You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to a cladding system, and in particular to a cladding system for mounting stone cladding panels on an exterior of a building to form the facade of the building.  
           [0003]    2. Description of the Prior Art  
           [0004]    It is well known to provide stone cladding systems for buildings, particulary relatively large buildings, office blocks and the like, comprising a plurality of store cladding panels secured to the building structure to form a wall by a mounting means engagable between the building structure and each panel. The cladding panels thus form the facade of the building. A known mounting means comprises an anchoring system which requires a brick or concrete wall to which mechanical anchors for each cladding panel are attached or embedded. The anchors fix the stone cladding panels in two load points at a bottom of each stone cladding panel and two restraint points at a top of the stone cladding panel. With this system, if the cladding panels need to be removed for replacement or access, for example, it is usually very difficult to do so and typically the mechanical anchors are damaged in the process. Further the stone cladding panels have to be installed in a desired sequence, usually building up from the base of the building and the panels have to be checked frequently to ensure they are plumb and level. As can be appreciated, this is somewhat tedious and time consuming. A further disadvantage of the sequential construction methods is that if during construction the next required cladding panels are not immediately available on site, the construction of the facade comes to a halt with consequent construction delays and added cost.  
           [0005]    The present invention is directed towards overcoming these problems.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the invention there is provided a stone cladding system, including:  
           [0007]    a plurality of stone cladding panels secured to a building structure to form a wall by mounting means engagable between the building structure and each panel,  
           [0008]    mounting means for each cladding panel comprising a pair of cladding panel support rails, namely an upper rail and a lower rail,  
           [0009]    means for mounting said rails in a substantially horizontal orientation and vertically spaced-apart on the building structure,  
           [0010]    a bottom of the cladding panel engaging and seating on the lower rail and one or more retaining clips for releasably securing the top of the cladding panel to the upper rail,  
           [0011]    each retaining clip having an inner end and an outer end, said inner end of the clip being adapted for snap engagement with the upper rail, and said outer end of the clip having a retaining arm engagable within a slot extending along a top edge of the cladding panel.  
           [0012]    Advantageously, in the cladding system of the present invention, each cladding panel is independently demountably secured between a pair of support rails. The cladding panel can be readily, easily and quickly mounted on or removed from the support rails. This system also provides great flexibility in construction. The cladding panels can be mounted on the rails independently and out of any particular sequence so that there are no construction delays providing that there are some cladding panels available which can be mounted in any order on the rails. A further advantage is that the cladding panels can be mounted on the rails from the top of the building downwardly to the base of the building. This means that scaffolding required for are completed moving downwardly from the top, thus providing a cost saving as the scaffolding is usually hired as needed for use on a building site.  
           [0013]    In a particularly preferred embodiment, the bottom of each cladding panel is supported along substantially all of its length up the lower rail. This provides good support for the cladding panel. Also, providing it is ensured that the lower rail is horizontal, all the cladding panels in a row can be dropped onto the rail and they will be level. This facilitates speedy construction.  
           [0014]    In a preferred embodiment, the rails are mounted upon a plurality of spaced-apart vertical mullions having associated anchor means for supporting each mullion in an upright orientation on the building structure. Thus conveniently, once the mullions are in place, the cladding panel support rails may be mounted on the mullions with any desired spacing between each row of rails. Further, in many cases, it will be possible to mount the mullions directly to the floors of the building structure which may mean it is not necessary to build a brick or block wall between the floors, again providing a saving in both time and cost.  
           [0015]    While in some cases, it may be possible to mount the mullions directly to the support structure by means of an anchor bolt, for ex(ample, it is preferred that an anchor bracket is provided which conveniently may be L-shaped having a wall fixing plate which can be secured to the building structure by means of a bolt or the like and an outwardly extending mullion support plate which can be secured to the mullion in any suitable fashion such as by means of a locking bolt secured between the anchor bracket and the mullion.  
           [0016]    Conveniently, complementary interengagable formations are provided upon associated mating faces of each anchor bracket and mullion. This advantageously provides resistance to wind shear. Preferably, the complementary interengagable formations comprise mating serrations on the mullion and on the anchor bracket. Ideally, the serrations have ridges arranged in a vertical orientation.  
           [0017]    In a further embodiment, each mullion has two mutually perpendicular side faces of panel from the building structure is provided. Each mullion is preferably of rectangular box section material.  
           [0018]    In a further embodiment, a reentrant slot is provided along a face of the mullion for reception of a mounting bolt having a head and a shank, the head being slidably captured within the slot with the shank projecting outwardly of the slot for attachment to the mounting support for the mullion. This conveniently provides for ease of securing the mullions on the mounting support such as the anchor bracket as the mounting bolt can be slid along the slot for alignment with the anchcor bracket. Typically, the anchor bracket has a slot for reception of the mounting bolt which may be open-ended to facilitate engagement of the bolt in the slot  
           [0019]    In another embodiment, the lower rail has an outwardly projecting panel support arm with an upturned flange at an outer end of the arm which is engagable within a mounting slot extending along a bottom edge of the panel. Thus, the bottom of each panel is securely retained on the lower rail.  
           [0020]    In a further embodiment, the retaining means comprises a panel retaining clip, an outer end of the clip having a retaining flap engagable within a slot extending along a top edge of the panel, and an inner end of the clip being adapted for snap engagement with the upper rail. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:  
         [0022]    [0022]FIG. 1 is a detail partially cut-away perspective view of a cladding system according to the invention;  
         [0023]    [0023]FIG. 2 is an end elevational view of a mullion forming portion of the cladding system;  
         [0024]    [0024]FIG. 3 is an end elevational view of an anchor bracket forming portion of the cladding system;  
         [0025]    [0025]FIG. 4 is an end elevational view of an intermediate cladding panel support rail forming portion of the cladding system;  
         [0026]    [0026]FIG. 5 is a cladding panel retaining clip forming portion of the cladding system;  
         [0027]    [0027]FIG. 6 is an end elevational view of a bottom cladding panel support rail of the cladding system;  
         [0028]    [0028]FIG. 7 is an end elevational view of a top cladding panel support rail of the cladding system;  
         [0029]    [0029]FIG. 8 is an end elevational view of another panel retaining clip of the cladding system;  
         [0030]    [0030]FIG. 9 is a detail plan view showing the cladding system in use;  
         [0031]    [0031]FIG. 10 is a view similar to FIG. 9 showing the cladding system in an alternative position of use;  
         [0032]    [0032]FIG. 11 is a detail partially sectioned elevational view showing portion of the cladding system, in use;  
         [0033]    [0033]FIG. 12 is a detail partially sectioned elevational view showing portion of the cladding system, in use;  
         [0034]    [0034]FIG. 13 is a view similar to FIG. 12 showing an alternative arrangement of the cladding system;  
         [0035]    [0035]FIG. 14 is an elevational view showing a portion of a stone cladding facade of the invention;  
         [0036]    [0036]FIG. 15 is an elevational view of a cladding support frame of the invention;  
         [0037]    [0037]FIG. 16 is an end elevational view showing the cladding support frame mounted on a building;  
         [0038]    [0038]FIG. 17 is an elevational view of a mullion splice forming portion of the system;  
         [0039]    [0039]FIG. 18 is a sectional plan view illustrating the mullion splice in use;  
         [0040]    [0040]FIG. 19 is a detail perspective view showing a portion of another cladding system according to the invention;  
         [0041]    [0041]FIG. 20 is a detail exploded perspective view of the cladding system portion shown in FIG. 19;  
         [0042]    [0042]FIG. 21 is a sectional view of a mullion of the cladding system of FIG. 19; and  
         [0043]    [0043]FIG. 22 is a sectional view of the cladding system of FIG. 19. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]    Referring to the drawings, there is illustrated a cladding system according to the invention, indicated generally by the reference numeral  1 . The cladding system  1  comprises a plurality of upright mullions  2  secured to an outside of a building by means of anchor brackets  3 , shown in FIG. 1 secured to a floor  4  of the building by means of an anchor bolt  5 . The mullions  2  are mounted at spaced intervals along an exterior of the building as best seen in FIG. 15. A number of horizontal cladding panel support rails  6  are mounted on the mullions  2  forming vertically spaced-apart rows of cladding panel support rails  6 . Stone cladding panels  8  are mounted between each pair of vertically adjacent rows of panel support rails  6 . A bottom of the cladding panel  8  seats on a lowermost rail  6  and a top of the cladding panel  8  is secured to the associated uppermost rail  6  by means of retaining clips  9 . Typically, two retaining clips  9  are provided for each panel  8 . The mullions  2 , anchor brackets  3  and rails  6  they are assembled to form a mounting grid on a face of the building on which cladding panels  8  can be releasably mounted.  
         [0045]    Referring in particular to FIG. 2, each mullion  2  is generally of box section extruded aluminium having serrations  10  along two mutually perpendicular adjacent walls of different widths, forming a wide anchor wall  11  and a narrow anchor wall  12 . The remaining walls form a wide rail support wall  14  and a narrow rail support wall  15 , each wall  14 ,  15  having a flat outer face. Depending on the orientation of the mullion  2  relative to the exterior of the building as shown in FIGS. 9 and 10, the spacing of the rails  6  and hence the spacing of the cladding panels  8  from the exterior of the building can be adjusted between a normal configuration shown in FIG. 9 with a wide cavity between the building and the cladding panels  8  and a narrow construction, as shown in FIG. 10 in which the mullion  2  is turned through 90°, with a narrow cavity between the cladding panels  8  and the building.  
         [0046]    Reentrant slots  16  are provided along each of the serrated anchor walls  11 ,  12  of the mullion  2  for reception of a mounting bolt  17  (see FIG. 9) having a head  18  and a shank  19 , the head  18  being slidably captured within the slot  16  with the shank  19  projecting outwardly of the slot for attachment of the mullion  2  to the anchor bracket  3 .  
         [0047]    Referring particularly to FIGS. 1, 3 and  11 , the anchor bracket  3  is of aluminium material and is L-shaped having an inner anchor plate  20  for attachment to the floor  4  or wall of the building. The anchor plate  20  has a through hole for reception of an anchor bolt  5  which secures the anchor bracket  3  to the floor  4  or wall of the building. Extending perpendicularly outwardly at one end of the anchor plate  20  in a mullion support plate  22 , one face of which is provided with serrations  10  corresponding to the serrations  10  on the mullion  2 . An open-ended mounting bolt receiving slot  24  extends inwardly from an outer edge of the mullion support plate  22 . This elongate slot  24  allows for construction tolerances in the building structure when fixing the mullions in a vertical orientation. When the mullion  2  is engaged with the anchor bracket  3 , the serrations  10  on the mullion  2  and anchor bracket  3  interengage and the mounting bolt  17  is slid along the slot  16  on the mullion  2  and is engaged with the slot  24  in the anchor bracket  3  and is secured thereto by means of a lock nu: 25 .  
         [0048]    Additional self-drilling, self-tapping dead load screws  27  can be installed, as required, through the mullion support plate  22  of the anchor bracket  3  and into the mating serrated side wall  11 ,  12  of the mullion  2  to resist gravity load of the stone and aluminium. It will be noted that the serrations  10  are arranged in a vertical orientation to give a firm engagement between the mullions  2  and anchor brackets  3  which provide positive resistance against wind load without introducing shear on the mounting bolts.  
         [0049]    Referring in particular to FIG. 4, each rail  6  has a generally box-section extruded aluminium body  29 . An inner wall  30  of the body  29  is extended outwardly to form flanges  31  for attachment of the rail  6  to the mullions  2  by means of Elco Drilflexself tapping screws  47  with Stalguard coating. A lower wall  32  of the body  30  is extended outwardly to form a panel support arm  33  having an upturned flange  34  at an outer end of the arm  33  for engagement within an associated kerf or mounting slot  35  (FIGS. 1 and 12) which extends continuously along a bottom edge of the cladding panel  8 . Extending outwardly from the flange  31  beneath the body  29  is a strip  36  which defines, with an underside of the body  30 , a receiver  37  for snap engagement with the panel retaining clips  9 .  
         [0050]    Referring in particular to FIG. 5, the panel retaining clip  9  is generally L-shaped in section having a cranked horizontal top plate  38 , an inner end of which terminates in a head  39  for snap engagement in the receiver  37 , the head  39  having a shoulder  40  which catches behind a complementary shoulder  41  of the receiver  37 . At an outer end of the plate  38  is a downwardly extending arm  42  which locates within an associated kerf or slot  43  extending continuously along a top edge of the cladding panel  8 . A hooked lip  44  at an outer end of the top plate  38  engages within a complementary slot  45  in a front face of the flange  34  to retain an outer portion of the top plate  38  against an underside of the arm  33  when the clip  9  is engaged with the receiver  37  as can be seen in FIG. 12.  
         [0051]    [0051]FIG. 6 shows an arrangement of the cladding panel support rail, in this case denoted  6   a  for mounting at a bottom of a stack of cladding panels  8 . This does not have means for engagement with a mounting clip  9  as it simply supports the lowermost  
         [0052]    [0052]FIG. 7 shows another arrangement of the cladding panel support rail, denoted  6   b,  for mounting at a top of a stack of cladding panels  8 . A receiver  37  for reception of the retaining clip is provided in this case at a top of the body  29  and an associated top retaining clip  9   a  is provided for engagement with the receiver  37 .  
         [0053]    Referring in particular to FIG. 9, one arrangement of the mounting of a mullion  2  by means of the anchor bracket  3  on a floor  4  of the building is shown. An insulation panel  50  can conveniently be retained behind the mullion  2 . In this case, the wide anchor wall  11  engages the anchor bracket  3 .  
         [0054]    [0054]FIG. 10 shows an alternative mounting arrangement for the mullion  2  where it is desired to provide a reduced cavity between the building and the cladding panels  8 . In this case, the narrow anchor wall  12  engages the anchor bracket  3 .  
         [0055]    [0055]FIG. 11 shows an elevational view illustrating the mounting of a mullion  2  on the anchor bracket  3 .  
         [0056]    [0056]FIG. 12 shows the arrangement for securing the rail  6  on a mullion  2  with the seating of a cladding panel  8  on the rail  6  and the engagement of a retaining clip  9  with an underside of the rail  6  to secure an upper end of a lower panel  8  to the rail  6 .  
         [0057]    [0057]FIG. 13 shows an alternative arrangement of retaining clip  49  for securing a top of a lower panel  8  to an underside of the rail  6 . In this case also, it will be noted that the inner faces of the slots  35 ,  43  are rebated.  
         [0058]    Referring to FIG. 14, there is shown one possible arrangement of stone cladding panels  8 .  
         [0059]    [0059]FIG. 15 shows the arrangement of the mullions  2 , anchor brackets  3  and rails  6  which essentially form a modular aluminium grid or frame on an exterior of the building on which the stone cladding panels  8  are releasably mounted. being secured to floors  4  of the building with the mullions  2  mounted therebetween. Where an intermediate wall  55  is provided between floors  4  of the building, an additional wind load anchor  56  may be provided between the mullions  2  and the wall  55 . This can be similar to the anchor bracket  3  previously described. A number of mullions  2  can be joined end to end by means of fish plates  57  or other type of splicing bracket to form a continuous mullion  2  between a top and a bottom of the building.  
         [0060]    Referring to FIGS. 17 and 18, there is shown a mullion splice  60  for interconnecting a pair of vertically aligned mullions  2  end to end. The mullion splice  60  is of channel section for reception of a bottom end  61  of an upper mullion  2  and for reception of an upper end  62  of a lower mullion  2 . The mullion splice  60  is fixed to the lower mullion  2  by means of a self-tapping screw  64  which engages through a hole  65  in the mullion splice  60  with the mullion  2 . The upper mullion  2  is free to move vertically within the upper pocket  61  to accommodate thermal expansion and contraction of the mullions  2 .  
         [0061]    Referring now to FIGS.  19  to  22  there is shown another cladding system according to a further embodiment of the invention indicated generally by the reference numeral  70 . Parts similar to those described previously are assigned the same reference numerals. In this case there is shown an alternative construction of a mullion  72  and associated L-shaped anchor bracket  73  for securing the mullion  72  to a floor  4  of a building by means of an associated anchor bolt  75 . The anchor bolt  75  in this case engages within an associated elongate mounting slot  76  provided at an outer face of the floor  4 . Optionally a drilled expansion anchor arrangement as described previously could alternatively be used. However it will be appreciated that the elongate slot  76  facilitates correct positioning of the anchor bracket  73  and associated mullion  72 .  
         [0062]    At an inner end of each mullion  72  at each side of the mullion  72  there is provided a re-entrant slot  80  within which is slideably received a complementary mullion nut bar  81 . An associated anchor nut bar  82  co-operates with the anchor bracket  73  which is clamped between the nut bars  81 ,  82  by a lock nut  83  which engages with associated bar  81  is threaded for engagement by the lock nut  83  when a shank of the lock nut  83  passes through the hole  85  in the anchor nut bar  82  and the open ended slot  24  in the anchor bracket  73 . It will be noted that the anchor nut bar  82  has a serrated engagement face  86  for complementary engagement with a serrated engagement face  87  on the anchor bracket  73 . Fastening screws  88  are engageable through associated holes  89  in the mullion nut bar  81  with an inner wall of the slot  80  for locking the mullion nut bar  81  at any desired position on the mullion  72 .  
         [0063]    Each mullion  72  has a pair of fins  90  which project outwardly at opposite sides of the mullion  72 . These fins  90  are mounted intermediate a front outer end  93  and a rear inner end  94  of the mullion  72  and extend between a top and a bottom of the mullion  72 . Ribs  96  project outwardly of each side  97 ,  98  of the mullion  72  spaced-apart from each fin  90 , forwardly of the fin  90 , to define with an inner end of the fin  90  a seal retaining channel  99  on the mullion  72 .  
         [0064]    [0064]FIG. 22 shows the mullion  72  in use wherein the fins  90  support insulation panels  100 . Ends of the insulation panels  100  are secured to the fins  90  by self-tapping screws  102 . Weather seals  104  are provided along the channels  99  and also along an outer edge of each insulation panel  100 , between the insulation  100  and the side walls  97 ,  98  of the mullion  72 .  
         [0065]    It will be appreciated that the fins  90  on the mullions  72  facilitate the integration of insulation and water seals with the stone cladding support system. This is particularly advantageous from a construction point of view in providing a rain screen insulation and stone system all in one.  
         [0066]    In use, the anchor bracket  73  is positioned at the correct location along the slot  76  and secured in position by the anchor bolt  75  which engages a halfen insert (not shown). Next the mullion  72  is positioned at the correct in/out location using the nut bars  81 ,  82  and associated lock nut  83 , the serrations on the anchor nut bar  82  and anchor bracket  73  giving the correct in/out location. The mullion  72  can be positioned at the correct elevation by sliding it up and down on the mullion nut bar  81  and when at the correct elevation the fasteners  88  are engaged through the mullion nut bar  81  with the then be mounted between the mullions. Rails are attached to the mullions  72  and cladding panels  8  mounted on the rails as previously described.  
         [0067]    It will be noted that each stone cladding panel is independently fixed on the support frame formed by the rails and mullions. Also, each stone cladding panel is supported continuously along a bottom of the cladding panel to provide an even load distribution. In many cases, no brick or block wall is required to support the frame formed by the mullions and rails. The system according to the invention provides great flexibility in that the stone cladding panels can be mounted on the rails in any order. Damaged or defective stone cladding panels can be easily replaced.  
         [0068]    The invention is riot limited to the embodiments hereinbefore described which may be varied in both construction and detail within the scope of the appended claims.

Summary:
A stone cladding system for building has a support frame formed by a plurality spaced-apart upright mullions fixed to an exterior of a building by anchcor bracke with a number of horizontal cladding panel support rails mounted in vertically space apart rows on the mullions. Each stone cladding panel is mounted between adjacent pair of vertically spaced-apart rails with a bottom of the cladding pa seated on the lowermost rail and a top of the cladding panel secured to the uppermo rail by a pair of retaining clips. A bottom of each stone cladding panel is fu supported along its length by the lowermost rail.