Abstract:
A thermally insulating wall construction ( 1, 100, 199, 200  or  300 ), a masonry panel ( 5 A,  513, 205 A,  20513, 305 A,  305 B) and a method of fabricating masonry panels are disclosed. The panels are fabricated by pouring lightweight concrete into a mould ( 201 ) which includes a former ( 227 ) preferably formed from egg carton cardboard, or similar. The former ( 227 ) is retained in situ. Film or foil ( 28, 228 ) in one or several layers is positioned in a cavity ( 12 ) formed between opposed panels to thereby create a plurality of thermal barriers in stagnant air. High thermal ratings for wall constructions are thereby able to be achieved.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a building panel and wall construction made therefrom. In particular, the invention relates to a thermally insulating wall structure which finds particular application in buildings constructed in areas having extremes of either hot or cold, or both.  
       BACKGROUND ART  
       [0002]     U.S. Pat. Nos. 5,667,190; 5,922,235; 6,186,469 and 6,186,469 (Scott/assignee Scott System Inc.) disclose a concrete panel of simulated brick appearance and various bracket devices for maintaining brick pavers in situ during formation of the concrete panel. Although such panels address problems caused by the scarcity of bricklayers, they do not address the thermal problems associated with conventional masonry structure.  
         [0003]     In particular, the increasing price of energy and greenhouse gas consideration mean that the consumption of energy in both heating and cooling dwellings must be reduced. As a consequence, conventional masonry walls (including both double brick and brick veneer construction) are unable to meet the thermal insulation specification required of modem construction. For example, a brick veneer wall has an R rating of approximately 0.45-0.47, and a double brick wall has an R rating of approximately 0.5-0.52. Even with fiberglass insulation batts installed in the cavity of a brick veneer wall the R rating is only increased to approximately 1.5-2.0. However, modem building specifications call for an R rating for walls of approximately 3 or better.  
       OBJECT OF THE INVENTION  
       [0004]     Many forms of thermally insulating wall construction have been proposed, however, in order to be practical not only must the level of thermal insulation be good, but the wall must be structurally strong and easy to construct. Unless a particular wall construction meets all three of these desiderata, it is unlikely to be commercially successful.  
         [0005]     The object of the present invention is to provide an improved wall construction which makes use of both the concept of a cavity wall, and also the thermally insulating properties of reflective sheets, for example those fabricated from metal foils or metal coated films.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with a first aspect of the present invention there is disclosed a thermally insulating wall construction comprising a pair of masonry panels each having an internal surface and an observable surface and being arranged with said internal surfaces facing each other to define an air cavity between said panels, said internal surfaces each having a plurality of recesses interspersed between protrusions, and said wall construction having at least one reflective sheet which extends between adjacent protrusions, and which is spaced from the interior of said recesses.  
         [0007]     In accordance with a second aspect of the present invention there is disclosed a method of fabricating a panel for use in the abovementioned wall construction, said method comprising the steps of:  
         [0000]     (i) creating a mould for said panel,  
         [0000]     (ii) placing a shaped former in said mould to form said recesses and protrusions,  
         [0000]     (iii) pouring a flowable hardenable cementitious substance onto said former within said mould and allowing same to set, and  
         [0000]     (iv) removing said set material and former from said mould whereby said former is retained in situ in said panel.  
         [0008]     In accordance with a third aspect of the present invention there is disclosed a masonry panel having an internal surface and an observable surface, said internal surface having a plurality of recesses interspersed between protrusions, and at least one reflective sheet which extends between adjacent protrusions and which is spaced from the interior of said recesses. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Several embodiments of the present invention will now be described with reference to the drawings in which:  
         [0010]      FIG. 1  is a schematic perspective cut away view of a wall constructed in accordance with the first embodiment of the present invention,  
         [0011]      FIG. 2  is a perspective view of the interior surface of either one of the panels from which the wall of  FIG. 1  is constructed,  
         [0012]      FIG. 3  is a substantially horizontal and transverse cross sectional view taken through the wall construction of  FIG. 1 ,  
         [0013]      FIG. 4  is a view similar to  FIG. 3  but of a second embodiment,  
         [0014]      FIG. 5  is a view similar to  FIG. 4  but showing a third embodiment,  
         [0015]      FIG. 6  is a vertical cross-sectional view through a mould used to form the panel of a fourth embodiment,  
         [0016]      FIG. 7  is a view similar to  FIG. 3  but showing a wall constructed from the panels of  FIG. 6 ,  
         [0017]      FIG. 8  is a view similar to  FIGS. 3 and 7  but showing a wall of a still further embodiment, and  
         [0018]      FIG. 9  is a schematic perspective view of a stud and joist arrangement for multistorey buildings using the wall construction of  FIG. 8 . 
     
    
     DETAILED DESCRIPTION  
       [0019]     As seen in  FIG. 1 , the wall  1  of the first embodiment sits on a foundation  2  which in the first embodiment is a concrete slab  3 . However, the foundation  2  could equally be a timber or metal foundation formed from beams or the like. The wall  1  is fabricated from two like panels  5  and which in  FIG. 1  are indicated as an exterior panel  5 A and an interior panel  5 B. The base of the exterior panel  5 A sits on a Z-shaped shaped galvanised locating strip  7  whilst the base of the interior panel  5 B abuts a lip  8  in the slab  3 .  
         [0020]     At their upper edges, the panels  5 A and  5 B are retained within an E-shaped galvanised cap plate  9 . The cap plate  9  has a centrally located and longitudinally extending groove  10  the dimensions of which define the corresponding dimensions of an interior cavity  12  formed between the two panels  5 A and  5 B. Located in the slab  3  below the cavity  12  is a slot  13  within which, at spaced apart intervals along the length of the wall  1 , a number of threaded rods  15  (only one of which is illustrated) are positioned. The rods  15  are maintained in a vertical orientation by means of a chemical anchor (such as a two part epoxy resin) which surrounds the lower end of each rod  15  and binds it with the slot  13 . The upper end of each of the threaded rods  15  passes through a corresponding hole in the groove  10  and carries a nut  16  which enables the rod  15  to be placed in tension to thereby urge the cap plate  9  against the panels  5  which are thereby placed in compression. A length of sealing tape  18 , which is illustrated in truncated fashion in  FIG. 1 , is used to seal each side edge of the cavity  12 . In this way the air within the cavity  12  remains stagnant and does not move or circulate.  
         [0021]     As seen in  FIG. 2 , each of the panels  5  has an internal surface  21  and an observable surface  22  which may form either the exterior of the wall  1  or the interior of the wall  1 . The internal surface  21  is provided with a series of vertically orientated, longitudinally extending and substantially parallel grooves  24  and ridges  25 . The grooves  24  are substantially semi-circular in configuration whilst the ridges  25  have flat topped crests  26 .  
         [0022]     Illustrated in cutaway fashion in  FIG. 2  is a scalloped sheet of double sided aluminium foil or double sided aluminium coated flim  28  which extends over the entire internal surface  21  and is truncated in  FIG. 2  to reveal the structure of the grooves  24 . The film  28  is provided with flats  29  and curves  30 . The radius of curvature of curves  30  is less than the corresponding radius of curvature of the grooves  24 .  
         [0023]     As best seen in  FIG. 3 , when the two panels  5 A,  5 B are arranged with their internal surfaces  21  facing each other, the gap between the crests  26  is preferably filled by a packing strip  31  of polystyrene, or similar material, which extends along the length of each crest  26  or at least partially therealong. The packing strips  31  may be provided as a single piece as illustrated in  FIG. 3  or as two pieces which abut each other so that both panels  5 A and  5 B are entirely identical. The packing strip  31  preferably provides a measure of resilience, or an ability to absorb shocks arising from horizontal forces applied to the observable surfaces  22 .  
         [0024]     To those skilled in the thermally insulating arts, it will be apparent from  FIG. 3  that a number of sequential thermal barriers are erected. The first thermal barrier is the observable surface  22  and the thickness of the panel  5 A between the observable surface  22  and the base of the groove  24 . The next barrier is the air barrier between the base of the groove  24  and the exterior surface of the film  28 . The next barrier is formed by the interior of the film  28  whilst the next barrier is formed by the air gap between the two films  28 . The next barrier is the interior of the second film  28 . Similarly, the following barrier is the exterior surface of that film  28 . The next barrier is again the air gap between the second film  28  and the base of the groove  24  in the panel  5 B. The final barrier is the thickness between the observable surface  22  of the panel  5 B and the base of the grooves  24 . The sequential barriers result in the accumulation of desirable thermally insulating properties and results in a very high R rating, typically approximately 4 for the construction of  FIGS. 1-3 .  
         [0025]     Turning now to  FIG. 4 , a second embodiment of a wall  100  is illustrated therein. The wall  100  is similar to that of the first embodiment except that the grooves  124  and ridges  125  have a different profile and only a single film  128  coated on each side with aluminium in order to form a reflective thermal barrier. The polystyrene packing strips  131  are essentially as before. The R rating for this embodiment is typically approximately 2.5.  
         [0026]     In a third embodiment illustrated in  FIG. 5 , the wall  199  is formed from two panels as in  FIG. 4  but instead of a single film  128 , four separate film layers  128  are provided with a correspondingly increased number of polystyrene packing slips  131  so that each film  128  is spaced from the others. Thus many layers of stagnant air are created and a correspondingly increased thermal rating R of approximately 7 is the result.  
         [0027]     Turning now to  FIG. 6 , a fourth embodiment of the panel  205  and its method of fabrication will now be described. The panel is formed in a mould  201  which has a rectangular base  202  and two fixed end walls (not illustrated) and two hinged side walls  203  and  204 . The side wall  203  has a protrusion  206  which forms a corresponding groove  207  in one edge of the panel  205 . The side wall  204  has a recess  208  which forms a tongue  209  in the other edge of the panel  205 .  
         [0028]     In order to carry out the moulding procedure, firstly the side walls  203  and  204  are pivoted downwardly about hinges  220  so as to lie in a substantially horizontal position generally flush with the base  202 . Then a planar and rectangular spacer  211  (which preferably takes the form of a fibre cement sheet 6 mm thick) is placed in the mould  201 . The width of the spacer  211  is such that it does not reach quite to the hinges  220 . Over the spacer  211  is laid a thin sheet of aluminium foil  228 . Over the interior of each of the end walls and the side walls  203 ,  204  is located a layer of polyethylene film  219 . Such film is widely used in kitchen applications to cover bowls of salad, etc which are placed in a domestic fridge. The purpose of the film  219  is simply to act as a release agent and ensure that the end walls and side walls  203 ,  204  are maintained clean between individual moulding applications. In particular, the film  219  extends over the hinges  220  so as to maintain same free of liquid cement during the moulding procedure. If the polyethylene film  219  is not used, commercially available spray on release agents can be used instead.  
         [0029]     On top of the aluminium foil  228  is placed a dimpled or castellated sheet  227  fabricated from moulded or pressed paper or cardboard material. Such sheets  227  are widely used in the egg industry as one portion of a two portion container for eggs. Such sheets  227  are inexpensive and provide a convenient means of forming the desired pattern of protrusions and recesses on the interior surface of the panel  205 . Such sheets  227  are also used for pears, apples, tomatoes etc and so a number of such sheets each with a different profile and/or dimensions, are available.  
         [0030]     Once the film  219  and egg carton sheet  227  are in place, the side walls  203  and  204  are swung up into, and latched in, a vertical position in which they are substantially perpendicular to the base  202 . Then lightweight concrete mixture  217  is poured into the mould  201  and on top of the egg carton sheet  227 . Although the egg carton sheet  227  absorbs moisture from the concrete mixture, it is sufficiently strong to maintain the concrete  217  in position until it takes its first set. If desired, the egg carton sheet  227  can be treated by being sprayed with lacquer, varnish or similar to make same to some extent water impervious.  
         [0031]     Once the lightweight concrete  217  has set, the side walls  203  are unlatched and pivoted about the hinges  220 . This enables the solidified slab  205  to be lifted clear of the mould  201 . The aluminium foil  228  comes away with the panel  205  and thus is formed together with the panel  205  and does not need to be added as a subsequent step.  
         [0032]     In  FIG. 7 , a plurality of the panels  205 A and  205 B are placed together to form a wall  200  having an interior cavity  212 . The grooves  207  and tongues  209  are mated so as to form an effective seal between adjacent panels  205 A and adjacent panels  205 B. To either side of the cavity  212  lies a layer of aluminium foil  228 . On the side of each layer of aluminium foil  228  away from the cavity  212 , lies a plurality of enclosed air spaces  235  each of which is formed by the pattern on the egg carton sheet  227 .  
         [0033]     If desired, the observable surfaces  222  of the panels  205 A,  205 B can be covered with a thin layer of lining board  236  (preferably 2.5 mm in thickness) which is glued to the panels  205  and provides a similar external appearance to that of plasterboard for a flush finish. The liner board  236  conveniently conceals the abutting edges of adjacent panels  205 . Preferably to reduce acoustic and thermal transmission through the wall  200 , the abutting edges of adjacent panels  205 A are staggered, or are offset, relative to the abutting edges of adjacent panels  205 B.  
         [0034]     As before, the arrangement of the panels  205 A and  205 B means that there are many interfaces between the opposite observable sides of the wall  200  and thus an extremely high R rating (typically between 5 and 10) for the wall is able to be achieved which results in very low thermal transmission through the wall  200 . The wall  200  also has a good acoustic performance, however, this can be improved by locating (as illustrated in  FIG. 6 ) a layer of fibrous filling  229  (such as that sold under the trade mark TONTINE) between the egg carton sheet  227  and the spacer  211 . Such fibrous filling  229  is compressed between the egg carton sheet  227  and the aluminium foil  228  but remains uncompressed under the spaces and thereby fills the spaces  235 . As a result these voids are filled and therefore the creation of sympathetic vibrations within the voids of the air spaces  235  is avoided. This improves the acoustic performance.  
         [0035]     A still further embodiment is illustrated in  FIG. 8  where the cross-sectional profile of the panel  305  used to form a wall  300  is modified so as to provide longitudinally extending grooves  306  formed at spaced apart intervals across each panel  305 . With the panels  305 A and  305 B arranged to form the wall  300  as illustrated in  FIG. 8 , at various locations along the wall two grooves  306  are positioned in an opposed relationship thereby forming a convenient substantially round slot into which a stud  310  may be located, if desired. In this way, the panels  305  can be used to form a cladding either side of load bearing studs  310  so as to form a wall of substantially increased load bearing ability. The studs  310  are preferably formed from 50 mm diameter round extruded galvanised pipe section.  
         [0036]     In particular, as indicated in  FIG. 9  the studs  310  are spanned by a formed beam  320  created from two L-shaped rolled metal strips which are pop riveted at  325  or otherwise joined together. The formed beam  320  is able to be inexpensively manufactured but has a high bending moment and is therefore sufficiently strong to support the floor joists  330  of an upper floor in a building having two floors or even multiple floors.  
         [0037]     The foregoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention. For example, the aluminium foil or film  28  can be perforated in the region of each crest  26  to allow an adhesive bonding cement to bond between the panels  5 , through the foil or film  28  and on to the packing strip  31 . The foil or film  28  preferably has some “memory” and can therefore be bent during handling but then return to the intended scalloped shape. Similarly, the grooves  24 ,  124  can be of any shape or profile. In addition, in multi-storey buildings, the rods  15  can be dispensed with as the upper floors maintain the panels  5  in compression. It will also be understood that in the drawings the scale of some objects such as the aluminium coated foil  28 ,  128 ,  228  and the film  219  is exaggerated in order to make same visible. Similarly, the masonry can be formed in ways other than by casting lightweight concrete, however, this is the most efficient.  
         [0038]     The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “having” or “including” and not in the exclusive sense of “consisting only of”.