000069 The tie rods 51 brace wall 49. The tie rods also act as a hold downs, tightening boards 42, 46 downwards, and further securing the wall onto the base platform 40. The tie rods may be installed substantially vertically, acting as tie downs to secure the wall to the base platform. The wall may include tie rods at any angle A from Odegrees to around 40 degrees. 5 Preferably each braced wall section includes a pair of brace assemblies acting from opposite directions. In this way, horizontal shear forces in the stacks of boards created by one tie rod should be substantially balanced by the forces created by the other tie rod. And the panel is braced against shear from either direction. According to a further invention herein, the bracing assembly consists of at least a tie 10 rod 51, upper and lower brackets 50 and upper and lower nuts 53, 54. The bracing assembly may also include a spring 56, as shown in Figure 10. Washers 57, 58 also may be included at each end of the spring. The washer 57 between the spring and the bracket 50 may have a concave bearing surface to match the convex surface of the bracket 50. In the embodiment of Figure 9B, the spring would be located between washer 35, and a second washer 58 as shown in Figure 10, 15 before nut 53 is threaded onto the upper end of the tie rod. The wall 49 of the present invention may be constructed with boards 42, 46 having moisture content. Once a building construction is completed and waterproofed, any moisture in the boards 42, 46 will evaporate over time as the boards dry out. As the boards dry out, the boards may shrink slightly. As the drying boards shrink, tension in the tie rods decreases and the 20 tie rod nuts 53, 54 may need to be retightened to achieve the desired level of tension. The spring 56 mitigates this problem by maintaining tension in the tie rod as the boards shrink. A suitable spring has been shown to be of 70 mm free length, with a spring rate of 50N/mm. A building having a traditional timber construction has a timber frame comprising vertical studs and horizontal nogs. Timber weatherboard cladding is applied to the exterior side 25 of the timber frame, and an internal lining, typically plasterboard, is applied to the interior side of the timber frame. Insulation material is installed within the timber frame, in between vertical studs and horizontal nogs, prior to adding the internal lining. The studs and nogs and lintels for doors and windows result in bridging between the external cladding and the internal wall lining. where there is no insulation material. The studs and nogs provide areas of contact between the 30 external and internal wall linings through which heat transfer may occur more easily compared to insulated areas of the wall. Due to the dimensions of the timber studs and nogs and the thermal conductivity of wood, the bridging provided by the studs and nogs between the inner lining and the exterior cladding results in a relatively large area (10% or greater of the wall area) of relatively high thermal conductivity. 23 WO 2009/136800 PCT/NZ2009/000069 The wall system of the present invention allows a building to be constructed with a minimal amount of bridging between the two stacks of boards. Figure 1 1A is a plan view of a corner section of the wall system of the present invention. Bridging between the exterior stack of boards 48 and the interior stack of boards 47 occurs via the vertical members 44 only. Vertical 5 members 44 are very thin so that thermal bridging between the two stacks of boards is kept to a minimum. Additionally, and according to a further invention herein, the wall system of the present invention allows the insulation space 43 between the two stacks of boards 47, 48 to be continuous around a vertical corner section of a building. In prior art building construction, 10 structural components such as columns or studs required at the corners of a building results in relatively high thermal bridging at the corners of a building compared to a building constructed with the wall system of the present invention. A building may be constructed with walls of the present invention, without additional support structure such as columns or studs within the insulation space between the two stacks of boards, thus thermal bridging is kept to a minimum, 15 even at corner sections of the building. As shown in Figure 1 1A, the interior stack of boards 47 and the exterior stack of boards 48 of one wall are joined or locked to the interior stack of boards 47 and the exterior stack of boards 48 of another wall via locking members 41. The external corner between the exterior stacks of boards may be formed with a mitre joint and covered with a soaker 39, or any other 20 suitable joining method may be used at the external corner. In the preferred embodiment of Figure 11 B, a joining corner extrusion 38 is used to complete the corner joint between the two exterior stacks of boards. Extrusion 38 is preferably extruded from aluminium, but may be extruded from other suitable materials, for example suitable plastics such as polypropylene., Each exterior stack of boards 48 is joined to the corner extrusion by a connection member 36. Vertical 25 grooves 15, the same or similar in profile to the grooves 16 cut in the side faces of the boards 42, 46, are cut into the end edges of the boards during performing of the boards at an offsite location by the board manufacture. The corner joint is completed once the stacks of boards have been assembled. Corner extrusion 38 is placed in position between the ends of the exterior stacks of boards 48. The corner extrusion has two vertical channels, each channel being aligned to a 30 corresponding vertical groove 15. Two connection members are used to connect the corner extrusion 38 to the end edges of the exterior stacks of boards 48. Each connection member 36 has a retaining portion 35 and a lug 34. Each connection member is slid into place, preferably from above the walls 49. The retaining portion is received within a vertical groove 15. The lug 34 slides into a corresponding vertical channel in the corner extrusion. Additional flashing 24 WO 2009/136800 PCT/NZ2009/000069 extrusions 37 slide, preferably from above the corner assembly, into corresponding channels of the corner extrusion 38, to weatherproof the corner connection assembly. To form the joint between the interior stacks of boards, the end edge of one stack of boards is butted against a side face of the other stack of boards. An end groove 15 in the end 5 face of the boards of one stack is aligned with a groove 16 in the side face of the boards of the other stack. A locking member 41 slides, preferably from above, into the corresponding grooves 15, 16 to lock the interior stacks of boards together, as shown in Figure 1 1B. A recess 33 may be cut into the corresponding side face of the interior stack of boards 47 to receive the end edge of the interior stack of boards 147. Recess 33 is preferably machined into the individual boards 10 during pre-forming of the boards at an offsite location by the board manufacture. Alternatively, once a base board 42 of each stack of boards is in place, locking member 41 may be located in grooves 15, 16 of the base board 42. Additional boards 46 may be slid onto the locking members from above, until the two stacks of boards are completed. An improved building construction utilising the wall system of the present invention is 15 shown in Figures 12A and 12B. According to another invention herein, insulation 79 extends from the wall cavity 43 to beneath an internal floor 69 of the base platform 40. In a traditional timber house, the base platform consisting of a frame of floor joist and noggings covered with a surface of floor boards or sheet material is typically supported by a plurality of spaced apart bearers, the bearers resting on piles extending into the ground beneath 20 the base platform. A boundary of the base platform is approximately aligned with a boundary of the building, including boundary piles being located directly beneath the boundary joists of the base platform. Timber framed walls are then built at the boundary of the base platform. An exterior side of the wooden framing of an exterior wall is approximately flush with the edges of the floor and a boundary joist of the base platform and ends of adjacent spaced apart bearers 25 arranged at right angles to the base platform joists. Load bearing external walls transfer load through the base platform boundary joists to the bearers and into the piles, with piles being located approximately directly beneath the base platform boundary joists. In the improved building construction of Figure 12A, the base platform is supported by a building support structure consisting of bearers 72 and piles 71. Bearers 72 are supported by 30 piles 71, the bearers 72 extending to a vertical boundary 80 of the building support structure. The base platform comprising a floor surface of floor boards or sheeting material 69, joists 73 and noggings 74 is supported on the bearers 72. The vertical boundary 80 of the supporting structure extends beyond a vertical boundary 81 of the base platform 40. The support structure includes an additional boundary joist 76 fixed to the bearers 72 at the vertical boundary 80. A 35 packer 75 is located between the boundary joist 76 and the bearers 72 so that an upper surface of 25 WO 2009/136800 PCT/NZ2009/000069 the boundary joist 76 is aligned with the surface of the base platform 40. Alternatively the packer may be located between the boundary joist 76 and stack of exterior boards 48. Alternatively, a boundary joist with a deeper section may be used. The wall system of the present invention is assembled above the base platform and the building support structure. The interior stack of 5 boards 47 are arranged at the vertical boundary 81 of the base platform 40, the stack of boards having a surface facing the exterior stack of boards, the surface being aligned with the vertical boundary 81 of the base platform. The exterior stack of boards 48 are arranged at the vertical boundary 80 of the building support structure, so that the internal cavity 43 of the wall system of the present invention spans the gap between the boundary joist 76 and the base platform 40, 10 effectively extending the wall cavity to below the floor level 69 of the base platform. To provide support for a tie rod arrangement (vertical tie rods or bracing tie rods as described earlier), a tie rod nog 77 may be fixed adjacent to the boundary joist 76. Tie rod bracket is fixed to the tie rod nog in the same way as the bracket is fixed to the base platform as described earlier. The tie rod nog is preferably 600mm long and is securely fixed to the boundary 15 joist 76. The improved building construction of Figure 12A is shown in Figure 12B, viewed at right angles to the view of Figure 12A. In Figure 12B, the base platform vertical boundary 80 is defined by the extent of the noggins 74 and floor surface 69; the base platform joists 73 extend beyond the vertical boundary of the flooring 69 and noggings 74. A boundary joist 78 is fixed to 20 the ends of the base platform joists 73, an upper surface of the boundary joist 78 being aligned with the floor surface 69. The interior stack of boards 47 is arranged at the vertical boundary of the base platform 81, and the exterior stack of boards is arranged at the vertical boundary 80 of the support structure, as described in relation to Figure 12A, such that the internal cavity 43 of the wall system 49 of the present invention extends below the floor level 69 of the base platform, 25 in between the base platform joists 73. The improved construction of Figure 12A and 12B allows insulation 79 in the wall cavity 43 to extend downwards below the level of the base platform noggings 74, the insulation being provided between the base platform joists 73 and extending under the floor surface in between and/or beneath the base platform noggings 74. The improved building construction 30 achieves reduced bridging between the exterior of the building and the interior of the building, between the interior and exterior stacks of boards to a level below the interior floor level 69, and under the interior floor level 69. As shown in Figures 12A and 12B, the boards 42 at the base of the interior stack of boards and the exterior stack of boards are preferably fixed to the base platform by fixing 35 brackets 85 and 86. Horizontal flanges of brackets 85, 86 are preferably fixed to the base 26 WO 2009/136800 PCT/NZ2009/000069 platform with nails or screw fasteners through holes or slots (not shown). The horizontal edges of the boards 42 rest between vertical flanges of brackets 85, 86. The boards 42 are fixed to the brackets via the vertical flanges with nails or screw fasteners through holes or slots (not shown) in the vertical flanges. 5 According to another invention herein, the wall system may be utilised above a split roof, as shown in Figure 13A and Figure 13B. Bracket 90 is used to support at least a portion of the exterior stack of boards 48. A first side of bracket 90 is fixed with nails or screw fasteners 91 to a side of a board 38, the side of the board 38 intended to face the interior stack 47. A second side of the bracket 90 is then fixed with nails or screw fasteners to the interior stack of boards 47, 10 positioning at least a portion of board 38 above the split level roof 82. The second side of the bracket 90 may be fixed to bridge over two boards of the interior stack 47, as shown in Figures 13A and 13B. At least one bracket is required per board 38, to support at least a portion of the board 38 above the split level roof., The board 38 may have a portion located above a split level roof 15 and a portion located in the exterior stack of boards extending to the base platform. The portion of the board 38 located within the exterior stack of boards extending to the base platform does not require brackets 90 for support. The portion of the board 38 located above the split level roof may have one or more brackets 90 to support board 38, and additional boards 46 stacked above board 38, above the split level roof. Where more than one bracket is used, the brackets 20 may be spaced apart by approximately 1m. Board 38 may need to be cut to match the roof line of the split level roof 82 prior to installation. The cutting of board 38 to match the roof line is project specific and may be done on-site during construction of a building. Once the at least one bracket 90 and the board 38 have been installed above the split level roof 82, additional boards 46 may be stacked above board 38 25 to complete the exterior board stack 48. Additional boards 46 stacked above board 38 may also include a portion above the split level roof without boards below, and will also require at least one bracket 90 for support. Typically, where the roof line of a split level roof is inclined on the face of the exterior wall 48, board 38 requires one bracket 90 at the end of the board above the split level roof, where 30 the board is cut to match the roof line. Typically, where the roof line of a split level roof is substantially horizontal on the face of the exterior wall 48, board 38 requires more than one bracket 90 spaced apart. Bracing 58 as shown in Figures 9A or 9B may be applied to the wall above a split level roof. A suitable base member (not shown) is supported by the brackets 90. The base member 35 rests on the central member of brackets 90 and is fixed to the central member via through holes 27 WO 2009/136800 PCT/NZ2009/000069 (not shown) in the central member of bracket 90. Tie rod brackets are fixed to the base member supported by the brackets 90 as described previously. The remainder of the brace assembly is installed as described in relation to Figures 9A and 9B. Insulation 79 may be installed behind board 38 and under bracket 90 prior to fixing 5 bracket 90 to the interior stack of boards 47. Alternatively, insulation 79 may be added after the board 38 and brackets 90 have been installed. For example, a block or blocks of insulating material may have slots of material removed in positions relating to the positions of brackets 90, so that the insulation may be installed from above brackets 90, with slots in the insulating material aligned with brackets 90 so that the insulating material extends either side of each 10 insulating bracket to below the brackets 90 and behind the bottom board 38. Once the board 38, bracket 90 and insulation 79 are in place, a flashing 83 is installed behind the exterior stack of boards 48 to interface with roof material 84 such as roofing tiles or sheet metal roofing products. In the slightly different alternative embodiment of Figure 13B, vertical battens 93 are fixed to the exterior surface of the exterior stack of boards 48. Exterior 15 cladding, in this example being exterior weatherboards, is fixed to the vertical battens. Flashing 83 extends vertically to locate between the exterior board stack 48 and the battens 93. A preferred form of bracket 90 is shown in Figures 14A and 14B. Bracket 90 is preferably fabricated from steel plate of suitable thickness. The plate may have a thickness of 5mm, and coated with a corrosive resistance coating such as galvanised coating. Bracket 90 has a 20 first flange 92 and a second flange 96. The first and second flanges are parallel and spaced apart. Once installed within the wall system of the present invention, the first and second flanges are substantially vertical. The first and second flanges extend from opposite sides of a central member 93. The bracket may be rotationally symmetrical about 1 80degrees so that correct orientation is easier to achieve. A web 94 may be located within the interior angle formed 25 between the first flange and the central member, the web extending at least partway across the central member and at least part way across the first flange.. A web. 97 may be located within the interior angle formed between the second flange and the central member, the web extending at least partway across the central member and at least part way across the second flange. Each web 94, 97 is preferably arranged normal to the central member and the corresponding flange. Webs 30 94, 97 brace the central member relative to each flange. Preferably the webs 94, 97 extend substantially the full width of the central member from flange to flange. The angle between each flange and the central member is preferably around 90degrees. The first and second flanges each have a plurality of holes 95 for fixing the first and second flanges within the wall system of the present invention. Holes 95 are sized to allow 35 fasteners 91 to be applied to the interior stack of boards 47 at an angle so that fasteners 91 and 28 WO 2009/136800 PCT/NZ2009/000069 necessary fastener tooling clear the upper edge of the board 38 when fixing the second flange of the bracket to the interior stack of boards. As described previously, central member 93 may include holes (not shown) for fixing a base member (not shown) to bracket 90, base member providing support for a bracing assembly 53. 5 The interior stack of boards 47 below the split level roof and extending from a base platform is supported by the interior boards of other walls joined to interior stack 47. For example, as shown in Figure 15, an internal corner section 100 of a building is formed with two walls of the present invention, walls 101 and 102. Wall 101 comprises an interior stack of boards 47 and an exterior stack of boards 48. Wall 102 comprises an interior stack of boards 147 and an 10 exterior stack of boards 148. Interior stack of boards 47 could relate to the interior stack of boards of Figures 13A and 13B, extending from a base platform to a height above a split level roof. Interior stack of boards 147 provides lateral support to interior stack of boards 47 as shown in Figure 15. Additional interior support columns (not shown) may be incorporated into the building 15 construction to provide lateral support to any interior stack of boards 47. Interior support columns are connected to a side face of interior stack of boards 47 in a similar manner as the connection between interior stacks of boards 47, 147. The column may include a vertical groove (like groove 15 in Figure 15) machined into one side face corresponding to a vertical groove (like groove 16 in Figure 15) in a side face of the stack of boards 47. The wall 47 and an internal 20 column are joined with a connection member (like locking member 41 in Figure 15) located in the corresponding vertical grooves. A recess may be cut in a side face of the stack of boards 47 to receive an internal support column. Preferably the elements of the wall system are provided in the form of a kitset combining a collection of preformed wall boards and the complementary vertical members. 25 Most preferably the kitset further comprises connection members, brackets, tie rods and other associated components of the wall system. The wall system of the present invention has an exterior wall having a solid wood interior wall portion, a solid wood exterior wall portion and a substantial insulation gap therebetween. The form and manner of engagement of the components of the wall system 30 ensures a strong and rigid structure after assembly. Yet the components, which are intended to be preformed at an offsite location, are provided in a form that does not occupy excessive space during transport. An insulation gap is formed in the assembly stage onsite rather than in the manufacture stage at the factory. Furthermore, the wall system of the present invention allows an improved building 35 construction with a reduced amount of thermal bridging between the interior and exterior wall 29 WO 2009/136800 PCT/NZ2009/000069 linings, and provides for an insulation space that extends from a cavity between the inner and outer wall linings to below the floor level of the building and around a corner section of a building from one wall to another. Insulation may extend from the wall cavity to under the floor of the building, resulting in a building with improved insulation properties. 5 30

Claims

1. A wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the 5 longest dimension, the height being less than the length, and the thickness being less than the height, said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, and 10 vertical members rigidly spacing each said stack of boards at spaced locations along said wall, each said vertical member having a spanning portion between the interior and exterior stacks of boards, a retainer, associated with a first vertical edge, engaged in a vertical slot, having a complementary horizontal cross-section to said retainer, in said inner face of one stack of boards, and a retainer, associated with its other vertical edge, engaged in a slot, having a 15 complementary horizontal cross-section to said retainer, formed in the inner face of the other stack of boards, such that said interior and exterior stacks of boards are spaced apart by the width of said spanning portion, which extends across the height of a plurality of boards of each said stack of boards. 20

2 A wall as claimed in claim 1 wherein said spanning portion at least is formed of a material having a thermal conductivity similar to or less than a plastic material such as polypropylene.

3. A wall as claimed in claim 2 wherein said spanning portion is formed from a plastic 25 material such as polypropylene.

4. A wall as claimed in claim 1 wherein said vertical member may be formed as a unitary element including said retainers together with said spanning portion. 30

5. A wall as claimed in claim 1 wherein said vertical member comprises a plurality of said retainers, in use the retainers being connected with the vertical edges of said spanning portion and engaged in said slots of said interior and said exterior stack of boards.

6. A wall as claimed in claim 5 wherein the retainers are formed from the same material as 35 said spanning portion. 31 WO 2009/136800 PCT/NZ2009/000069

7. A wall as claimed in claim 5 wherein the retainers are formed from aluminium extrusions. 5

8. A wall as claimed in any one of claims 7 wherein said retainers are a fraction of the length of the vertical member, there being a plurality of retainer engaged along each respective edge of said spanning portion.

9. A wall as claimed in claim 1 wherein said vertical member includes stiffening flanges or 10 ribs at intervals along the height of said spanning portion, said flanges extending laterally from said spanning portion and laterally across the width of said spanning portion.

10. A wall as claimed in claim 9 wherein the flanges or ribs may be integrally formed with the spanning portion. 15

11. A wall as claimed in claim 1 wherein said spanning portion of said vertical member includes one or more cut-out regions.

12. A wall as claimed in claim 1 wherein said slot of each said stack of boards comprises a 20 dovetail mortise having a tapered neck substantially at the inner surface of the stack of boards and a broader portion extending into the stack of boards to a depth part way through the thickness of the stack of boards.

13. A wall as claimed in claim 12 wherein the dovetail mortise is formed by a pair of 25 intersecting cuts, each cut extending beyond the intersection to create the dovetail, with the intersection of the cuts creating the tapered neck of the slot.

14. A wall as claimed in claim 12 wherein the retainers of said vertical member comprise narrow flanges extending into divergent parts of said dovetail mortise from a common base 30 portion residing in said intersection of said cuts.

15. A wall as claimed in claim 1 wherein said gap between said interior and exterior stacks of boards is at least 80mm. 32 WO 2009/136800 PCT/NZ2009/000069

16. A wall as claimed in claim 15 wherein the gap is greater than 100mm, but less than 300mm.

17. A wall as claimed in claim 1 wherein the wall includes a plurality of said vertical 5 members at regularly spaced intervals along the wall.

18. A wall as claimed in claim 1 wherein said wall includes insulation material having a high thermal resistance (low thermal conductivity) substantially completely occupying the space between said interior and exterior stacks of boards in the regions between adjacent vertical 10 members.

19. The wall as claimed in claim 1 wherein the wall further comprises at least one brace assembly, the brace assembly comprising: a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom 15 portion of the wall, a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and 20 at least one tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level, the tie rod being located between the two spaced apart stacks of boards.

20. The wall as claimed in claim 19 wherein the tie rod extends at an angle of approximately 25 50 degrees to 90 degrees relative to the length of the boards.

21. The wall as claimed in claim 19 wherein the tie rod extends at an angle of approximately 55 degrees to 75 degrees relative to the length of the boards. 30

22. The wall as claimed in any one of claims 19 to 21 wherein the wall includes two said brace assemblies, the two brace assemblies acting from opposite directions such that horizontal shear forces in the stacks of boards created by one brace assembly are substantially balanced by the horizontal shear forces in the stacks of boards created by the other brace assembly. 33 WO 2009/136800 PCT/NZ2009/000069

23. The wall as described in any one of claims 19 to 22 wherein the first end and the second end of the tie rod are threaded, the tie rod passing through slots in the first and second brackets, a first nut is threaded onto the first end to couple the first end directly or indirectly to the first bracket, and a second nut is threaded onto the second end to couple the second end directly or 5 indirectly to the second bracket, the first nut and corresponding thread, or the second nut and corresponding thread, or both, acting as the tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level by relative rotation between the first nut and the tie rod and second nut, or by relative rotation between the second nut and the tie rod and first nut. 10

24. The wall as described in any one of claims 19 to 22 wherein the first end has a fixed head for interfacing with a spanner and the second end is threaded, the tie rod passing through slots in the first and second brackets, the head coupling the first end directly or indirectly to the first bracket, and a nut being threaded onto the second end to couple the second end directly or 15 indirectly to the second bracket, the nut and the corresponding thread acting as the tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level, the tensioning mechanism being actuated by relative rotation between the nut and the tie rod. 20

25. The wall as claimed in any one of claims 19 to 24 wherein the first bracket or the second bracket, or both, comprises a central curved portion and two flange portions, the central curved portion bridging between the two flange portions, the two flange portions being aligned on a plane, each flange portion having at least one through hole for fixing the bracket via the two flange portions to a corresponding surface or surfaces, with a slot in the central curved portion 25 for receiving the tie rod.

26. The wall as claimed in claim 25 wherein the flange portions extend parallel to a diameter of the curvature of the curved portion, the flange portions being spaced a distance from the diameter towards the central curved portion. 30

27. The wall as claimed in claim 25 or claim 26 wherein the slot is circumferential and extends through an arc of at least 40 degrees.

28. The wall as claimed in claim 27 wherein the slot is located to a first side of the central 35 curved portion only, and a second side of the central curved portion is without a slot. 34 WO 2009/136800 PCT/NZ2009/000069

29. The wall as claimed in any one of claims 25 to 28 wherein the bracket includes a gusset, the gusset extending across a portion of the central curved portion, the gusset being arranged substantially normal to an axis of the curvature of the central curved portion. 5

30. The wall as claimed in any one of claims 19 to 29 wherein the wall includes at least one supporting member fixed to a top surface of the interior stack of boards and the exterior stack of boards, the supporting member bridging across the space between the interior stack of boards and the exterior stack of boards, and the second bracket is fixed to the supporting member. 10

31. The wall as claimed in any one of claims 25 to 29 wherein the flange portions of the second bracket are wider than the central curved portion, the flange portions extending to a width bridging the interior and exterior stacks of boards, the bracket being fixed via the flange portions to a top surface of the interior stack of boards and the exterior stack of boards. 15

32. The wall as claimed in any one of claims 25 to 30 wherein the first and second brackets have the same dimensions.

33 The wall as claimed in any one of claims 25 to 32 wherein the first bracket is oriented 20 with the curved portion upwards, and the second bracket is oriented with the curved portion downwards.

34. The wall as claimed in any one of claims 19 to 33 wherein the brace assembly includes a resilient element for maintaining tension in the tie rod. 25

35. The wall as claimed in any one of claims 19 to 34 wherein a bottom board at the base of a wall stack has an access hole, the access hole passing through the thickness of the board to provide access to the first end of the tie rod. 30

36. A building construction constructed from at least two walls as claimed in claim 1 or claim 19, the at least two walls intersecting, an interior stack of boards of a first wall being joined to an interior stack of boards of a second wall, and an exterior stack of boards of the first wall being joined to an exterior stack of boards of the second wall, such that an insulation space of the first wall communicates with an insulation space of the second wall to create a corner insulation 35 WO 2009/136800 PCT/NZ2009/000069 space extending around the corner between the first and second walls and substantially the height of the first and second walls.

37. The building construction as claimed in claim 36 including insulation in the comer 5 insulation space, the insulation extending continuously between the first and second walls.

38. The building construction as claimed in claim 36 or 37 wherein an end edge of the interior stack of boards of the first wall has a vertical groove extending the height of the wall, and a side of the interior stack of boards of the second wall has a corresponding vertical groove near 10 an end of the second wall extending the height of the second wall, the first and second walls arranged to butt the end edge of the interior stack of boards of the first wall against the side of the interior stack of boards of the second wall, aligning the vertical grooves of the interior stacks of boards of the first and second walls, and a locking member having a retainer associated with a first vertical edge, engaged in one 15 of said vertical grooves, having a complementary horizontal cross-section to said retainer, and a retainer associated with its other vertical edge, engaged in the other said vertical groove, having a complementary horizontal cross-section to said retainer, such that said locking member locks the interior stacks of boards of the first and second walls together. 20

39. The building construction as claimed in any one of claims 36 to 38 wherein the building construction including a corner member having a first side and a second side, the first and second sides being at right angles to one another, the corner member extending the height of the walls, and wherein an end edge of the exterior stack of boards of the first wall has a vertical groove 25 extending the height of the first wall and an end edge of the exterior stack of boards of the second wall has a vertical groove extending the height of the second wall, and the corner member has a vertical channel in the first side extending the height of the first wall and a vertical channel in the second side extending the height of the second wall, and an end edge of the exterior stack of boards of the first wall butts against the first side of 30 the corner member, aligning the vertical groove with the vertical channel in the first side, and an end edge of the exterior stack of boards of the second wall butts against the second side of the corner member, aligning the vertical groove with the vertical channel in the second side, and wherein the building construction further includes two connecting members, each connecting member having a retainer associated with a first vertical edge, said retainer engaged in 35 one of said vertical grooves, said vertical grooves having a complementary horizontal cross 36 WO 2009/136800 PCT/NZ2009/000069 section to said retainer, and said connecting member having a lug associated with its other vertical edge, said lug engaged in a corresponding one of said vertical channels, said vertical channels having a complementary horizontal cross-section to said lug, such that said connecting members lock the exterior stacks of boards of the first and second walls to the corner member. 5

40. A building construction constructed from at least one wall as claimed in claim 1 or claim 19, the at least one wall being assembled on a base platform, the base platform being supported by a building support structure, wherein a vertical boundary of the building support structure extends beyond a vertical boundary of the base platform, 10 the interior stack of wall boards being stacked at the base platform vertical boundary, and the exterior stack of wall boards being stacked at the building support structure vertical boundary, the space between the interior stack of boards and the exterior stack of boards spanning a gap between the base platform vertical boundary and the building support structure 15 vertical boundary, the space communicating with the gap to create an insulation space extending from between the two stacks of boards downwards between the base platform vertical boundary and the building support structure vertical boundary to below a floor level of the base platform.

41. The building construction as claimed in claim 40 including insulation in the insulation 20 space, the insulation extending continuously from between the interior and exterior stacks of boards to below the floor level of the base platform.

42. The building construction as claimed in claim 41 wherein the insulation extends continuously from between the interior and exterior stacks of boards to underneath at least a 25 portion of the floor level of the base platform.

43. The building construction as claimed in claim 41 or claim 42 wherein the base platform includes a floor surface, joists and noggings, and the insulation extends under the floor surface and noggings and between the joists. 30

44. The building construction as claimed in any one of claims 40 to 43 wherein the building support structure comprises boundary joists and bearers, the base platform being supported by the bearers, the boundary joists having an upper surface in plane with a floor surface of the base platform. 35 37 WO 2009/136800 PCT/NZ2009/000069

45. The building construction as claimed in any one of claims 40 to 44 wherein the first bracket is fixed to a nog, the nog being securely fixed to a said boundary joist.

46. A building construction constructed from at least one wall as claimed in claim 1 or claim 5 19 wherein the interior stack of boards is assembled on a base platform, the interior stack of boards extending to a height above a first roof level, and the exterior stack of boards includes at least one board having at least a portion above the first roof level, the portion being supported by at least one bracket fixed to the interior stack of boards at a position above the first roof level. 10

47. The building construction as claimed in claim 46 wherein the bracket comprises: a first flange and a second flange, the first and second flanges being parallel and spaced apart, in use the first and second flanges being substantially vertical, a central member, the first and second flanges extending from opposite sides of the central member, 15 the first and second flanges each having at least one hole, the first flange being fixed to the inner face of one said stack of boards by fasteners through said at least one hole and the second flange being fixed to the inner' face of the other said stack of boards by fasteners through said at least one hole. 20

48. The building construction as claimed in claim 47 wherein a first web is located within the interior angle formed between the first flange and the central member, the first web extending at least partway across the central member and at least part way across the first flange

49. The building construction as claimed in claim 47 or claim 48 wherein a second web is 25 located within the interior angle formed between the second flange and the central member, the second web extending at least partway across the central member and at least part way across the second flange.

50. The building construction as claimed in any one of claims 47 to 49 wherein the interior 30 angles are 90 degrees.

51. The building construction as claimed in any one of claims 47 to 50 wherein the holes are sized to allow fasteners to be applied to the inner face of the interior stack of boards at an angle so that the fasteners and necessary fastener tooling clear the upper edge of the bottom board 35 when fixing the bracket to the inner face of the interior stack of boards. 38 WO 2009/136800 PCT/NZ2009/000069

52. The building construction as claimed in any one of claims 46 to 51 wherein the portion of the board above the first roof level is supported by at least two said brackets, the at least two brackets being spaced by a spacing of approximately 1m. 5

53. The building construction as claimed in any one of claims 46 to 52 wherein the central member has through holes and the building construction further comprises: at least one base member fixed to the at least two brackets, the at least one base member being supported by and fixed to the central members via the through holes, 10 at least one brace assembly, the brace assembly comprising: a first bracket for fixing the brace assembly to said at least one base member, a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the 15 second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level, the bracing assembly being installed within the spacing between the two spaced apart stacks of boards. 20

54. A brace assembly for bracing a wall, the brace assembly comprising: a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom portion of the wall, a second bracket for fixing the brace assembly to a top portion of the wall, 25 a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level. 30

55. A bracket for a brace assembly comprising: a central curved portion and two flange portions, the central curved portion bridging between the two flange portions, the two flange portions being aligned on a plane, each flange portion having at least one through hole for fixing the bracket via the two flange portions to a 35 corresponding surface or surfaces, and a slot in the central curved portion. 39 WO 2009/136800 PCT/NZ2009/000069

56. A wall supporting bracket comprising: a first flange and a second flange, the first and second flanges being parallel and spaced apart, in use the first and second flanges being substantially vertical, 5 a central member, the first and second flanges extending from opposite sides of the central member, the first and second flanges each having at least one hole.

57. A wall comprising: 10 a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the height, said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an 15 inner face and an outer face, and at least one brace assembly comprising: a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom portion of the wall, a second bracket for fixing the brace assembly to a top portion of the wall, 20 a tie rod extending between the first and second brackets, a first end of the tie rod being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first, and second brackets to a predetermined tension level, 25 the tie rod being located between the two spaced apart stacks of boards.

58. A wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 30 height, said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, and two brace assemblies, each brace assembly comprising: 40 WO 2009/136800 PCT/NZ2009/000069 a first bracket for fixing the brace assembly to a base supporting the wall or to a bottom portion of the wall, a second bracket for fixing the brace assembly to a top portion of the wall, a tie rod extending between the first and second brackets, a first end of the tie rod 5 being coupled to the first bracket and a second end of the tie rod being coupled to the second bracket, and at least one tensioning mechanism for tensioning the tie rod between the first and second brackets to a predetermined tension level, the tie rod being located between the two spaced apart stacks of boards and 10 extending at an angle of 50 degrees to 75 degrees relative to the length of the boards, the two brace assemblies acting from opposite directions such that horizontal shear forces in the stacks of boards created by one brace assembly are substantially balanced by the horizontal shear forces in the stacks of boards created by the other brace assembly. 15

59. A building construction constructed from at least two walls, each wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 20 height, said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, the at least two walls intersecting, an interior stack of boards of a first wall being joined 25 to an interior stack of boards of a second wall, and an exterior stack of boards of the first wall being joined to an exterior stack of boards of the second wall, such that an insulation space of the first wall communicates with an insulation space of the second wall to create a corner insulation space extending around the corner between the first and second walls and the height of the first and second walls. 30

60. A building construction constructed from at least one wall, the at least one wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 35 height, 41 WO 2009/136800 PCT/NZ2009/000069 said boards arranged in an interior stack of boards and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, the at least one wall being assembled on a base platform, the base platform being 5 supported by a building support structure, wherein a vertical boundary of the building support structure extends beyond a vertical boundary of the base platform, the interior stack of wall boards being stacked at the base platform vertical boundary, and the exterior stack of wall boards being stacked at the building support structure vertical 10 boundary, the space between the interior stack of boards and the exterior stack of boards spanning a gap between the base platform vertical boundary and the building support structure vertical boundary, the space communicating with the gap to create an insulation space extending from between the two stacks of boards downwards between the base platform vertical boundary and the building support structure vertical boundary to below a floor level of the base platform. 15

61. A building construction constructed from at least one wall, the at least one wall comprising: a plurality of boards, each having a length, a height and a thickness, the length being the longest dimension, the height being less than the length, and the thickness being less than the 20 height, said boards arranged in an interior stack of boards-and an exterior stack of boards, the interior and exterior stacks of boards parallel and spaced apart, each stack of boards having an inner face and an outer face, the interior stack of boards being assembled on a base platform, the interior stack of 25 boards extending to a height above a first roof level, the exterior stack of boards including at least one board having at least a portion above the first roof level, the portion being supported by at least one bracket fixed to the interior stack of boards at a position above the first roof level. 30

62. A method of building a wall comprising the steps of: placing a first wall member on edge on a base platform, erecting a vertical spacing member to be retained in a vertical orientation with a retainer portion associated with each vertical edge of said vertical spacing member engaging within a vertical slot on a face of said first wall member, 42 WO 2009/136800 PCT/NZ2009/000069 sequentially placing additional wall members to create two stacks, one either side of said vertical member with each wall member secured to the respective edge of said vertical member in like manner, with said retainer portions of said vertical spacing member retained in aligned slots of said wall members. 5

63. A method as claimed in claim 62 wherein the method includes erecting multiple said vertical members at spaced locations along the first said wall member before erecting said stacks of further wall members. 10

64. A method as claimed in claim 62 wherein said method includes initially arranging at least one wall member on either side of a gap sized to take said vertical spacing member, with slots of said wall members aligned across said gap.

- 65. A method as claimed in claim 62 wherein said method includes alternately connecting 15 retainer portions much shorter in length than the length of said vertical member to an edge of said vertical member and assembling additional wall members into said stack adjacent said edge.

66. A kitset for constructing a wall, said kitset comprising: a first set of boards, each having slots extending across a side face at equivalent locations 20 along said board, and a second set of boards, each having slots extending across a side face at equivalent locations along said board, and a spacer, whether unitary or an assembly, being longer than a combined width of a plurality of said boards, said spacer having retaining portions along either edge adapted for 25 engaging in said slots of said boards.

67. A wall board, the wall board being longer than its width, and wider than its thickness, and having a series of slots across one side face, the side face defined by the width and length of the wall member, the slots aligned perpendicular to the length dimension of the wall board and 30 each having a depth of part of the thickness of the wall board, the slots of said series being separated by at least 400mm.

68. A wall board as claimed in claim 67 wherein said slots have a narrow entrance portion and a broader internal portion. 35 43 WO 2009/136800 PCT/NZ2009/000069

69. A wall board as claimed in claim 68 wherein the broader internal portion may be singular or bifurcated.

70. A wall substantially as herein described with reference to and as illustrated by Figures 1 5 to7.

71. A brace assembly substantially as herein described with reference to and as illustrated by Figure's 9 and 10. 10

72. A bracket for a bracing assembly substantially as herein described with reference to and as illustrated by Figure 8.

73. A building construction substantially as herein described with reference to and as illustrated by Figures 11 to 13 and 15. 15

74. A wall supporting bracket substantially as herein described with reference to and as illustrated by Figure 14. 44