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TECHNICAL FIELD 
       [0001]    The present invention relates to elongated hollow building elements that are combined to form a wall or panel and more particularly to such building elements that are extruded for plastics material and are secured together by snap engagement. The building elements can be used in the construction of basement walls, liquid and granular storage tanks and other like structures. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to the building element described in U.S. Pat. No. 7,703,248. 
         [0003]    Where walls are exposed to moisture, such as walls of water storage tanks and building walls below ground level, typically waterproofing is applied to the walls that are exposed to the moisture. In the construction of conventional concrete and reinforced masonry walls, the walls need to be protected from moisture as exposure to moisture over time will cause degradation of the concrete and corrosion of the steel. A still further problem is mould, mildew and fungus and bacterial development on the walls. To address this issue typically a waterproof membrane is applied to inhibit water reaching the concrete or reinforced masonry wall. It is also not unusual to provide a gap between an earth surface and the wall to enable a water proofing membrane to be applied. Typically the gap can be a metre. This gap can be considered a safety issue for workers. 
         [0004]    The above construction of walls that are to exist in a damp environment has a number of disadvantages in that if the waterproofing fails then the wall will degrade. A further disadvantage is the loss of floor area should a gap be required between the wall and an earth surface. 
       OBJECT OF THE INVENTION 
       [0005]    It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages. 
       SUMMARY OF THE INVENTION 
       [0006]    There is disclosed herein an extruded hollow longitudinally elongated building element into which concrete is to be poured, the element being extruded so as to be integrally formed and comprising: 
         [0007]    a pair of longitudinally extending spaced walls which are generally longitudinally coextensive and longitudinally parallel; 
         [0008]    a plurality of longitudinally extending spaced transverse webs joining the side walls, the webs including a first and a second web; 
         [0009]    a pair of longitudinally extending grooves, each of the grooves being formed in a respective one of the side walls; 
         [0010]    a pair of longitudinally extending end flanges, each of the end flanges extending from a respective one of the walls; 
         [0011]    a pair of longitudinally surfaces that diverge from the first web toward the grooves; 
         [0012]    a sealing projection extending from each flange and extending longitudinally thereof; and wherein 
         [0013]    the end flanges and grooves are positioned and configured to engage a respective one of the grooves of a respective one of the flanges of a like element, and the end flanges are resilient deformed by engagement longitudinal surface of the like element so as to be resilient deformed such that, when the end flanges are moved in a transverse direction relative to the diverging surfaces of the like element, there is a resilient deformation of the end flanges to allow snap engagement of each end flange in a respective one of the grooves to thereby secure the elements together by snap engagement, and the sealing projections extend transversely from their associated flange toward the other element to aid in sealingly connecting the. elements. 
         [0014]    Preferably, each end flange includes a first portion extending transversely from the first wall, and a second portion extending generally transverse relative to the first portion so as to project into the associated groove of the like element. 
         [0015]    In one preferred form, said sealing element projects from said portion. 
         [0016]    In a further preferred form, said sealing projection extends from said second portion. 
         [0017]    Preferably, each groove is provided by a groove providing portion extending longitudinally of the element, the groove providing portion having a sealing projection extending longitudinally of the element and extending into the groove so as to be operatively associated with the sealing element of the second portion to aid in sealingly connecting the elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings wherein: 
           [0019]      FIG. 1  is a schematic top plan view of the walls of a building basement; 
           [0020]      FIG. 2  is a schematic top plan view of portion of one of the walls of  FIG. 1 ; 
           [0021]      FIG. 3  is a schematic top plan view of a further portion of one of the walls of  FIG. 1 ; 
           [0022]      FIG. 4  is a schematic top plan view of a building element used to form the walls of the basement of  FIG. 1 ; 
           [0023]      FIG. 5  is a schematic top plan view of a further building element used in forming the walls of  FIG. 1 ; 
           [0024]      FIG. 6  is a schematic enlarged view of portion of the elements used to form the walls of  FIG. 1 ; and 
           [0025]      FIG. 7  is a schematic top plan view of an alternative portion of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    In  FIG. 1  of the accompanying drawings there is schematically depicted the basement  10  of a building. The basement  10  may be below ground level. 
         [0027]    The basement  10  includes walls  11  that may be straight or curved. Each of the walls  11  is formed by a plurality of elongated building elements  12 . Each building element  12  is hollow and is extruded from plastics material. Each element  12  has a pair of longitudinally extending side walls  13  that are longitudinally parallel. In  FIG. 3  the element  12  illustrated has the walls  13  also transversely parallel and generally flat. The element  12  of  FIG. 5  has longitudinally extending side walls  14  and  15  that provide for the construction of curved walls and corners, with the walls  11  inclined by a desired angle  29 . The inner wall  15  is of a shorter transverse width relative to the outer wall  14 . 
         [0028]    Each of the elements  12  has a plurality of transverse webs  16  and end webs  17  and  18 . The webs  16  of the element  12  of  FIG. 4  is joined to the side walls  13  by connecting webs  19 . The connecting webs  19  are inclined so as to converge from their connection with the side walls  13  to the associated web  16 . 
         [0029]    The end web  18  has extending from it longitudinally extending ramp surfaces  20  that diverge from the web  18  toward the side walls  13 ,  14  and  15 . The surfaces  20  extend to longitudinally extending grooves  21 . 
         [0030]    Extending from the end web  17  are flanges  22  that in the embodiment of  FIG. 4  are generally parallel and coextensive. 
         [0031]    Like elements  12  are connected by transverse relative movement between the elements  12 . In particular the flanges  22  of one of the elements  12  moves transversely across the surfaces  20  so as to be resiliently deflected apart, with the flanges  22  then snap engaging within the recesses  21  to thereby connect adjacent elements  12 . 
         [0032]    As best seen in  FIGS. 6 and 7  each flange  22  includes a first flange portion  23  that extends from the web  17 , and a second flange portion  24  that extends from the first flange portion  23 . The second portion  24  is to be located in the recess  21 . The portions  23  of each element  12  are generally parallel and coextensive and extend generally transverse to the associated web  17 . The second portion  26  projects from the first portion  23  in a direction generally parallel to the web  17 . 
         [0033]    Each groove  21  is provided by a groove providing portion  25 , the portions  25  of each element  12  being generally parallel and coextensive. The portions  25  are of a “U” shaped transverse cross section so as to receive the portion  24 . 
         [0034]    In the embodiment of  FIG. 6 , the first flange portion  23  is provided with a longitudinally extending seal projection  26  that is shaped like a barb. The projection  26  extends from the first portion  23  toward the other element  12 . The projection  26  may actually engage the other element  12  or be slightly spaced therefrom. In such instances, wet concrete delivered to the cavities  30  would sealingly connect each sealing projection  26  to the adjacent element  12 . The projection  26  aids in sealingly connecting engaged elements  12 . 
         [0035]    When elements  12 , as shown in  FIG. 6 , are connected, the second portion  24  would move along the surface  20  so as to cause resilient outward deflection of the first portions  22  until the second portions  24  were aligned with the groove  21  so as to snap engage therein. 
         [0036]    In the embodiment of  FIG. 7 , there is provided a pair of sealing projections  27  and  28 . The projection  27  extends from the second portion  24  while the projection  28  extends from the recess providing portion  25 . The projections  27  and  28  engage, or are located adjacent each other so that the gap therebetween is sealed by wet concrete. 
         [0037]    The projections  26 ,  27  and  28  extend the entire longitudinal length of each of the elements  12 .

Summary:
A building element that is an elongated extrusion of plastics material. The element can be used to form straight or curved walls. Like elements are secured together by transverse relative movement and snap engagement of flanges in recesses. En one embodiment the element has a longitudinally extending seal projection that aids in sealingly connecting engaged elements.