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CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 60/881,151, filed on Jan. 19, 2007, titled “POLYURETHANE ROCK FAUX FENCE WALL,” the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to construction and installation techniques for walls. More particularly, the present invention pertains to a plastic wall construction and installation method. 
       BACKGROUND OF THE INVENTION 
       [0003]    The addition of stone fences and retaining walls can greatly improve the aesthetic appeal of a property as well as provide privacy and/or structural support for landscaping features such as terraces and the like. In addition, a stone wall may require no maintenance for many years. Unfortunately, stone walls are extremely expensive due to the high cost of materials and labor involved. Furthermore, conventional stone wall are constructed on site and are therefore subject to the weather. Excessive rain or freezing temperatures can cause delays and raise costs. 
         [0004]    Another disadvantage of conventional stone walls is the required footing upon which the walls are constructed. Generally, footing are twice the thickness of the walls being constructed thereon. In regions subject to freeze/thaw cycles, the footings must be placed below the frost level which may be several feet below the surface in the northern areas of the United States. The construction of these footings adds considerable costs to the construction of conventional walls. Moreover, conventional stone wall construction generally disturbs the ground and any plant roots or buried cables and pipes in the vicinity. Accordingly, it may not be possible to construct conventional stone walls near mature plantings. 
         [0005]    Accordingly, it is desirable to provide a method of constructing and installing walls capable of overcoming the disadvantages described herein at least to some extent. 
       SUMMARY OF THE INVENTION 
       [0006]    The foregoing needs are met, to a great extent, by the present invention, wherein in one respect a method of constructing and installing walls is provided. 
         [0007]    An embodiment of the present invention pertains to a method of installing a wall. In this method, a placement area for a set of prefabricated wall sections is determined. The placement area includes a starting end and a terminating end. A wall section of the set of prefabricated wall sections includes a first layer of urethane foam, a second layer of urethane foam, an extension and depression to mate with a corresponding depression and extension of another wall section of the set of prefabricated wall sections, and a through bore extending from an upper face of the extension, passing through the extension and exiting a lower face of the extension. During installation, surface vegetation is removed from the placement area in response to surface vegetation being present on the placement area, the soil is compacted in the placement area, and a first wall section of the set of prefabricated wall sections is placed at the starting end. In addition, the first wall section is secured to the starting end, a next wall section of the set of prefabricated wall sections is placed at the placement area, and the next wall section is affixed to a previously secured wall section of the set of prefabricated wall sections. Furthermore, the next wall section is secured to the placement area, the steps of placing, affixing, and securing next wall section are continued until the terminating end is reached. Moreover, a last wall section of the set of prefabricated wall sections is placed at the terminating end and the last wall section is affixed to the previously secured wall section. 
         [0008]    Another embodiment of the present invention relates to a wall section. The wall section includes a first layer of urethane foam, a second layer of urethane foam, an extension and depression to mate with a corresponding depression and extension of another wall section of the set of prefabricated wall sections, and a through bore extending from an upper face of the extension, passing through the extension and exiting a lower face of the extension. 
         [0009]    Yet another embodiment of the present invention pertains to a column including a first layer of urethane foam and a second layer of urethane foam. The first layer has a density of about 80 kilograms per cubic meter (“Kg/m 3 ”) to about 320 Kg/m 3  and the second layer has a density of about 1.5 Kg/m 3  to about 15 Kg/m 3 . 
         [0010]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0011]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0012]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a wall section suitable for use with an embodiment of the invention. 
           [0014]      FIG. 2  is a cross-sectional view of the wall section in accordance with an embodiment of the invention. 
           [0015]      FIG. 3  is a flow diagram for a method of generating the wall section in accordance with an embodiment of the invention. 
           [0016]      FIG. 4  is a perspective view of an installed wall suitable for use with an embodiment of the invention. 
           [0017]      FIG. 5  is a cross-sectional view of the installed wall in accordance with an embodiment of the invention. 
           [0018]      FIG. 6  is a flow diagram for a method of generating the installed wall in accordance with an embodiment of the invention. 
           [0019]      FIG. 7  is a perspective view of a male and female end joint suitable for use with another embodiment of the invention. 
           [0020]      FIG. 8  is a perspective view of an assembled male/female joint in accordance with  FIG. 7 . 
           [0021]      FIG. 9  is a perspective view of a completed male/female joint in accordance with  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The present invention provides a method of constructing a wall that appears to be made from stone. In fact this novel method includes the use of plastic molded to resemble stone. It is an advantage of embodiments of the invention that the wall is less expensive to produce and install and may be installed more rapidly than an actual stone wall. 
         [0023]    Preferred embodiments of the invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout.  FIG. 1  is a perspective view of a wall section  10  suitable for use with an embodiment of the invention. As shown in  FIG. 1 , the wall section  10  includes one or more extensions  12  and one or more depressions  14 . As shown herein the extensions  12  and depressions  14  of one wall section  10  are configured to mate with the depressions  14  and extensions  12  of another wall section  10  to form a joint. 
         [0024]    The extension  12  includes a through bore  16  (Shown in  FIG. 5 ). As shown herein, the through bore  16  is configured to pass from an upper face of the extension  12 , through the body of the extension  12 , and to a lower face of the extension  12 . In general, the through bore  16  is sized to accept a rod or spike. As shown herein, by driving the rod or spike through the through bore  16  and into the ground below, the wall section  10  may be anchored to the ground. 
         [0025]    Also shown in  FIG. 1 , the extension  12  and depression  14  include a plurality of bearing or mating surfaces  18   a  to  18   n . Examples of mating surfaces  18   a  to  18   n  include the illustrated mating surfaces  18   a  to  18   h . In response to introducing the mating surfaces  18   a  to  18   h  of a first wall section  10  to the mating surfaces  18   a  to  18   h  of a second wall section, respective mating surfaces  18   a  to  18   h  facilitate alignment and act to reduce rotational movement of the first wall section  10  relative to the second wall section  10 . In addition, the mating surfaces  18   a  to  18   h  are configured to provide bonding surfaces. That is, the mating surfaces  18   a  to  18   h  are configured to accept an adhesive. In this manner, the first wall section  10  may be affixed to the second wall section  10 . 
         [0026]      FIG. 2  is a cross-sectional view A-A of the wall section  10  in accordance with an embodiment of the invention. As shown in  FIG. 2 , the wall section  10  includes a first layer  30  and a second layer  32 . In general, the first layer  30  is a relatively high density, high strength, and high durability material. In a particular example, the first layer  30  may include a urethane foam having a density of about 80 kilograms per cubic meter (“Kg/m 3 ”) to about 320 Kg/m 3  and having a compressive strength of greater than about 4.5 kilogram per square centimeter (“Kg/cm 2 ”). Specific examples of materials suitable for use in the first layer  30  include those described in U.S. Pat. No. 5,185,383. Other examples of materials suitable for use in the first layer  30  include those manufactured by Urethane Technology Company, Inc. of Newburgh, N.Y., 12550 U.S.A. 
         [0027]    Generally, the second layer  32  is comparatively lower in density and compression strength as compared to the first layer  30 . This lighter weight layer provides added strength while reducing weight of the wall section. The cost of materials used in the fabrication of the wall section are typically based on the weight of the materials used. By reducing the overall weight of the wall section  10 , the production cost may be reduced. 
         [0028]    In a particular example, the second layer  32  may include a urethane foam having a density of about 1.5 Kg/m 3  to about 15 Kg/m 3 , and a compressive strength of less than about 1.5 Kg/cm 2 . Specific examples of materials suitable for use in the second layer  32  include those described in U.S. Pat. No. 5,185,383. Other examples of materials suitable for use in the second layer  32  include those manufactured by Urethane Technology Company, Inc. of Newburgh, N.Y., 12550 U.S.A. 
         [0029]    In addition, the first layer  30  includes a set of surface characteristics  34  consistent with a stone wall or other molded item. In a particular example and as shown in  FIG. 1  and  FIG. 2 , the wall section  10  includes the appearance of a stone wall. More particular, the set of surface characteristics  34  may include mortar lines, a stone-like texture, stone mimicking coloration, and the like. In other examples, the set of surface characteristics  34  may be configured to mimic dry stacked stone (e.g., without mortar lines), wood, plaster, concrete, and the like. 
         [0030]      FIG. 3  is a flow diagram for a method  40  of generating the wall section  10  in accordance with an embodiment of the invention. Prior to generating the wall section  10 , a variety of processes may be performed. In no particular order, these processes may include one or more of: wall section design; building and testing mockups; obtaining materials; and the like. As shown in  FIG. 3 , the method  40  may generally include constructing a mold at step  42  and fabricating the wall section  10  at step  44 . 
         [0031]    To construct the mold, at step  46  a pattern for the wall section  10  may be built or fabricated. In a specific example, a stone wall may be laid in a traditional manner or an existing stone wall may be prepared for use as the pattern. For example, pattern preparations may include applying a release coat, modifications to form the extensions and/or the depressions, and the like. 
         [0032]    At step  48 , the pattern may be incased in an impression material or molding material. In general, the molding material may include any suitable molding material. Examples of suitable materials include: sand, concrete, plaster, epoxy, plastics, resins, and the like. In a particular example, silicone rubber may be applied to the pattern in a liquid form and allowed to solidify. Specific examples of suitable silicone rubber include VI-SIL V340 and other products manufactured by Rhodia Inc of Cranbury N.J. 08512, U.S.A. 
         [0033]    At step  50 , the pattern may be removed from the mold. In various examples, the pattern may be incased in two separate halves, a partition may be placed along the outside of the pattern, or the molding material may be cut to form two or more mold pieces. In other examples, the mold may be sufficiently flexible to be removed from the pattern as a unitary piece. As such, the method of removing the mold from the pattern may depend upon the shape of the pattern and the characteristics of the mold. 
         [0034]    To fabricate the wall section  10 , the first layer  30  is applied to an inside surface of the mold at step  52 . For example, an about 80 Kg/m 3  to about 320 Kg/m 3  density urethane foam may be sprayed into the mold. That is, two liquid components of the urethane may be pressurized and dispensed from a spray gun for example. As the components are ejected from the spray gun, they are atomized and mix in the air or on the sprayed surface. The thickness of the first layer  30  may depend upon a variety of factors such as, for example, the overall size of the wall section  10 , anticipated use for the wall section  10 , empirical data, and the like. The first layer  30  may be applied in one or more applications and may be allowed to cure or not prior to application of the second layer  32 . 
         [0035]    If the first layer  30  is to be colored, a coloring agent may be applied to the mold prior to application of the first layer  30 , may be mixed in with the liquid components, and/or may be applied after the wall section  10  is removed from the mold. In another example, the coloring agent may be added to one or both urethane components A/B prior to being sprayed in the mold. 
         [0036]    At step  54 , the second layer  32  is applied to the applied first layer  30 . For example, an about 1.5 Kg/m 3  to about 15 Kg/m 3  density urethane foam may be sprayed onto the first layer  30  In another example, the urethane components A/B may be mixed in a container and poured into or otherwise introduced to the mold. The thickness of the second layer  32  may depend upon a variety of factors such as, for example, the overall size of the wall section  10 , anticipated use for the wall section  10 , empirical data, and the like. The second layer  32  may be applied in one or more applications and may completely fill the mold (minus the first layer  30 ) or a void may be allowed to remain. 
         [0037]    At step  56 , the cast wall section  10  may be cured. In various embodiments, curing may be performed via heat activation, allowing a specified length of time to elapse, via exposure to ultraviolet light, and the like. In a specific example, the cast wall section  10  may be allowed to cure at room temperature for 15 minutes to 24 hours before being removed from the mold. 
         [0038]    At step  58 , the wall section  10  is removed from the mold. For example, in a manner similar to removal of the pattern from the mold, the mold may be separated into pieces that are removed from the wall section  10  or the mold may be removed as a unitary structure. 
         [0039]    Following removal from the mold, the wall section  10  may be cleaned, milled, sanded, colored, or otherwise treated. For example, surface voids may be filled, sprue and excess flash may be cut or milled flush, and the like. In another example, paint or other colorized coating may be applied to all of part of the wall section  10 . 
         [0040]    Of note, embodiments of the invention are not limited to fabricating wall sections, but rather, any suitable structure may be fabricated according to the method  40 . In a particular example, a suitable structure that may be fabricated according to the method  40  may include columns and the like. 
         [0041]      FIG. 4  is a perspective view of an installed wall  70  suitable for use with an embodiment of the invention. As shown in  FIG. 4 , the wall  70  includes a plurality of the wall sections  10  joined to form the wall  70 . In the particular example shown, the wall  70  include a pair of end sections  72  flanking a mid section  74 . However, the wall  70  is not limited to the pair of end sections  72  flanking mid section  74  but rather, may include any suitable number of the mid sections  74  and end sections  72 . In addition, while the wall  70  is illustrated as a generally straight wall, in other examples the wall  70  may include one or more angled section and/or may include curved or serpentine elements. As shown in  FIG. 4 , the mid sections  74  and end sections  72  mate together to generate a unitary appearance. 
         [0042]      FIG. 5  is a cross-sectional view of the installed wall  70  in accordance with an embodiment of the invention. As shown in  FIG. 5 , the wall  70  includes two of the mid sections  74  and two of the end sections  72 . Also shown in  FIG. 5 , the wall sections  10  are anchored via a rod  80  passing through the through bore  16 , through a layer of compacted gravel  82 , and into underlying soil  84 . To further secure one wall section  10  to the next, an adhesive  86  may be disposed at the interface of the mating surfaces  18   a  to  18   n.    
         [0043]    According to various examples, the bottom of the wall  70  may be disposed at or below a ground level  88 . For example, a layer of sod  90  may be removed from the area of wall construction. In addition, the soil  84  may be removed to a suitable depth. In a particular example, about 1 to 12 inches of soil may be removed. More particularly, about 3 inches of the soil  84  may be removed. 
         [0044]      FIG. 6  is a flow diagram for a method  100  of generating the wall  70  in accordance with an embodiment of the invention. Prior to generating the wall  70 , a variety of processes may be performed. In no particular order, these processes may include one or more of: landscape design; wall design; marking out the wall location; obtaining materials; and the like. As shown in  FIG. 6 , the method  70  may generally include preparing a base at step  102  and installing the wall section  10  at step  104 . 
         [0045]    To prepare the base, at step  106  any surface vegetation may be removed from the area the wall  70  is to be placed. In a specific example, the sod  90  from an area marked out for wall placement may be remove with a sod cutter or shovel. The removal of the sod  90  is to facilitate creating a stabile base. If left in place, the sod  90  may die and decompose—possibly undermining the wall  70 . 
         [0046]    At step  108 , the soil  84  may be removed to a suitable depth. In general, the soil  84  is removed to provide a shallow depression for the gravel  82  placed at step  110 . A suitable depth to provide a shallow depression ranges from about 1 inch to about 12 inches. More particularly, a depth of about 3 inches to about 6 inches is suitable. In addition, the soil  94  at or near the ground level  88  may be less compacted and may contain a greater amount of vegetative matter. By removing this upper layer, the base upon which the wall sections are placed may be more stabile. Following removal, the underlying soil  84  may be compacted. In addition, a permeable membrane such as builder&#39;s felt or the like may be placed on the soil  84  to limit movement of the soil  84  into the gravel  82  placed at step  110 . 
         [0047]    At step  110 , the gravel  82  may be placed in the depression made at steps  106  and  108 . For example, a sufficient amount of the gravel  82  may be placed in the depression to bring the level up to about the ground level  88 . In addition, the gravel  82  may be compacted to consolidate or stabilize the layer of gravel  82 . 
         [0048]    To install the wall  70 , a first wall section  10  is disposed upon the compacted gravel  82  at a starting location at step  112 . In general, the starting location occurs at one end of the area for the wall installation. As such, typically the first wall section  10  will include the end section  72 . Once the wall section  10  is determined to be properly placed, the rod  80  is driven through the through bore  16 , the gravel  82 , and into the soil  84  at step  114 . The length of the rod  80  and the depth to which the rod  80  is driven into the soil  84  may vary according to a variety of factors. For example, the factors may include one or more of the consistency of the soil  84 , the size of the wall  70 , the designed load on the wall  70 , empirical data, and the like. 
         [0049]    At step  116 , the adhesive  86  may be applied to secure a next wall section  10  to the installed wall section  10 . For example, the adhesive  86  may be applied to one or more of the mating surfaces  18   a  to  18   n . The adhesive may be applied according to the manufacturer&#39;s instruction. For example, instructions provided by the manufacturer may recommend cleaning the parts to be affixed with a solvent or abrading the mating surfaces to improve adhesion. Accordingly, prior to application of the adhesive, the mating surfaces  18   a  to  18   n  may be cleaned and/or abraded. 
         [0050]    At step  118 , the next wall section  10  is positioned. For example, the extensions  12  and depressions  14  of the next wall section  10  may be aligned with the extensions  12  and depressions  14  of the first (or previous) wall section  10 . Once aligned, the next wall section may be urged against the previously secured wall section. Preferably, the next wall section  10  is urged against the previous wall section until an interface between the two wall sections  10  is not noticeable. 
         [0051]    At step  120 , it is determined if the wall  70  is complete. For example, the plan or design may be reviewed to determine if all wall sections  10  have been placed. In another example, the final wall section  10  generally includes the end wall section  72 . The end wall section may be configured to mate to another wall section on only one side. Therefore, if the end wall section  72  is affixed to a secured wall section  10 , the wall  70  may be complete. If it is determined that the wall  70  is not complete, the wall section positioned at step  118  may be fixed in portion at step  114 . 
         [0052]    Following completion of the wall  70 , the wall  70  may be cleaned, colored, caulked, etc. In a particular example, caulking may be applied to the joints and sand or other textured substrate may be applied to the uncured caulk. Any suitable paint or colorant may be applied to the sanded joints. Examples of suitable paint include urethane based paints. Specific examples of suitable urethane based paints include Polane® S Plus and other products manufactured by The Sherwin-Williams Company of Cleveland, Ohio, U.S.A. In addition, the sod  90  may be replaced along the edges of the wall  70  and the area may be cleared of debris. 
         [0053]    Of note, while the wall  70  is suitable for free standing wall installation, embodiments of the invention are not limited to free standing wall application. Instead, the wall  70  is suitable for retaining wall installations as well as fee standing walls. In this regard, to install the wall  70  as a retaining wall, soil from a slope, hill, or the like may be removed as appropriate to clear an area for preparing the base as described at step  102 . The wall  70  may be installed as described at step  104  and the wall  70  may be back filled to generate an embankment or retaining wall. At step  114 , additional rods such as the rod  80  may be installed and/or the length of the rod  80  may be increased in accordance with anticipated loading of the retaining wall. The back filling operations may include the application of a drainage media such as gravel and/or perforated pipe. In addition, a builder&#39;s felt or other such permeable membrane may be applied during back filling. 
         [0054]      FIG. 7  is a perspective view of a male end  130  and female end  132  suitable for use with another embodiment of the invention. As shown in  FIG. 7  the male end  130  and female end  132  are configured to mate to form a joint. The male end  130  and female end  132  facilitate alignment of the wall sections  10 . In addition, the male end  130  and female end  132  provide a variety of mating surfaces  18   a  to  18   n  to stabilize the joint between the wall sections  10  and to provide gluing surfaces. 
         [0055]    Also shown in  FIG. 7 , the wall sections  10  may optionally include a base flange  134  to provide a broader base for the wall section  10 . If included, the rod  80  (shown in  FIG. 5 ) may be driven trough the base flange  134  to facilitate anchoring the wall section  10  to the ground. 
         [0056]    In various embodiments the wall section  10  may include an integral or separate cap  136 . If the cap  136  is fabricated as a separate piece, the wall section  10  may include a tongue  138  and the cap  136  may include a corresponding groove  140 . If included, the tongue  138  and groove  140  facilitate aligning the components during assembly. 
         [0057]    Optionally, the wall  70  includes one or more cover stones  142  to cover any joint lines between the male end  130  and female end  132 . If the cover stones  142  are included, the wall section  10  may include a recess  144  to receive the cover stones  142 . 
         [0058]      FIG. 8  is a perspective view of an assembled male/female joint in accordance with  FIG. 7 . During assembly, the wall sections  10  are aligned, the adhesive  86  (shown in  FIG. 5 ) may be applied to the male end  130  and female end  132 , and the wall sections  10  may be slid together. Thereafter, the adhesive  86  may be applied to the tongue  138  and recess  144  and the cap  136  and cover stones  142  may be applied to the wall sections  10 . 
         [0059]    Also shown in  FIG. 8 , the rod  80  may be driven through the tongue  136  or top of the wall section  10 , down through the wall section  10  and into the ground to secure the wall section  10  to the ground. Alternatively or in addition to driving the rod  80  through the tongue  136 , the rod  80  may be driven into the ground through the base flange  134   
         [0060]      FIG. 9  is a perspective view of a completed male/female joint in accordance with  FIG. 7 . As shown in  FIG. 9 , the joints and flanges of the wall sections  10  may be covered in the completed wall  70  to give a natural stone wall appearance. To complete construction, additional cover stones  142  may be affixed to unfinished end of the wall sections  10  and the base flange (shown in  FIG. 8 ) may be covered with soil and/or sod. In addition, as described herein, joint lines may be filled with a urethane-based caulk, dusted with sand, and colored with paint. 
         [0061]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Summary:
To install a wall, a placement area for a set of prefabricated wall sections is determined. The placement area includes a starting end and a terminating end. A wall section of the set of prefabricated wall sections includes a first layer of urethane foam, a second layer of urethane foam, an extension and depression to mate with a corresponding depression and extension of another wall section of the set of prefabricated wall sections, and a through bore extending from an upper face of the extension, passing through the extension and exiting a lower face of the extension. During installation, surface vegetation is removed from the placement area in response to surface vegetation being present on the placement area, the soil is compacted in the placement area, and a first wall section of the set of prefabricated wall sections is placed at the starting end. In addition, the first wall section is secured to the starting end, a next wall section of the set of prefabricated wall sections is placed at the placement area, and the next wall section is affixed to a previously secured wall section of the set of prefabricated wall sections. Furthermore, the next wall section is secured to the placement area, the steps of placing, affixing, and securing next wall section are continued until the terminating end is reached. Moreover, a last wall section of the set of prefabricated wall sections is placed at the terminating end and the last wall section is affixed to the previously secured wall section.