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CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part application of U.S. patent application Ser. No. 11/336,242 filed on Jan. 20, 2006 which claims the benefit of Provisional Patent Application Ser. No. 60/645,101 filed Jan. 20, 2005 and Provisional Patent Application Ser. No. 60/655,370 filed Feb. 23, 2005, which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to wall panel joints and systems for wall panel application. 
       BACKGROUND INFORMATION 
       [0003]    Architectural panel has been in use for many years. All architectural panel systems can be classified into two major categories, namely, “face-sealed” and “vented rainscreen” systems. 
         [0004]    Face-sealed systems include all systems with joinery that make use of sealant in the joinery whereby the system is substantially impermeable to either water or air. Achieving complete face seal is the very basis of all face seal systems. Sealant can be caulking, gasket, or another sealant of similar function. However, the lack of permeability/venting to either water vapor or air makes this system problematic. 
         [0005]    On the contrary, vented rainscreen systems are designed to allow for permeability through the joinery, known as vents. The vents allow for breathability and rapid pressure equalization within the system cavity. However, these systems allow water to penetrate, causing water damage which is also problematic. 
         [0006]    Unfortunately, there are deficiencies in conventional wall panel systems that lead to water damage and/or lack of venting capability. Furthermore, the systems have numerous distinct components that are required to build the conventional wall panel systems. 
       SUMMARY 
       [0007]    In contrast to the above-described wall panel systems, the instant system has a symmetric panel structure with a wall panel joint having a pair of perimeter clips and at least two filler strips defining at least one chamber in addition to a wall cavity. The chamber provides for pressure equalization by increasing the air pressure within the chamber until it equals the applied wind pressure. Furthermore, the configuration of the flange portion of the outer strip flange projecting higher like the mounting flange results in blocking water. When the pressures are equal, water cannot enter the chamber. This state is attained quickly. Thus, the wall panel joints allow the wall panel system to attain optimal ventilation within the system, but prevent and minimize water entry. Furthermore, the system in addition to the pressure equalization chamber provides an internal gutter system and allows for thermal movement between adjacent wall panel units. 
         [0008]    One embodiment is directed to a wall panel system which includes a plurality of wall panel units. Each wall panel unit has a wall panel and a plurality of perimeter clips. Each wall panel has a planar surface and a plurality of mounting flanges. The mounting flanges are generally perpendicular to the planar surface. 
         [0009]    Each perimeter clip includes a body and a panel flange extending from the body. The panel flange is adapted to engage with one of the mounting flanges of one of the wall panels. The perimeter clips have at least a pair of strip flanges extending from the body. The strip flanges and the body define at least a pair of pockets. An attachment clip engages a pair of the perimeter clips for retaining the perimeter clips and the associated wall panel of the wall panel unit. 
         [0010]    A pair of filler strips is associated with a pair of perimeter clips of the plurality of perimeter clips. The filler strips with the pair of perimeter clips define a wall panel joint. Each of the filler strips has a pair of receiving edges. Each of the filler strips extends between adjacent perimeter clips with a first receiving edge received in a pocket of one of the perimeter clips and the second receiving edge received in a pocket of the other perimeter clip. The pair of filler strips defines a chamber interposed between the adjacent perimeter clips and the filler strip for allowing pressure equalization while minimizing water entry into the wall cavity. 
         [0011]    In some arrangements, the mounting flanges of each wall panel are four mounting flanges including a top horizontal mounting flange, a bottom horizontal mounting flange, and a pair of vertical mounting flanges. Each perimeter clip is identical and mountable on vertical mounting flanges and horizontal mounting flanges. 
         [0012]    In an embodiment, each perimeter clip is identical and the adjacent pair of perimeter clips, the pair of perimeter clips, with the filler strips define the wall panel joint. The perimeter clips are positioned mirrored to each other such that the pockets align with each other. 
         [0013]    In an embodiment, the wall panel system for securing to a wall of a building includes at least one wall securing device secured to the wall of the building. The attachment clip is carried by the at least one wall securing device wherein the wall panel units and the wall of the building define a wall cavity having a pressure equal to the outside atmosphere while not infiltrated by rain. 
         [0014]    In an embodiment, the pair of strip flanges includes an outer strip flange, a middle strip flange, and an inner strip flange projecting from the body of the perimeter clip. The outer strip flange defines an “U” shaped outer pocket of the pockets. The middle strip flange and the inner strip flange define an “U” shaped inner pocket of the at least a pair of pockets. 
         [0015]    In some arrangements, a middle strip flange is interposed between the outer strip flange and the inner strip flange. The inner strip flange has varying thickness including a main portion and a thinner projection portion that extends from the main portion away from the body of the perimeter clip. A protrusion of the inner strip flange projects from the body and the main portion projects away from the thinner projection portion. 
         [0016]    In some arrangements, each perimeter clip is identical and the adjacent perimeter clips are positioned mirrored to each other such that the “U” shaped inner pockets align with each other. The pair of filler strips includes an inner filler strip that is received by and extends between the “U” shaped inner pockets of the adjacent perimeter clips. The thinner projection portion and the inner filler strip define an arm receiving space for receiving an upper arm portion of the at least one attachment clip. 
         [0017]    In an embodiment, the attachment clip has a pair of grooves for accepting the inner strip flange of one of the perimeter clips wherein one of the perimeter clips is for holding and supporting the weight of the perimeter clip and the wall panel of the wall panel unit. The upper arm portion of the attachment clip is received in the arm receiving space interposed between the filler strip and thinner projection of the flange for limiting motion of the perimeter clip in a direction perpendicular to the planar portion of the wall panel. 
         [0018]    In an embodiment, the adjacent mounting flanges of the adjacent wall panel and the outer filler strip define a gutter channel for channeling water. 
         [0019]    In an embodiment, each perimeter clip is identical and mountable on vertical mounting flanges and horizontal mounting flanges of the wall panels. The adjacent pair of perimeter clips with the filler strips defining the wall panel joint, are positioned mirrored to each other such that the pockets align with each other. The outer flange has a tip flange portion that extends further towards the other wall panel of the wall panel joint than the respective mounting flange such that any water entering the outer pocket will drain over the mounting flange rather than enter the chamber. 
         [0020]    In an embodiment, the perimeter clip has at least three strip flanges and at least three pockets defined by the at least three strip flanges and the body. There are at least three filler strips. Each of the filler strips has a pair of receiving edges. Each of the filler strips extends between adjacent perimeter clips with a first receiving edge received in a pocket of one of the perimeter clips and the second receiving edge received in a pocket of the other perimeter clip. There are at least two chambers wherein each chamber is interposed between the adjacent perimeter clips and a pair of the at least three filler strips for allowing pressure equalization while minimizing water entry. 
         [0021]    In an arrangement, the at least one pair of strip flanges extending from the body includes an outer strip flange, a middle strip flange, and an inner strip flange. The outer strip flange defines a “U” shaped outer pocket. The middle strip flange and the inner strip flange define a “U” shaped inner pocket. The pair of filler strips includes an outer filler strip extending between the “U” shaped outer pocket of an adjacent perimeter clip and an inner filler strip extending between the “U” shaped inner pocket of the adjacent perimeter clip. The outer filler strip and the inner filler strip define a chamber interposed between the adjacent perimeter clips and the filler strip for allowing pressure equalization while minimizing water entry. 
         [0022]    In an arrangement, the wall panel system is secured to a building having a wall structure. The plurality of wall panel units includes at least four wall panel units. Each wall panel has four mounting flanges including a top horizontal mounting flange, a bottom horizontal mounting flange, and a pair of vertical mounting flanges. Each perimeter clip is identical and mountable on vertical mounting flanges and horizontal mounting flanges. The adjacent perimeter clips are positioned mirrored to each other such that the pockets align with each other. A wall securing device is associated with a corner of each of the plurality of wall panel units and is secured to the wall structure of the building. An attachment clip is carried by each of the wall securing devices wherein the wall panel units and the wall of the building define a wall cavity having a pressure equal to the outside atmosphere while not infiltrated by rain. 
         [0023]    In an embodiment, a wall panel joint includes a pair of perimeter clips and a pair of filler strips. Each perimeter clip includes a body, a panel flange extending from the body, and at least a pair of strip flanges. The panel flange is adapted to engage with one of the mounting flanges of one of the wall panels. The strip flanges and the body define at least a pair of pockets. Each of the filler strips has a pair of receiving edges. Each of the filler strips extends between adjacent perimeter clips with a first receiving edge received in a pocket of one of the perimeter clips and the second receiving edge received in a pocket of the other perimeter clip. The pair of filler strips defines a chamber interposed between the adjacent perimeter clips and the filler strips for allowing pressure equalization while minimizing water entry. 
         [0024]    In one embodiment, a method of installing a wall panel system includes providing a plurality of wall panel units. Each unit has a wall panel and four perimeter clips. Each wall panel has a planar surface and four mounting flanges. The mounting flanges are generally perpendicular to the planar surface. 
         [0025]    A plurality of wall securing devices are mounted to the wall structure of the building. The wall securing devices are positioned on the wall structure such that there is at least one wall securing device associated with each corner of each of the plurality of wall panel units. A plurality of attachment clips are mounted to the perimeter clip associated with the top horizontal mounting flange of the wall panel of at least one of the wall panel units by securing a pair of grooves on the attachment clip around an inner strip flange of the at least a pair of strip flanges of the perimeter clip. A plurality of attachment clips are mounted to the wall securing device located in proximity to where the bottom horizontal mounting flange of the wall panel of at least one of the wall panel units is to be located. The perimeter clip of the bottom horizontal mounting flange of the wall panel of at least one of the wall panel units is positioned such that the plurality of attachment clips mounted to the wall securing device have an upper arm portion located in an arm receiving space defined by the inner strip flange of the perimeter clip and a filler strip. 
         [0026]    The plurality of attachment clips are secured to the perimeter clip associated with the top horizontal mounting flange of the wall panel of at least one of the plurality of the wall panel units to the associated plurality of wall securing devices mounted to the wall structure of the building. 
         [0027]    A pair of filler strips is positioned with at least one of the perimeter clips of at least one of the wall panel units. The steps of mounting of a plurality of wall securing devices, mounting a plurality of attachment clips, positioning the perimeter clip and the securing the plurality of attachment clips are repeated until the wall panel system is completely secured to the building with a wall panel joint that has at least one chamber interposed between the adjacent perimeter clips and the filler strips allowing pressure equalization while minimizing water entry. 
         [0028]    These aspects of the invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the appended claims and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0029]    These and other features and aspects of the present invention will be better understood by reading the following detailed description of preferred embodiments, taken together with the drawings wherein: 
           [0030]      FIG. 1  is a break-away front view of a single chamber in addition to a wall cavity embodiment of a wall panel system of the present invention; 
           [0031]      FIG. 2  is a horizontal sectional view showing a vertical joint of the single chamber embodiment of  FIG. 1  of the present invention; 
           [0032]      FIG. 3  is a sectional view of one embodiment of a horizontal joint of the single chamber embodiment of  FIG. 1  of the present invention; 
           [0033]      FIG. 4A  is a front view showing the relationship of adjacent wall panel units; 
           [0034]      FIG. 4B  is an enlarged section of four adjacent wall panel units taken along the area  4 B in  FIG. 4A ; 
           [0035]      FIG. 5  is an illustration of the flow of air through the vertical joint according to one embodiment of the present invention; 
           [0036]      FIG. 6  is a sectional view of a vertical joint of an alternative single chamber embodiment; 
           [0037]      FIG. 7  is a sectional view of one embodiment of a double chamber vertical joint embodiment of the present invention; and 
           [0038]      FIG. 8  is a sectional view of one embodiment of the double chamber horizontal joint embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0039]    A wall panel system that has a symmetric panel structure with a wall panel joint having a pair of perimeter clips and at least two filler strips defining at least one chamber in addition to a wall cavity. The chamber provides for pressure equalization by increasing the air pressure within the chamber until it equals the applied wind pressure. When the pressures are equal, water cannot enter the chamber. This state is attained quickly. Furthermore, the configuration of the flange portion of the outer strip flange projecting higher like the mounting flange results in blocking water. Thus, the wall panel joints allow the wall panel system to attain optimal ventilation within the system, but prevent and minimize water entry. Furthermore, the system, in addition to the pressure equalization chamber, provides an internal gutter system and allows for thermal movement between adjacent wall panel units. 
         [0040]    Referring to  FIG. 1 , a portion of a wall panel system  20  is shown. The wall panel system  20  has a plurality of wall panel units  22 . Each wall panel unit  22  includes a wall panel  24  and a plurality of perimeter clips  26 . In addition, the wall panel system  20  includes a plurality of filler strips  28  and at least one attachment clip  30  and a wall securing device  32 . 
         [0041]    Still referring  FIG. 1 , each wall panel  24  has a planar portion  34  and plurality of mounting flanges  36 . In a preferred embodiment, there is a perimeter clip  26  associated with each of the mounting flanges  36  of the wall panel  24 . Each wall panel unit  22  consists of a wall panel  24  and the four associated perimeter clips  26 . In the preferred embodiment, the perimeter clips  26  are mitered and engage each other at the corners of the wall panel  24 . 
         [0042]    Still referring to  FIG. 1 , portions of four wall panel units  22  are shown. Each wall panel unit  22  typically interacts with four adjoining wall panel units  22  and in addition is diagonally adjacent to four additional wall panel units  22 . Adjoining wall panel units  22  have parallel mounting flanges  36  wherein the adjoining perimeter clips  26  and the filler strips  28  form a wall panel joint  40 . In  FIG. 1 , the wall panel unit  22   a  is adjoining wall panel units  22   b  and  22   c  with filler strips  28  extending between the units  22  respective perimeter clips  26  as explained in greater detail below. Wall panel unit  22   d  is adjacent to wall panel  22   a.    
         [0043]    In one embodiment, the wall panels  24  are made of an aluminum composite material (ACM) that has two sheets of prefinished 0.020″ aluminum (85% recycled content) bonded to a low-density polyethylene core. The perimeter clips  26  are extruded and made of aluminum alloy such as 6061 aluminum. The filler strips  28  are made of either ACM or a contrasting material. The attachment clip  30  and the wall securing device  32  are made of aluminum alloy. It is recognized that other metals and materials can be used including zinc, copper, stainless steel, and titanium. 
         [0044]    Referring to  FIG. 2 , a horizontal sectional view of the wall panel system  20  is shown. The wall panel joint  40  of two adjoining wall panel units  22  is shown. The wall panel  24  has the planar portion  34  and a mounting flange  36 . The two perimeter clips  26  shown are identical. Each perimeter clip  26  has a body  42  and a panel flange  44  which extends from the body  42 . The panel flange  44  forms a right angle to engage the planer portion  34  and the mounting flange  36  of the wall panel  24 . The panel flange  44  can be attached in many ways to the wall panel  24  including by rivets  46  as shown in  FIG. 2 . It is recognized, however that other methods including adhesives and spot welding can be used to secure the panel flange of the perimeter clip  26  to the wall panel  24 . 
         [0045]    In addition, the perimeter clip  26  has an outer strip flange  48 . The outer strip flange  48  forms a “U” shaped outer pocket  50 . The perimeter clip  26  also has a middle strip flange  52  and an inner strip flange  54 . The middle strip flange  52  and the inner strip flange  54  form a “U” shaped inner pocket  56 . 
         [0046]    Still referring to  FIG. 2 , the filler strips  26  include an inner filler strip  58  and an outer filler strip  60 . In the embodiment shown, the inner filler strip  58  and the outer filler strip  60  are identical in material but have different widths. The different widths assist in forming an internal gutter. The filler strips  60  and  58  each have a pair of receiving edges  62 . The receiving edges  62  of the filler strips  60  and  58  are received by the “U” shaped pockets  50  and  56  to span between the perimeter clips  26  of adjacent wall panel units  22 . The filler strips  28 , the inner filler strip  58  and the outer filler strip  60 , in conjunction with the associated perimeter clips  26  define a chamber  64 . The chamber or pocket  64  is designed for ventilation and thermal movement. This chamber  64  allows for pressure equalization and permeability through impermeable material as explained further with respect to  FIG. 5 . The adjacent perimeter clips  26 , the inner filler strip  58 , and the outer filler strip  60  form a wall panel joint  40 . 
         [0047]    Still referring to  FIG. 2 , the outer strip flange  48  and the middle strip flange  52  each have a tip flange portion  68  that projects into the chamber  64  from the remainder of the flange at an angle α and β respectively. The angles range from between 10 degrees and 60 degrees and assist in positioning the filler strips  28  during installation of the wall panel system  20  on a building. In the embodiment shown, angle α is set at approximately 15° and β is approximately 60°. The dash lines represent edges of the perimeter clip  26  and the wall panel  24  spaced from the section. 
         [0048]    The wall joint  40  includes the pair of perimeter clips  26  and the filler strips  28 . The perimeter clips  26 , while identical, have one of the adjoining or adjacent clips  26  flipped such that the perimeter clips  26  mirror each other. The wall joint  40  is symmetrical about an axis that is perpendicular to the filler strips  28 ; the axis extends up and down in  FIG. 2 . 
         [0049]    Referring to  FIG. 3 , a vertical section of the wall panel system  20  is shown. As indicated above, each wall panel unit  22  in the embodiment shown has four perimeter clips  26 . While  FIG. 3  show different perimeter clips  26  than those shown in  FIG. 2  in that these perimeter clips run horizontally in contrast to vertically, the perimeter clips  26  are identical in configuration. The person assembling the wall panel units  22  does not need to stock two styles of the perimeter clip. 
         [0050]    The perimeter clips  26  have the panel flange  44  for securing to the wall panel  24 . The panel flange  44  forms a right angle to engage the planer portion  34  and the mounting flange  36  of the wall panel  24 . The perimeter clip  26  has the outer strip flange  48  to form the “U” shaped outer pocket  50 . The middle strip flange  52  and an inner strip flange  54  of the perimeter clip  26  form the “U” shaped inner pocket  56 . 
         [0051]    Still referring to  FIG. 3 , the receiving edges  62  of the filler strips  58  and  60  are received by the “U” shaped pockets  50  and  56  to span between the perimeter clips  26  of adjacent wall panel units  22 . The filler strips  28 , the inner filler strip  58  and the outer filler strip  60 , in conjunction with the associated perimeter clips  26  define the chamber  64 . 
         [0052]    Still referring to  FIG. 3 , the inner strip flange  54  of the perimeter clip  26  has varying thickness and includes a main portion  72 , a thinner projection portion  74 , and a protrusion  76 . The protrusion  76  extends in the other direction from the body  42  of the perimeter clip  26  than the rest of the inner strip flange  54 . Because of the differences in thickness between the main portion  72  and the thinner projection portion  74 , an arm receiving space  78 , as best seen in  FIG. 2 , is created between the inner filler strip  58  and the thinner projection portion  74 . The attachment clip  30 , also referred to as a rainscreen clip in the parent application, has a central portion  80 , an upper arm portion  82 , and a lower “C” channel portion  84 . The central portion  80  has an opening for receiving a fastener  88 , such as a zinc coated screw, to attach the attachment clip  30  to the wall securing device  32 . 
         [0053]    The upper arm portion  82  of the attachment clip  30  is received in the arm receiving space  76  defined by the thinner projection portion  74  of the inner strip flange  54  and the outer filler strip  60 . The “C” channel portion  84  of the attachment clip  30  has a pair of grooves  90  that receives the protrusion  76  and the top of the thinner projection  74  of the outer strip flange  48  of the perimeter clip  26 . 
         [0054]    The flange portion  68  of the outer strip flange  48  projects higher than the mounting flange  36 . Therefore, if any water works its way into the “U” shaped pocket  50 , the water will drain out over the mounting flange  36  rather than enter the chamber  64 . 
         [0055]    Still referring to  FIG. 3 , the top portion of the wall panel unit  22 , which is shown in the lower half of the FIG, hangs from the “C” channel portion  84  of the attachment clip  30 . The lower portion of the wall panel unit  22 , which is shown in the upper half of the FIG., is retained by positioning the upper arm portion  82  of the attachment clip  30  in the arm receiving space  78 . The arm receiving space  78  is best seen in  FIG. 2 . 
         [0056]    The wall securing device  32  is attached to a wall structure  92  of a building  94  and secures the perimeter clip  26  to the wall structure  92  by connecting the attachment clip  30  to the wall securing device  32 . Although in the exemplary embodiment, the wall securing device  32  is a subgirt, in other embodiments, any device capable of securing the wall panel joint  40  to the wall structure  92  can be used. 
         [0057]    The perimeter clip  26  floats on the attachment clip  30  to allow for free movement in response to thermal expansion. The attachment clip  30  is made from the same material as the perimeter clip  26 . 
         [0058]    Although the terms “horizontal” and “vertical” are used herein, the terms are merely used for distinction purposes. In some embodiments, the horizontal joint can be used in both the horizontal and vertical joint in the system. Following, both vertical and horizontal joints can be attached to a wall securing device. When the horizontal joints are used as both the vertical and horizontal joints in the system, the horizontal joint is thus representative of both joints in the system. 
         [0059]    Referring to  FIG. 4A , a front view showing the relationship of nine adjacent wall panel units is shown. The wall panel unit  22   a  is adjoining wall panel units  22   b,    22   c,    22   e,  and  22   f  with filler strips  28  extending between the units  22  respective perimeter clips  26 , as seen in  FIGS. 1-3 . Wall panel units  22   d,    22   g,    22   h,  and  22   l  are adjacent to wall panel  22   a  in that they are diagonal to the wall panel  22   a.  Whether vertical and horizontal joints are used in the system, or just horizontal joints, the joints aligned spatially vertically and horizontally intersect. This is the point of intersection. The joints are mitered, thus, the point of intersection forms a completely sealed corner. 
         [0060]    Referring to  FIG. 4B , an enlarged section of the relationship of four adjacent wall panel units  22   a,    22   b,    22   c,  and  22   d  is shown. The filler strip  60  intersects to close the gap. Whether vertical and horizontal joints are used in the system, or just horizontal joints, the joints spatially aligned vertically and horizontally intersect. This is the point of intersection. The joints are mitered, thus, the point of intersection forms a completely sealed corner. 
         [0061]    As an example of installing the wall panel system  20 , a plurality of 8 feet by 16 feet wall panel units  20  are mounted as the skin of a building. Each wall panel unit  20  has a wall panel  24  that is 8 feet high and 16 feet in length. The rectangular wall panel  24  has a perimeter clip  26  mounted on each edge to the mounting flange  36  as seen in  FIG. 3 . The mounting flanges, the four mounting flanges  36 , of each wall panel unit  20  are the top horizontal flange, a bottom horizontal flange, and a pair vertical flanges. Each perimeter clip is identical and mountable on vertical flanges and horizontal flanges. 
         [0062]    A series of wall securing devices  32  are secured to the building near ground level spaced apart based upon the structure of the building, but typically 4 to 8 feet apart. An attachment clip  30  is secured to each of the wall securing devices  32  using a fastener  88 . 
         [0063]    A series of attachment clips  30  are secured to the inner strip flange  54  at the top of the wall panel unit  22  by the “C” channel portion  84  engaging the thinner projection  74  and the protrusion  76 . In one embodiment, the attachment clips  30  are attached to the perimeter clip  26  prior to the perimeter clip  26  being secured to the wall panel  24 . This wall panel  24  with the four perimeter clips  26  is mitered and sealed at the job site with attachment clips  30  on one edge, the top edge. The wall panel unit  22 , such as  22   a  in  FIG. 4A , is positioned next to the building with the thin projection  74  of the attachment clip  30 , which is already secured to the building slipped into the arm receiving space  78  on the perimeter clip  26  on the lower edge of the panel unit  22 . These attachment clips  30 , as seen in  FIG. 3 , that are below the wall panel unit  22  retain the wall panel unit  22  and limit movement of the wall panel unit  22  in a direction perpendicular to the planar portion  34 . The series of attachment clips  30  that are already secured to the top of the wall panel unit  22  are secured to the wall securing devices  32  that are already secured to the wall structure  92  of the building  94 . The attachment clip  30 , as seen in  FIG. 3 , that is above the wall panel unit  22 , supports the weight and holds the wall panel unit  22  including the wall panel  24  and the perimeter clip  26 . 
         [0064]    The adjacent panels both vertically and horizontally, such as  22   e  and  22   f  in  FIG. 4A , can be positioned next to the building and secured. The filler strips  28  are positioned in the proper pocket  50  or  56 . The vertical filler strips  28  are installed between two adjacent already mounted wall panel units  22 . The horizontal filler strips  28  are slipped in after the adjacent panel units  22  are secured. 
         [0065]    The process is continued until the entire wall panel system  20  is built. As indicated above, the purpose of the wall panel system  20  is to allow pressure equalization between the outside environment  116  and the wall cavity  114 , as best seen in  FIG. 5 , but prevent and minimize water entry into the wall cavity  114 . The chamber  64  provides for pressure equalization by increasing the air pressure within the chamber until it equals the applied wind pressure. When the pressures are equal, water cannot enter the chamber. 
         [0066]    The length and width of the joints will vary depending on the architectural structure in which they are being used to hold wall panels. Thus, the joints can be any length or width desired. 
         [0067]    Referring now to  FIG. 5 , the vertical joint shown in  FIG. 2  is shown along with an illustration of the flow of air through the joint. The arrows represent the air. The air  110  is blasted against the wall panels  24 . The wall panel joint  40  of the wall panel system  20  defines a gutter channel  112  between the mounting flanges  36  of adjacent wall panels  24  and the outer filler strip  60 . The air enters the wall panel joint  40  through the gutter channel  112 . The air flows around the outer filler strip  60  in the “U” shaped outer pocket  50  and into the chamber or compartment  64 . The air continues to flow around the inner filler strip  58  in the “U” shaped inner pocket  56  and into the wall cavity  114 . 
         [0068]    A gap  66  is formed between the receiving edge  62  of each of the respective filler strips  58 ,  60  and the “U” shaped pocket  50  and  56  of the perimeter clips  26 . This gap  66  is designed for ventilation and thermal movement. These gaps  66  allow for pressure equalization and permeability through impermeable material. 
         [0069]    In practice, kinetic energy (wind) will increase the air pressure within the chamber until it equals the applied wind pressure. When the pressures are equal, water cannot enter the chamber. This state is attained quickly. Thus, the joints allow the system to attain optimal ventilation within the system, but prevent and minimize water entry. The joints shown in  FIGS. 2 and 3  include a number of mechanisms that both promote ventilation and prevent water from reaching the architectural structure wall (shown as  92  in  FIG. 6 ). In addition to the pressurize equalization, the flange portion  68  of the outer strip flange  48  projects higher than the mounting flange  36 , as best seen in  FIG. 3 , and prevents water entry. 
         [0070]    Referring to  FIG. 6 , a sectional view of a vertical joint of an alternative single chamber embodiment of the wall panel system  20  is shown. The wall panel joint  40  of two adjoining wall panel units  22  is shown. The wall panel  24  has the planar portion  34  and the mounting flange  36 . The two perimeter clips  26  shown are identical. Each perimeter clip  26  has the body  42  and the panel flange  44  which extends from the body  42 . The panel flange  44  forms a right angle to engage the planer portion  34  and the mounting flange  36  of the wall panel  24 . The panel flange  44  can be attached in many ways to the wall panel  24  including by rivets  46 . 
         [0071]    In addition, the perimeter clip  26  has the outer strip flange  48  which forms the “U” shaped outer pocket. The perimeter clip  26  also has the middle strip flange  52  and the inner strip flange  54  which forms the “U” shaped inner pocket  56 . 
         [0072]    Still referring to  FIG. 6 , the filler strips  26  include the inner filler strip  58  and the outer filler strip  60 . In the embodiment shown, the inner filler strip  58  and the outer filler strip  60  are identical in material but have different widths. The filler strips  60  and  58  each have a pair of receiving edges. The receiving edges of the filler strips  58  and  60  are received by the “U” shaped pockets  50  and  56  to span between the perimeter clips  26  of adjacent wall panel units  22 . The filler strips  28 , the inner filler strip  58  and the outer filler strip  60 , in conjunction with the associated perimeter clips  26  define the chamber  64 . The chamber  64  is designed for ventilation and thermal movement. This chamber  64  allows for pressure equalization and permeability through impermeable material as explained above with respect to  FIG. 5 . The adjacent perimeter clips  26 , the inner filler strip  58 , and the outer filler strip  60  form the wall panel joint  40 . 
         [0073]    Still referring to  FIG. 6 , the wall panel system  20  has an attachment clip  118  which has an arm portion  120  that is receivable in the arm receiving space  76  defined by the thinner projection portion  74  of the inner strip flange  54  and the outer filler strip  60 . In contrast to the attachment clip  30  described above with respect to  FIG. 3 , this attachment clip  118  is not required to support the weight of the wall panel unit  22 , but retain it against the wall structure  92 . Therefore the attachment clip  118  has only one groove  122  that receives the protrusion  76  of the outer strip flange  48  of the perimeter clip  26 . The attachment clip  30  has a central portion  124  that has an opening  126  for receiving a fastener  88 , such as a zinc coated screw, to attach the attachment clip  118  to the wall securing device  32 . 
         [0074]    Referring now to  FIGS. 7 and 8 , an alternative embodiment of the wall panel system  130  is shown. The system has a plurality of perimeter clips  132  that each have a third “U” shaped pocket  134  for receiving a third, extreme inner filler strip  136 . In the embodiment shown in  FIGS. 7 and 8 , the third “U” shaped pocket  134  is formed by a projecting flange  140  that extends from the panel flange  44 . The projecting flange  140  has a pair of legs  142  and  144 . The outer leg  142  is similar in shape to the middle strip flange  52  and the inner leg  144  is similar in shape to the inner strip flange  54 . The inner leg  144  has a main portion  72 , a thinner projection portion  74 , and a protrusion  76 . 
         [0075]    The pair of adjacent perimeter clips  132  in conjunction with the inner filler strip  58  and the extreme inner filler strip  136  forms a second chamber  146 . 
         [0076]    Although embodiments showing wall panel joints having 2 and 3 filler strips  28  are shown, the invention includes wall panel joints having two or more filler strips  28  and one or more chambers. Although not shown in the exemplary embodiment, the perimeter clip body can have more than two chambers. For each filler strip added to the joint, a chamber is formed. It is recognized that the perimeter clips need to be modified to include additional pockets to retain the filler strip. 
         [0077]    Again, the joint shown in  FIG. 8  is the same as the joint in  FIG. 7 , except for the addition of the attachment clip  30 . 
         [0078]    The joints are shaped to provide ventilation, pressure equalization chamber buffer(s), internal gutter systems, and thermal movement. The ventilation&#39;s function is to allow for permeability through impermeable cladding material. This second (and third, etc) pressure equalization chambers are designed to prevent water penetration for the extreme cases of kinetic energy due to a torrential rain storm or its equivalent. In addition, under extreme wind conditions with wider frequency range, the second, third, etc., chambers act as secondary buffers for effective pressure equalization. Weeps located at the bottom of the wall panel allow for escape from the wall cavity.  FIG. 1  shows a weep  150  on the lower mounting flange  36  of the wall panel unit  22   a.    
         [0079]    One embodiment of the single chamber system includes at least one single chamber vertical joint (shown in  FIG. 3 ), at least one single chamber horizontal joint (shown in  FIG. 4 ), a means for attachment for each horizontal joint, and a wall securing device for each horizontal joint. This system, in conjunction with wall panels used in the art, allows wall panels to be constructed on the outside of architectural structures. 
         [0080]    The wall panels used in the art include homogenous and composite wall panels. These are not limited to any substance, whether solid or composite, and include plastic, aluminum, zinc, platinum, titanium, copper, steel, and any other metal or material that can be used to make either homogenous or composite wall paneling. 
       EXAMPLES 
       [0081]    Referring again to  FIGS. 2 and 3 , the features in this exemplary embodiment of the horizontal and vertical joints work to prevent water from penetrating into the architectural wall. This is proven by the tests represented in the examples below. 
         [0082]    Air infiltration, water penetration, and structural performance tests of the system installed in a laboratory test chamber were performed. Wall Assembly A was tested on Apr. 8, 2005; Wall Assembly B was tested for water penetration in accordance with ASTM: E 331 on Apr. 22, 2005, and for water penetration in accordance with ASTM: E 331 but modified to monitor air flow as openings were cut in the back-up wall on May 6 and Jun. 7, 2005. The following comments describe the test procedures and results for each wall assembly. 
       DESCRIPTIONS OF WALL ASSEMBLIES 
       [0083]    WALL ASSEMBLY A—APR. 8, 2005: water penetration air infiltration and structural tests were performed on Wall Assembly A. 
         [0084]    TEST SPECIMEN—DESCRIPTION 
         [0085]    The following wall assembly was mounted in a laboratory test chamber: 
         [0086]    Dimension of Wall: 10 feet high by 10 feet wide 
         [0087]    Framing: 2″×6″ steel stud and stud track, 14-gauge 
         [0088]    Sheathing: ⅝″ thick Dens-Glass 
         [0089]    Air Barrier Membrane: Carlisle CCW-705 sheet membrane waterproofing system was installed over the Dens-Glass sheathing. An 18-gauge galvanized steel X deep hat bar was installed over the insulation. Lymo aluminum composite panels were attached to the hat bar with a continuous piece of extruded aluminum. Each panel contained two weep holes. Horizontal flashing was installed over the top of the system. 
         [0090]    WALL ASSEMBLY B—APR. 22, MAY 6, AND JUN. 7, 2005: water penetration and air infiltration tests were performed on Wall Assembly B. 
         [0091]    TEST SPECIMEN—DESCRIPTION 
         [0092]    The following wall assembly was mounted in a laboratory test chamber: 
         [0093]    Dimension of Wall: 10 feet high by 10 feet wide 
         [0094]    Framing: 2″×6″ steel stud and stud track, 14-gauge 
         [0095]    Sheathing: ⅜″ thick plexiglass 
         [0096]    The joints between abutting sheets of plexiglass were back-sealed against the steel stud framing with Dow silicone sealant. At perimeter joints, three to four inch wide strips of Carlisle CCW-705 sheet waterproofing membrane were installed. 
         [0097]    Over all perimeter joints between the perimeter of the plexiglass and the chamber walls, at vertical joints between the plexiglass sheets, and horizontally over the surface of the plexiglass where fasteners from the plexiglass to the studs were placed and where the 18-gauge galvanized steel ½″ deep bars were installed. 
         [0098]    Panel System: Two metal panel systems were installed. The directions of “right” and “left” are from the interior view: 
         [0099]    System 1 (Right Side): Standard dry seam metal panel system (prior art). 
         [0100]    System 2 (Left Side): Lymo Dry Seam 3000 panel system with double-spline system (double compartment or chamber system embodiment of present invention) 
         [0101]    TEST PROCEDURES 
         [0102]    A. Air infiltration testing was conducted in accordance with applicable provisions of ASTM Designation: E 283, “Standard Test Method for Measurement of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen.” 
         [0103]    B. Water penetration testing was conducted in accordance with applicable provisions of ASTM Designation: E 331, “Standard Test Method for Determination of Water Penetration of Exterior Windows, Curtain Walls, and Doors by Uniform Static Air Pressure Difference.” This test method was modified by making openings in the back-up wall and recording the pressure change and air flow from the chamber while the volume of air being removed from the chamber was maintained at a constant rate. The modifications were used during water testing of Wall Assembly B. 
         [0104]    TEST RESULTS 
         [0105]    WALL ASSEMBLY A—APR. 8, 2005 
         [0106]    1. AIR INFILTRATION@1.57 PSF 
         [0107]    Measured Air Leakage: 0.4 cfm 
         [0108]    Calculated Air Infiltration: 0.004 cfm per square foot 
         [0109]    The allowable increase is 0.004 cubic feet per square foot. The assembly met the requirement for air infiltration of an air barrier in the Massachusetts Energy Code. 
         [0110]    2. WATER PENETRATION 
         [0111]    Water was applied to the ‘exterior’ of the panel system at the standard rate of 5.0 gallons per hour per square foot while a negative chamber pressure of 6.24 psf was maintained on the interior of the wall assembly. 
         [0112]    Test 1 @6.24 psf: No leakage was observed on the ‘interior’ of the chamber or on the surrounding construction during or following the 15-minute test period. 
         [0113]    Test 2 @15 psf: No leakage was observed on the ‘interior’ of the chamber or on the surrounding construction during or following the 15-minute test period. 
         [0114]    WALL ASSEMBLY B—APR. 22, MAY 6, AND JUN. 7, 2005 
         [0115]    Water was applied to the exterior of the panel system at the standard rate of 5.0 gallons per hour. The following observations were made during the tests both before and after holes were made in the sheathing of the back-up wall, with air flow and pressure readings taken as part of the observations. The directions of “right” and “left” are from the interior view. 
         [0116]    Test 1 A 0 psf differential pressure was applied to the test chamber. Water was observed running down in the wall cavity behind the standard dry seam metal panel system (right side). No water was observed in the wall cavity behind the Lymo Dry Seam 3000 Panel System (left side). 
         [0117]    Test 2 A 15 psf differential pressure was applied to the test chamber behind the wall system. Water was observed running down in the wall cavity behind the standard dry seam metal panel system (right side). No water was observed in the wall cavity behind the Lymo Dry Seam 3000 Panel System (left side). The air flow from the test chamber recorded during this test was 97 cfm. 
         [0118]    Test 3 A ¼″ diameter hole was drilled through the sheathing on the back-up wall as the vacuum motor and valve controlling the rate of air extraction from the test chamber were not changed from the settings for the test chamber differential pressure of 15 psf. The pressure reading was 14.35 psf. The air flow reading was 86 cfm. 
         [0119]    Water was observed running down in the wall cavity behind the standard dry seam metal panel system (right side). No water was observed in the wall cavity behind the Lymo Dry Seam 3000 Panel System (left side). 
         [0120]    Test 4 A second ¼″ diameter hole was drilled through the sheathing on the back-up wall as the vacuum motor and valve controlling the rate of air extraction from the test chamber were not changed from the settings for the test chamber differential pressure of 15 psf. The pressure reading was 13.31 psf. The air flow reading was 91 cfm. 
         [0121]    Water was observed running down in the wall cavity behind the standard dry seam metal panel system (right side). No water was observed in the wall cavity behind the Lymo Dry Seam 3000 Panel System (left side). 
         [0122]    Test 5 A third ¼″ diameter hole was drilled through the sheathing on the back-up wall as the vacuum motor and valve controlling the rate of air extraction from the test chamber were not changed from the settings for the test chamber differential pressure of 15 psf. The pressure reading was 12.79 psf. The air flow reading was 90.6 cfm. 
         [0123]    Water was observed running down in the wall cavity behind the standard dry seam metal panel system (right side). No water was observed in the wall cavity behind the Lymo Dry Seam 3000 Panel System (left side). 
         [0124]    Test 6 A 12″×12″ hole was cut through the sheathing on the back-up wall as the vacuum motor and valve controlling the rate of air extraction from the test chamber were not changed from the settings for the test chamber differential pressure of 15 psf. The pressure reading was 0.16 psf. The air flow reading was 81.3 cfm. 
         [0125]    Water was observed running down in the wall cavity behind the standard dry seam metal panel system (right side). No water was observed in the wall cavity behind the Lymo Dry Seam 3000 Panel System (left side). 
       COMMENTS AND CONCLUSION 
       [0126]    Water was observed in the wall cavity behind a standard dry seam metal wall panel system prior to allowing the pressure drop to occur in the wall cavity. The Lymo 3000 double dry seam panel system was not observed to leak into the wall cavity prior to allowing the pressure drop to occur in the wall cavity. 
       ADDITIONAL TESTING 
       [0127]    Additional testing was preformed on Feb. 27 and 28, 2007. The testing was performed in accordance with AAMA 508-05,  Voluntary Test Method and Specification for Pressure Equalized Rain Screen Wall Cladding Systems.  The testing included air infiltration; cyclic static air pressure differential; static pressure water resistance; and dynamic pressure water resistance. 
         [0128]    The wall utilized 0.160″ thick aluminum composite cladding panels on the exterior. A 6¼″ by 6¼″ aluminum flashing was installed over the 2×12 at the sill of the mock-up. An aluminum Z-channel was installed over the flashing and the top edge, and was sealed with Carlisle EZ Flash. The base of the flashing and Z-channel were secured to the 2×12 with a continuous aluminum angle, secured with 1×1″ screws spaced 12″ on center. Panels were attached to the test wall and the sill with a continuous extruded aluminum channel clip which was fastened to the aluminum angle with #12×1″ screws spaced 16″ on center. The head of the system utilized a continuous 1⅝″ by 3″ aluminum angle secured to the 2×12 with #12×1″ screws spaced 12″ on center. The panel was secured at the head with 3¼″ long aluminum clips spaced 16″ on center which were fastened to the aluminum angle sealed with butyl. The horizontal joint was comprised of a 3″ wide continuous extruded aluminum clip secured to the panels by a subgirt and a #12×1″ screw. An aluminum composite material (ACM) filler strip  28  was installed inside the aluminum perimeter clip  26 . The subgirt was fastened to the steel studs with #14×3½″ screws. The vertical joint was comprised of a 3″ wide continuous extruded aluminum clip which was secured to the panels with pop rivets. An ACM filler strip  28  was installed inside the aluminum perimeter clip. 
         [0129]    Test Set-up: 
         [0130]    An 8′0″ wide by 8′0″ high standard wall was constructed with 14 gauge steel studs 16″ on center inside a 2×12 wood buck. The stud wall was covered by a ¼″ thick sheet of clear acrylic sealed and fastened to the exterior of the wall to simulate an air/water barrier. The Pressure Equalized Rain Screen Wall Cladding (PRWC) system was then installed onto the acrylic in a manner consistent with normal construction procedures for the system. The acrylic was calibrated to a pre-determined air leakage rate by drilling ⅛″ diameter holes in the backside of the acrylic, in a uniform pattern, making sure to create an even pressure drop and leakage rate across the wall and in each quadrant. 
         [0131]    The Air Infiltration test was pursuant to ASTM E 283-04,  Standard Test Method for Determining the Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen.  Testing was conducted at 1.57 psf positive static air pressure difference. 
         [0132]    The standard requires infiltration of between 0.418 cfm/ft 2  and 0.511 cfm/ft 2  for 1.57 psf (25 mph). The result of the testing was 0.464 cfm/ft 2 . 
         [0133]    The Cyclic Static Air Pressure Differential test was pursuant to ASTM E 1233-00,  Standard Test Method for Structural Performance of Exterior Windows, Curtain Walls, and Doors by Cyclic Static Air Pressure Differential.  Testing was conducted at 25 psf in 100 three-second cycles. The standard allows 0.08 seconds. The results were less than 0.08 seconds so the test was passed. 
         [0134]    The Static Pressure Water Resistance test was pursuant to ASTM E 331-00,  Standard Test Method for Water Penetration of Exterior Windows, Curtain Walls, and Doors by Uniform Static Air Pressure Difference.  Testing was conducted at 15.0 psf positive static air pressure difference for a 15 minute duration. Water was applied to the mock-up at a minimum rate of 5 gal/ft 2 /hr. The standard allows up to 0.64 ounces of water. Zero ounces penetrated so the test was passed. Cavity pressure readings were taken in the top left and bottom right (interior view) quadrants. 
         [0135]    The standard, like the static standard, allows up to 0.64 ounces of water to penetrate. Zero ounces penetrated so the test was passed. In the tests, water entered through the weeps and filled the gutters but did not overflow. Water came down the second right most vertical member at bottom. Furthermore, the test was conducted at a higher water penetration pressure than required. 
         [0136]    While the principles of the invention have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the invention. Other embodiments are contemplated within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.

Summary:
A wall panel joint apparatus and a system using same is disclosed. The wall panel joint includes a perimeter joint body having a predetermined size and shape. The perimeter joint body floatably attaches to at least two wall panels. Embodiments include where the wall panel joint includes one, two, or more chambers in addition to the wall cavity. The system includes at least two wall panel joints that attach the wall panels to an architectural wall. At the point of intersection of the joints, the joints are mitered. The system also includes a wall attachment device and a means for attaching the joint to the wall attachment device. The system is liquid water impermeable, air permeable, and water vapor permeable system, providing a ventilated, waterproof wall panel attachment joints for use in same.