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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to European Patent Application No. 07253268.2 entitled Cavity Wall Spacer, Building Structure, and Method, filed Aug. 20, 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a cavity wall spacer, a building structure and method. 
         [0004]    2. Related Art 
         [0005]    Many modern buildings for habitation are now constructed using cavity walls. Cavity walls are generally more effective for improving thermal insulation and inhibiting of moisture penetration compared to solid walls. Cavity walls consist of two walls or “leaves” of masonry separated by a cavity or gap. Typically, the walls are 100 mm thick, separated by a 50 mm gap. The walls may be constructed from bricks, concrete blocks, hollow clay bricks, timber framing, natural stone, or a combination of these materials. The exterior wall or leaf is usually constructed from bricks. The exterior leaf and the interior leaf are tied together at spaced intervals with wall ties spanning the cavity. 
         [0006]    Disclosed herein is an improved cavity wall spacer. 
       SUMMARY OF THE INVENTION 
       [0007]    According to a first aspect of the present invention there is provided a cavity wall spacer for determining a separation of building elements of two leaves of a wall during construction, the cavity wall spacer comprising: a support body; and a plurality of spaced projections upstanding from the support body and operable to extend across a cavity between the two leaves, each projection having a recessed channel operable to inhibit transfer of moisture from one end of each projection to another. 
         [0008]    The first aspect recognizes that a problem with the existing cavity wall spacers is that they either have no moisture barrier rib, in which case more moisture than may be desirable can track along the length of the projection from the external leaf to the internal leaf, or they have a moisture barrier rib and this causes moisture to gather and then drip into the cavity in the vicinity of the moisture barrier rib. Also, a problem with arrangements having moisture barrier ribs is that when the sheets of cavity wall spacers are stacked for storage or transport the packing density of the sheets is low since the barrier rib prevents close stacking of the sheets. Furthermore, these barrier ribs can become damaged. 
         [0009]    Accordingly, the first aspect provides at least one projection, and more typically a plurality of projections, each having a recessed channel. The recessed channel or groove helps to prevent the passage of moisture along the length of the projection which provides an efficient way of preventing moisture traveling between the two leaves of the wall. Also, a recessed channel reduces the amount of moisture which drips into the cavity since the moisture is more likely to track back along the surface of the projection. Additionally, providing a recessed channel ensures no external obstruction on the projections which helps to achieve a significantly improved stacking density. Furthermore, the projections are less prone to any damage since there are no external protrusions. 
         [0010]    In one embodiment, the recessed channel is operable to cause moisture flowing from one end of the projection to another to collect therein. Accordingly, the recessed channel provides a depression or gully into which any moisture traveling along the length of the projection may accumulate. 
         [0011]    In one embodiment, the recessed channel is operable to cause the moisture collected therein to gather at a moisture-release point. Hence, the channel acts as a conduit along which the accumulated moisture may flow to a moisture-release point. It will be appreciated that in practice small droplets will accumulate in the recessed channel which will combine into larger droplets which, once a sufficient mass has been achieved, will overcome surface tension and will flow along the recessed channel under gravity to the underside of the recessed channel when installed in the cavity. The underside of the channel when installed in the cavity may provide two moisture-release points, one at each side of the recessed channel. 
         [0012]    In one embodiment, each projection is tapered towards its distal end and the recessed channel is operable to direct moisture gathered at the moisture-release point towards that projection&#39;s proximal end. Hence, in a tapered arrangement, any moisture gathered at the moisture-release point (which is typically on the underside of the projection when installed in the cavity) will be likely to travel under gravity back along the outer surface of the projection back towards the support body rather than drip into the cavity itself. 
         [0013]    In one embodiment, the recessed channel is located between proximal and distal ends of the projection. 
         [0014]    In one embodiment, the recessed channel is located towards the distal end of the projection. 
         [0015]    In one embodiment, the recessed channel is located in a distal face of the projection. Hence, rather than be located along the length of the projection, the recessed channel may be formed in the tip of the projection. 
         [0016]    In one embodiment, the recessed channel extends at least partly circumferentially about the projection. 
         [0017]    In one embodiment, the recessed channel extends entirely circumferentially about the projection. 
         [0018]    In one embodiment, each projection has two converging lateral walls. 
         [0019]    In one embodiment, each projection has a lenticular cross-section. 
         [0020]    In one embodiment, each projection is hollow. It will be appreciated that providing a hollow projection increases the stacking density. 
         [0021]    In one embodiment, the support body and the projections are integrally formed. 
         [0022]    In one embodiment, each projection extends transversely of the support body. 
         [0023]    In one embodiment, each projection extends from a face of the support body. 
         [0024]    According to a second aspect of the present invention there is provided a building structure incorporating one or more cavity wall spacers according to the first aspect in a cavity wall of the building structure. 
         [0025]    In one embodiment, the cavity wall spacers are located at spaced intervals in the cavity wall of the building structure 
         [0026]    According to a third aspect of the present invention there is provided a method of erecting a building having a cavity wall of two or more leaves comprising the steps of: erecting part of one leaf of the cavity wall of the building; securing to the erected part of the one leaf of the cavity wall a cavity wall spacer according to the first aspect, and erecting at least part of another leaf of the cavity wall of the building in a position spaced from the one leaf by a distance determined by the cavity wall spacer. 
         [0027]    In one embodiment, the spacer device is orientated in the cavity wall of the building so that the support body of the cavity wall spacer is against an inner face of an exterior leaf of the cavity wall and the plurality of projections of the support body extends toward an interior leaf of the cavity wall of the building. 
         [0028]    In one embodiment, the cavity wall spacer is orientated so that distal ends of the plurality of projections abut an inner face of the interior leaf of the cavity wall of the building. 
         [0029]    Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views. 
           [0031]      FIG. 1  is a perspective view of a cavity wall spacer according to one embodiment; 
           [0032]      FIG. 2  is a side view of the cavity wall spacer of  FIG. 1 ; 
           [0033]      FIG. 3  is a sectional view of a cavity wall of a building incorporating the spacer device of  FIG. 1 ; 
           [0034]      FIG. 4  is a sectional view showing the stacking arrangement of a number of sheets of spacer devices of  FIG. 1 ; 
           [0035]      FIG. 5  is a perspective view of a sheet cavity wall spacers of  FIG. 1 ; 
           [0036]      FIG. 6  is a perspective view of a cavity wall spacer of a further embodiment; 
           [0037]      FIG. 7  shows further views of the cavity wall spacer of  FIG. 6 ; and 
           [0038]      FIG. 8  is a perspective view of a sheet of cavity wall spacers of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    In the following description, numerous specific details are set forth in order to provide a more thorough description of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the invention. 
         [0040]    For a cavity wall to effectively work as a moisture barrier, the cavity or gap should not be bridged in any way. A cavity wall spacer may be used to inhibit the transfer of moisture from the exterior leaf to the interior leaf in one or more embodiments. GB 2 388 614, which is incorporated herein by reference, illustrates an example of a spacer that may be used in this manner. The cavity wall spacer disclosed herein, comprises a novel configuration which provides various advantages which will be apparent from the description below. 
         [0041]    Referring to  FIG. 1 , there is shown a cavity wall spacer, generally  11 , according to one embodiment. The cavity wall spacer  11  is integrally formed by vacuum molding and has a support body  12  with a plurality of projections  13  extending transversely from the plane of the support body  12 . Although  FIG. 1  shows just one projection  13 , this is just one portion of the support body  12  which is a laminar sheet having overall dimensions of 1200 mm by 450 mm and a depth of 50 mm with a plurality of these projections  13  extending therefrom as shown in more detail in  FIG. 5 . The support body  12  and the projections  13  of the spacer device  11  are made from a plastics material which is high-density polyethylene (HDPE) having a thickness of around 2 mm. The plurality of projections  13  are longitudinal and have a proximal end  14  located adjacent to an inner face of the support body  12  and a distal end  15  located away from the support body  12 . Each of the projections  13  are spaced away from each other typically by a distance of 260 mm between centers horizontally and 125 mm between centers vertically. The projections  13  have a lenticular shape. A recessed channel or groove is formed as an indentation or depression in the surface of the projection  13 . In this arrangement, the recessed channel  16  extends entirely circumferentially about the projection  13 . The spacer device  11  is primarily for use in a cavity wall of a building structure to prevent or at least inhibit water or moisture from penetrating the building. 
         [0042]    Referring to  FIG. 2 , there is shown a sectional view of the spacer device  11  having the support body  12  and the plurality of projections  13 . The recessed channel  16  spaced towards the distal face  15  of the projection  13 . 
         [0043]    Referring to  FIG. 3 , the cavity wall spacer  11  is incorporated in a cavity  17  of a cavity wall  18  of a building structure (again, just a portion of the complete sheet is shown). The cavity wall  18  has an exterior wall  19  and an interior wall  20  and may optionally include a layer  21  of an insulating material on an inner face of the interior wall  20 . Alternatively, the insulation layer  21  may be separate from the cavity wall spacer  11 , and the cavity wall spacer  11  may retain the separate insulation layer  21  in place against the inner face of the interior wall  20 . The exterior and interior walls  19 ,  20  are constructed from bricks, although they may also be constructed from concrete blocks, hollow clay bricks, timber framing or natural stone. The spacer device  11  is located in the cavity  17  of the cavity wall  18 . 
         [0044]    The support body  12  of the spacer  11  lies against an inner face of the exterior wall  19  with the plurality of projections  13  extending toward the inner face of the interior wall  20 . The recessed channels  16  are located towards the distal end of the projection  13  in the region near the inner face of the interior wall and function as a “water bar” to prevent or hinder the penetration of water or moisture into the interior wall  20  of the building. Any water which enters the cavity  17  flows along the outer surface of the projections  13  to the recessed channel  16  whereupon further water penetration into the cavity  17  is prevented. The recessed channel  16  causes water droplets to form and, when a sufficiently sized droplet has formed, it is guided within the conduit formed by the recessed channel around the exterior of the projection  13  to two moisture-release points  17   a ,  17   b  which are located on either side of the recessed channel  16  at the lower intersection of the two arcs forming the lenticular cross-section of the projection  13 . From here, the water droplet will either drip downwardly from the projections  13  to the ground surface where weep holes (not shown) may be provided in the exterior wall to drain the water from the cavity  17 . Alternatively, the water droplet will track back along the external surface of the projection  13  towards the exterior wall  19 . Eventually, the water droplet will then gather on the ground surface in the vicinity of the weep holes in the exterior wall  19 . 
         [0045]    The projections  13  have a lenticular shape having upper and lower ridges defined by the region where the converging arcs intersect. The side walls of the projections are steeply angled relative to the axis of the projection  13  which causes the water droplets to travel down the walls to the lower ridge. 
         [0046]    As shown in  FIG. 5 , the laminar support body  12  will typically have dimensions of 1200 mm by 450 mm and the projections  13  are spaced across a face of the support body  12  and formed into three rows and five columns. 
         [0047]    A plurality of the spacer devices is typically installed in a cavity wall of a building in a plurality of rows and columns. Typically, wall ties (not shown) are located in the cavity  17  at regular spaced intervals. The substantially horizontal spacing between adjacent wall ties is usually about 900 mm and the substantially vertical spacing between adjacent wall ties is usually about 450 mm. These measurements correspond approximately to the dimensions of the spacer device so that it may be positioned in a cavity wall between spaced wall ties. 
         [0048]    Each spacer device may be connected to another spacer device in the cavity wall using H-shaped connection elements (not shown) having two longitudinal parallel walls joined together at a middle region thereof by an integral longitudinal member so as to define U-shaped channels, each of which can receive a part of the support body of adjacent spacer devices. In this way, one spacer device can be connected to another spacer device to create a sufficiently stable structure of spacer devices in the cavity wall. 
         [0049]    Referring now to  FIG. 4 , there is shown a plurality of spacer devices stacked upon each other. As can be seen, a high packing density can be achieved since the absence of any external protrusions enables the spacer devices to readily slide over each other and stack in close formation. 
         [0050]    Referring to  FIG. 6 , there is illustrated a spacer device, generally  11 ′ according to a further embodiment. Once again, the spacer device  11 ′ is integrally formed by vacuum molding and has a support body  12 ′ with a plurality of projections  13 ′ extending transversely from the plane of the support body  12 ′. The support body  12 ′ is a laminar sheet. The support body  12 ′ and the projections  13 ′ of the spacer device  11 ′ are made from a plastics material. The plurality of projections  13 ′ are longitudinal and have a proximal end  14 ′ located adjacent to the support body  12 ′ and a distal end  15 ′ spaced away from the support body. The projections  13 ′ have a generally lenticular shape. 
         [0051]    A recessed channel  16 ′ is formed in the distal end  15 ′. The recessed channel  16 ′ extends entirely circumferentially around distal end  15 ′. The recessed channel  16 ′ functions in a similar way to the arrangement shown in  FIGS. 1 to 3  and acts to divert moisture within the cavity  17  away from the inner wall  20 . 
         [0052]    As shown in  FIG. 8 , the laminar support body  12 ′ will typically have dimensions of 1200 mm by 450 mm and the projections  13 ′ are spaced across a face of the support body  12 ′ and formed into three rows and five columns. 
         [0053]    Hence, it can be seen that the cavity wall spacers  11 ,  11 ′ both inhibit the transfer of moisture from the external wall to the internal wall. Also, the recessed channel  16 ,  16 ′ reduces the amount of moisture which drips into the cavity since the moisture is more likely to track back along the surface of the projection. Additionally, a high staking density of the cavity wall spacers  11 ,  11 ′ can be achieved since there are no external protrusions which would otherwise prevent the exterior of the spacer device  13 ,  13 ′ from closely mating with the interior of a further cavity wall spacer stacked thereon. Furthermore, by avoiding any external protrusions the risk of damage to the cavity wall spacers  11 ,  11 ′ is reduced. 
         [0054]    While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of this invention. In addition, the various features, elements, and embodiments described herein may be claimed or combined in any combination or arrangement.

Summary:
A cavity wall spacer, building structure, and method are disclosed. The cavity wall spacer determines a separation of building elements of two leaves of a wall. The cavity wall spacer comprises: a support body; and a plurality of spaced projections upstanding from the support body and operable to extend across a cavity between the leaves, each projection having a recessed channel operable to inhibit transfer of moisture from one end of each projection to another. The recessed channel prevents the passage of moisture along the length of the projection to prevent moisture from traveling between the two leaves of the wall, and reduces the amount of moisture which drips into the cavity. The recessed channel has no external obstructions and thus allows significantly improved stacking density. The projections are less prone to any damage since there are no external protrusions.