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CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a completion application of co-pending U.S. Provisional Patent Application Ser. No. 60/566,673, filed Apr. 30, 2004, the entire disclosure of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to an enclosed structure that may be attached to the exterior wall of an existing or new building, such structure typically being referred to as a patio enclosure, sunroom, or solarium. More particularly, the invention relates to a patio enclosure having a high proportion of windows and a roof and constructed from a framework of composite members and insulating wall panels. Even more particularly, this invention relates to composite plastic members extruded from material having improved thermal characteristics and stability.  
         [0004]     2. Description of Prior Art  
         [0005]     Patio enclosures and sunrooms are not new to the building industry. When adding onto or remodeling an existing home or other structure, many people turn to the patio enclosure or sunroom. Such rooms are relatively easy for trained technicians to construct and are inexpensive when compared to other improvements that can be made to a home, such as remodeled bathrooms or kitchens. These enclosures have traditionally been constructed of an aluminum frame with windows or glass sections. Aluminum sunrooms are shaped with vertical walls that have a curved transition to the roof, although most may have a marquee roof or gable type roof.  
         [0006]     The following U.S. Patents and Patent Publication illustrate various enclosures, non-metallic structural elements used in constructing these enclosures, and the materials used in forming the non-metallic structural elements: Nos. 5,497,594 to Guiseppe et al.; 5,848,512 to Conn; 6,003,279 to Schneider; 6,015,611 to Deaner et al.; 6,117,924 to Brandt; 6,248,813 to Zehner; 6,412,227 to DeZen; 6,337,138 and 6,344,504 to Zehner et al.; 6,460,309 to Schneider; and 2002/0066248 to Buhrts et al.  
         [0007]     As discussed in Schneider U.S. Pat. No. 6,003,279 and U.S. Pat. No. 6,460,309, aluminum framed enclosures have several disadvantages. The main problem is poor thermal efficiency. Due to the high rate at which aluminum conducts heat, a room constructed from aluminum cannot stay comfortably cool in the summer, without air conditioning, or warm in the winter, without supplemental heating. This drawback results in dramatically increased cooling and heating costs. Further, a high rate of heat transfer can lead to condensation on the interior surfaces of the aluminum structures. Moreover, many of the windows in aluminum frame type sunrooms are generally installed in such a way that the windows cannot be opened and no screens are present.  
         [0008]     Another disadvantage is high maintenance. Aluminum must be painted if chipped and is easily dented. Construction of aluminum rooms is a major disadvantage as well. Because of the nature of the metal, the aluminum pieces must be assembled with external fasteners. External fasteners increase the time of assembly and degrade the overall aesthetics of the room.  
         [0009]     In light of these various deficiencies, Schneider U.S. Pat. No. 6,003,279 discloses various structural members, which include reinforced and non-reinforced polyvinyl chloride extrusions, which are joined together at joints using hardware which cannot be seen from inside or outside the enclosure, thereby enhancing the aesthetic appeal of the enclosure. Further, Conn U.S. Pat. No. 5,848,512 and Schneider U.S. Pat. No. 6,460,309 disclose an I-beam that is extruded from plastic and configured such that the vertical spacer wall defines a central passageway that extends between the opposite ends of the beam. Schneider U.S. Pat. No. 6,460,309 is directed to a vinyl roofing system utilizing the channel beam to interconnect roof panels with a roof cap.  
         [0010]     In obviating certain of the problems associated with unwanted condensation and thermal conductivity, many framing enclosure designs have used a “sleeve” approach wherein the aluminum elements and sections are enclosed within PVC frames. A drawback to this approach is that the aluminum reinforcing still has to be properly insulated from the rest of the vinyl profile. This approach results in massive, bulky sections with high material costs.  
         [0011]     A need continues for a low maintenance sunroom/patio enclosure that is economical, has improved thermal efficiency and minimizes thermal condensation arising from thermal transmittance, provides sliding or double hung windows and/or doorway, has an aesthetic appearance, conceals connecting fasteners, and employs fastening components that are easy to use when erecting the enclosure.  
         [0012]     Accordingly, a primary object of this invention is the provision of a sunroom/patio enclosure that obtains the benefits of framing elements and sections of polymeric and like material, and achieves the above noted needs.  
         [0013]     Another object of this invention is the provision of a sunroom/patio enclosure using frame elements formed of composite PVC to allow parts to have smaller cross-sections without a great degree of internal reinforcing.  
         [0014]     As is known, steel has much lower conductivity to thermal loss than aluminum, and has higher strength properties with lower cost.  
         [0015]     Accordingly, another object of this invention is the elimination of most if not all aluminum components from the enclosure product, such as by replacing some frame connecting elements with galvanized steel.  
         [0016]     Another object of this invention is the provision of an enclosure structure that shows no screw heads on the inside or the outside of the enclosure room.  
         [0017]     A further object of this invention is the provision of an enclosure structure comprised of composite PVC to combine the properties of wood with the maintenance free advantages of vinyl.  
       SUMMARY OF THE INVENTION  
       [0018]     Briefly described the objects of the present invention are achieved, in a room structure for attachment to the exterior wall of a building mounted on a foundation adjacent to said exterior wall, said room structure comprising an upright frame assembly having an upper end and formed by at least one enclosure wall and a roof structure extending between said exterior wall and the upper end of said frame assembly, said frame assembly including at least one vertically disposed support member, the improvement wherein 
        said support member comprises an assembly of an H-beam and a closure member,     each said support member and H-beam being comprised of a single piece of composite and having a like vertical height,     said H-beam being formed by a spacer wall and a pair of webs, the spacer wall extending between the webs and disposed inwardly and between the outer edges of the webs wherein to form a pair of outwardly open squared-C channels, and     said closure member being formed by a pair of sidewalls and a base wall, the sidewalls extending from opposite edges of the base wall wherein to form a squared-C cross-section, the closure member being snap-fittable in a friction fit into one of the squared-C channels of the H-beam to substantially close said channel and in a manner that the exterior base wall of the closure member and the edges of webs of the squared-C channel into which interfitted are substantially coplanar.        
 
         [0023]     According to an important aspect, the H-shaped beam and C-shaped closure member are extruded from a composite PVC plastic.  
         [0024]     A preferred embodiment according to this invention is the provision of a beam structure for a patio enclosure, the beam structure comprising 
        a support member and a filler member, said members extending longitudinally and each of a generally constant cross-sectional shape,     said support member having a base wall, first and second walls disposed generally perpendicularly to the plane of said base wall, and outer end faces disposed parallel to the plane of said base wall, the first and second walls cooperating to define an outwardly open longitudinally extending channel sized to receive said filler member, and     said filler member having a base member and a pair of upstanding sidewalls adapted to frictionally engage and form a snug snap-fit engagement with a respective of said first and second walls, the base member and the outer end faces forming a generally continuous surface following said interfitment.        
 
         [0028]     According to an aspect of this embodiment, the support member comprises a generally H-shaped beam member and the channel thereof has a squared-C cross-section, the filler member has a squared-C cross-section, and the H-shaped beam member and filler member are extruded, or injection molded from a synthetic wood composition.  
         [0029]     According to another aspect of this invention, the H-shaped beam member has a pair of flange members, each forming a respective of said outer end faces, and the exterior surfaces of the outer end faces and the exterior surface of the filler member are clad with vinyl cap stock.  
         [0030]     Another preferred embodiment according to this invention is the provision of modular wall for a patio enclosure formed as an add-on extension to an existing structure supported on the ground and having framing structure for at least one of a window or door, the modular wall comprising: 
        a longitudinally extending upper and lower track beam, the lower track beam being supported on the ground,     a pair of vertically extending corner posts, each post having an upper and lower end portion and forming at least one outwardly open channel,     at least one vertically extending H-beam disposed between the posts and defining a pair of separated wall sections, the H-beam having an upper and lower end portion and forming a pair of opposed outwardly open channels,     said wall section including a lower and an upper C-shaped cross-beam, a lower and an upper wall panel, and the framing structure sandwiched between said wall panels, said cross-beam having opposite longitudinal ends, a base having an outer surface, and an outwardly open channel, said lower and upper wall panel having, respectively, upper and lower edges engaged with the outer surface of a respective cross-beam, lower and upper edges interfitted within the channel of said lower and upper track beam, and vertically disposed side edges interfitted within the channels of said corner posts and H-beam,     first means for positioning and securing the lower end portions to the lower track beam and the upper end portions to the upper track beam, wherein said track beams are disposed in generally parallel horizontal relation, said corner posts are secured and positioned at the opposite longitudinal ends of the lower track beam, and the channels of said H-beam and said corner posts are facing one another,     second means for enclosing the outwardly open channels of said corner posts and said H-beam wherein to cover said first means, at least in part, and     third means for positioning and securing the opposite ends of the cross-beams to said corner post and H-beam.        
 
         [0038]     According this embodiment of the invention, the second means comprises a filler beam of predetermined cross-section, which filler beam is frictionally interfit in a snug-fit into the respective channel to form an exterior surface that appears to be unitary.  
         [0039]     Further, and according to an important aspect of this embodiment, the upper and lower track beams, the corner posts, the H-beam, the cross-beams, and the filler beam are extruded or injection molded from a synthetic wood PVC composition and have exterior surfaces selectively clad with vinyl cap stock.  
         [0040]     Another preferred embodiment according to this invention is the provision of a wall joint for a patio enclosure, which enclosure is formed as an add-on extension to an existing structure, supported on the ground, and has framing structure for at least one of a window or door, the wall joint comprising: 
        a first pair of longitudinally extending upper and lower track beams and a second pair of longitudinally extending upper and lower track beams, the first pair of track beams being disposed at a right angle to the second pair of track beams and each said lower track beam being supported on the ground,     a vertically extending corner post, said post having a lower and upper end portion and forming outwardly open first and second channels, the channels being disposed at right angles to one another,     a vertically extending first and second wall section, each said wall section including upper and lower end portions that are juxtaposable with and extend along a respective pair of said lower and upper track beams, said first wall section having a first vertical edge that is juxtaposable with the first channel of said corner post and at least one framing structure, and said second wall section having a second vertical edge that is juxtaposable with the second channel of said corner post and at least one framing structure,     first means for securing and positioning the lower end portion of said corner post and said lower track beams to said support wherein the first and second channels are juxtaposed with the ends of the lower track beams,     second means for securing and positioning the upper end portion of said corner post to said upper track beams,     third means for enclosing the outwardly open first and second channels of said corner post wherein to cover each said first and second means, at least in part, and     fourth means for connecting the wall sections to the track beams and said corner post.        
 
         [0048]     Another preferred embodiment according to this invention is the provision of a new and improved extruded article, said article produced by extruding a cellulosic inorganic filled plastic composite, the composite consisting of a bound together mixture of polyvinyl chloride, a cellulosic material, selected from sawdust, finely pulverized dried wood, and wood flour, baking flour, and a binder.  
         [0049]     A further preferred embodiment according to this invention comprises a kit for constructing an enclosure to the exterior wall of an existing structure, said kit comprising: 
        a plurality of wall panels of predetermined height, width, and thickness,     framing structure, such as for providing at least one window or door, as required,     a plurality of elongated track beams, the track beams forming upper and lower end caps of front and side walls formed by the kit and each having a central track,     a plurality of vertical uprights of H-shaped cross section, the H-beam forming two opposed outwardly opening C-shaped channels,     a plurality of C-shaped cross-beams, the cross-beam having an outwardly open C-shaped channel,     a plurality of corner posts of generally square cross section and forming two outwardly opening channels of squared-C cross-section,     means for positioning and securing the wall panels, framing structure, track beams, H-beams, C-shaped cross-beams, and corner posts to one another and the support structure, and     a plurality of closure members of squared-C cross-section, the closure members being snap-fittable into a respective C-shaped channel provided in the H-beam and corner post, wherein to close the channel and form a unitary appearing exterior.        
 
         [0058]     Preferably, and according to this embodiment of the invention the track beams, H-beam, corner-post, C-shaped cross-beam, and closure members of the kit are extruded or injection molded of a composite PVC, with predetermined exterior surfaces of each clad with a protective surface of vinyl.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0059]     These and other objects, advantages and features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, which illustrate specific embodiments of the invention. In the drawings:  
         [0060]      FIG. 1  is an exploded perspective view of a patio enclosure positioned for assembly using a variety of frame members and structural elements according to this invention;  
         [0061]      FIGS. 1A-1E  are cross-sectional views of structural elements used in assembling the enclosure of  FIG. 1 ;  
         [0062]      FIG. 2  is an elevation view showing the front side of the patio enclosure of  FIG. 1 , following assembly to an exterior wall of a house;  
         [0063]      FIG. 3  is an elevation view showing the left side of the patio enclosure of  FIG. 2 ;  
         [0064]      FIG. 4  is an elevation view showing the right side of the patio enclosure of  FIG. 2 ;  
         [0065]      FIG. 5  is a section view of the front wall taken along line  5 - 5  of  FIG. 2  showing an H-beam disposed vertically, C-shaped upper and lower track members disposed horizontally, L-shaped flanges securing the opposite ends of the beam to the track members, and connections that extend along the top and bottom ends of the front wall of the enclosure and connect the upper track member to the lower front end of the roof structure and the lower track member to the ground structure;  
         [0066]      FIG. 6  is a section view of the front wall taken along line  6 - 6  of  FIG. 2  showing a C-shaped channel member disposed horizontally, the bottom edge of a window channel supported on the channel member, the upper and lower edges of a front wall panel received in the channel member and lower track member, and a connection, which extends along and connects the front wall of the enclosure to the ground structure;  
         [0067]      FIG. 7  is a section view of the front wall taken along line  7 - 7  of  FIG. 2  showing the upper track member, the top edge of the window channel supporting a channel member, the upper and lower edges of a the front wall panel received in the upper track member and the channel member, and a the connection between the upper track member and the roof structure;  
         [0068]      FIG. 8  is a section view of the right side wall taken along line  8 - 8  of  FIG. 4  showing a channel member, the top edge of a window channel supporting the channel member, the upper and lower edges of a right side wall panel received in the upper and channel members, and a connection between the upper track member and the roof structure, which extends along and between the lower front and upper rearward end of the roof structure of the enclosure;  
         [0069]      FIG. 9  is a section view of the front wall taken along line  9 - 9  of  FIG. 2  showing two window channels separated by an H-beam, and a pair of L-shaped flanges and a pair of E-shaped filler channels interfitted into oppositely facing outwardly open channels of the H-beam, the flanges for connecting the H-beam to the a track member, and thus to the ground structure;  
         [0070]      FIG. 10  is a section view of the front wall taken along line  10 - 10  of  FIG. 2  showing opposite edges of front wall panels and an L-shaped flange for connecting the beam to the ground structure interfitted into oppositely facing outwardly open channels of the H-beam;  
         [0071]      FIG. 11  is a section view of the right side wall taken along line  11 - 11  of  FIG. 4  showing a C-shaped track member connected to the exterior wall, a window channel, and an E-shaped filler and an L-shaped flange interfitted into an outwardly open channel of the track member;  
         [0072]      FIG. 12  is a section view of the right side wall taken along line  12 - 12  of  FIG. 4  showing a track member disposed vertically and connected to the exterior wall and a vertical edge portion of an enclosure panel interfitted into the track member;  
         [0073]      FIG. 13  is a section view of the left side wall taken along line  13 - 13  of  FIG. 3  showing a C-shaped track member disposed vertically and connected to the exterior wall, a C-shaped track disposed vertically and connected by an L-shaped flange to the lower track, and thus to the ground structure, and a wall panel having opposite vertical edges interfitted into opposed channels of the track members; and  
         [0074]      FIG. 14  is a section view taken along line  14 - 14  of  FIG. 3  showing a box-shaped corner post having opposed channels for connecting the left and front wall panels to one another, and L-shaped flanges for connecting the corner post to a track member of the enclosure. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0075]     Referring to  FIGS. 1 and 2 - 4  there is shown an exemplary patio enclosure, generally indicated at  10 , constructed according to the present invention. The enclosure  10  is supported from below by a load-bearing substrate  12  and laterally by the exterior wall  14  of an existing structure, such as a house (not shown). The load bearing substrate  12  may be a concrete slab, wood decking, or the like.  
         [0076]     As shown in  FIG. 1 , the enclosure  10  comprises a front wall  16 , a pair of lateral side walls  18  and  20 , and a sloping roof  22 . The walls  16 ,  18  and  20  project upwardly from the substrate  12  where they are joined to the roof  22 . The sidewalls  18  and  20  have opposite lateral ends connected, respectively, to the house and a respective lateral end of the front wall  16 .  
         [0077]     The walls and roof of the enclosure  10  are formed by a framework of joined horizontal and vertical structural members, such as structural filler wall panels  24  and roof panels  26 , multiple pairs of sliding glass windows  28 , framed screens  30  for each pair of windows (one shown), and an optional conventional door assembly  32 .  
         [0078]     Each wall panel  24  is generally rectangularly shaped and has a central body  24   a  of polymeric material, such as foam, and outer layers  24   b  and  24   c  wherein to provide a wall panel element of generally uniform thickness. The thickness of the wall panel  24  is such that the lateral edges thereof may be interfitted into the squared-C channel of a structural element according to this invention (described in detail below). Preferably, both of the layers  24   b  and  24   c  are clad with vinyl.  
         [0079]     Preferably and according to this invention, certain of the structural elements used in this assembly are shown and identified on  FIGS. 1A-1E . These structural elements include a corner post  34 , a post or H-beam  36 , a base track  38 , a cross-beam channel  40 , and a filler  44 . As will be discussed below, nails, screws and like threaded fasteners, flanges and like connecting elements are used to connect the structural elements together and form modular wall portions and the patio enclosure  10 .  
         [0080]     Preferably and according to this invention, each of these structural elements are comprised of a composite PVC material and extruded into the desired cross-section and length. Subsequent to extrusion, a vinyl surface is clad to the exterior surfaces of the structural elements. The resulting element is sometimes referred to a composite PVC element. The structural elements made from the composite PVC material are generally stronger than wood, metal, or vinyl, has no adverse heat conduction, and has the durability of vinyl. Although extrusion is a preferable method, these elements may be injection molded.  
         [0081]     According to one aspect, the composite material is comprised of a bound together mixture of cellulosic material (esp. sawdust or like finely pulverized dried wood, such as wood flour) and baking flour (e.g., the fine powdery foodstuff obtained by grinding and sifting the meal of a grain, especially wheat, used chiefly in baking). Suitable woods for sawdust are resin-free softwoods such as pine, fir and spruce, and to a lesser extent, hardwoods. The percentage of sawdust to baking flour, measured by weight or volume, and a binder and/or mixer ingredient used to hold the composition together is determined, in part, on a cross-section property of the structural element that is desired (i.e., thickness and area moment of inertia of the cross-section).  
         [0082]     Referring to  FIG. 1A , the corner post  34  is box-like, in cross-section, axially elongated, and formed by walls  46 ,  48 ,  50  and  52 . The walls intersect with one another to form a square central opening  54  and outwardly open squared-C shaped channels  56  and  58  for receiving the lateral edge of a wall panel  24 . The walls  46  and  52  form an exterior corner with the outwardly facing surfaces  46   a  and  52   a  thereof clad with vinyl.  
         [0083]     Referring to  FIG. 1B , the post or H-beam  36  is axially elongated and includes a central body  60  and a pair of transverse flanges  62  and  64 , which define oppositely facing squared-C shaped channels  63  and  65 . The exterior surfaces  62   a  and  64   a  of the flanges  62  and  64  are clad with vinyl and the central body  60  is hollow and defines a central rectangular-shaped passageway  66 .  
         [0084]     Referring to  FIG. 1C , the base track  38  is axially extending and includes a flat base member  68  having opposite lateral edges  68   a  and  68   b  and a pair of opposed L-shaped arms  70  and  72 , the arms being spaced apart and defining a track  73  therebetween. The L-shaped arms  70  and  72  are generally perpendicular to the plane of the base member  68  and define opposed squared-C shaped channels  70   a  and  72   a  that are in faced relation and communicate with the central track  73 . The arm  70  extends along and upstands from the lateral edge  68   a  of the base member  68 . The arm  72  extends along and upstands from the base member  68  at a location inwardly of the lateral edge  68   b  of the base member  68  wherein to define an offset base portion  69 . The exterior surfaces  70   b,    72   b,  and  69   a,  respectively, of the upstanding arms  70  and  72  and the offset base portion  69  are clad with vinyl.  
         [0085]     Referring to  FIG. 1D , the cross-beam channel  40  is axially extending and forms a generally squared-C shape in cross-section. The channel  40  includes a base member  76  and a pair of opposed upstanding legs  78  wherein to define a squared-C shaped channel  80  having a width adapted to receive the lateral edge of a wall panel  24  interfitted therewithin. The base member  76  is hollow and defines a central rectangular shaped passageway  77 . The exterior surface  76   a  and  78   a,  respectively, of the base member  76  and the legs  78  are clad with vinyl.  
         [0086]     Referring to  FIG. 1E , the filler  44  is axially extending and generally E-shaped in cross-section. The filler  44  includes a flat base  82  and three upstanding legs  84 ,  86 , and  88 , the legs  84  and  88  being outer legs and upstanding from the opposite respective lateral edges of the filler, and the leg  86  being a central leg upstanding from a central location of the base  82 . The legs  84  and  86 , and the legs  86  and  88 , respectively, cooperate to form two squared-C shaped channels  85  and  87 . The exterior surface  82   a  of the central base member  80  is clad with vinyl.  
         [0087]     As shown in  FIGS. 1 and 2 - 4 , the front, left, and right walls  16 ,  18  and  20  of the enclosure  10  are assembled by he formed by various of the structural elements  36 ,  38 ,  40 ,  42 , and  44  and wall panels  24 . As shown in  FIG. 2 , the front wall  16  is defined by and extends between two box-beams  34  and includes two H-beams  36  wherein to define three modular wall portions, each portion including a window framing  28  and wall panels  16 . As shown in  FIGS. 3 and 4 , the left and right side walls  18  and  20  are defined by and extend between a box beam  34  and a base track  38 . The right side wall  20  includes an H-beam  36  and defines two modular wall portions and the left side wall  18  includes optional door framing  32 .  
         [0088]     As shown in  FIG. 5 , the modular wall portion of the front wall  16  includes elongated lower and upper base tracks  38 , denoted as  38   a  and  38   b  and disposed horizontally, and an H-beam  36  disposed vertically. L-shaped flanges  90  are secured at predetermined locations along the lower and upper base tracks  38   a  and  38   b  and serve to properly space and position the H-beams  36  and the corner box-beams  34  in a manner to receive wall panels  24 , or door or window framing  28  and  32 .  
         [0089]     The lower base track  38   a  is positioned atop the substrate  12  and secured thereto by an L-shaped flange  90  and at least one threaded fastener  92 . The flange  90  has opposite legs  90   a  and  90   b  and is nested in the track  73  formed between the opposed L-shaped arms  70  and  72  of the base member  68  with the flange leg  90   a  seated atop the base member  68  of the base track  38   a  and the flange leg  90   b  extending vertically upwardly from the base track. Fasteners  92  extend through the flange leg  90   a,  the base member  68 , and into the substrate  12 .  
         [0090]     The upper track  38   b  forms the upward vertical extension of the front wall  24  and is secured, at least in part, to the upward vertical extension of the H-beam  36 . As with the track  38   a,  the upper track  38   b  is provided with positioning flanges  90 .  
         [0091]     The lower and upper ends  36   a  and  36   b  of the H-beam  36  are nested into a respective track  73  formed between the opposed L-shaped arms of each respective track  38   a  and  38   b.  So positioned by the flanges  90  secured to the lower and upper tracks  38   a  and  38   b,  the flange leg  90   b  extending upwardly from the lower track  38   a  is threadably secured to the lower end portion of the H-beam, and the flange leg  90   b  extending downwardly from the upper track  38   b  is threadably secured to the upper end portion of the H-beam.  
         [0092]     A wall panel  24  is inserted downwardly into the opposed squared-C channels of successive H-beams  36  or corner post  34  and H-beam  36 . As can be seen in  FIG. 5 , the protective outer layers  24   b  and  24   c  of the panel  24  are generally coextensive (i.e., flush) with the outward extension of the flanges  62  and  64  of the H-beam  36 .  
         [0093]     The upper track  38   b  forms a closure cap and support for a forward lower front end of the roof structure  22 . To provide support and sealing, an axially elongated, generally cylindrical strand  94  of elastomeric material is supported atop the upper track  38   b,  on the extended base portion  74  thereof, and supports and moisture seals the roof structure  22  of the enclosure  10 .  
         [0094]     As shown in  FIG. 6 , a cross-beam channel  40  is interfitted onto and supported atop the upper lateral horizontally extending edge of the wall panel  24 . Further, window framing  28  is thereafter supported atop the cross-beam channel  40 .  
         [0095]     As shown in  FIG. 7 , a cross-beam channel  40  is interfitted onto the lower lateral horizontally extending edge of the wall panel  24 . Further, window framing  28  is thereafter abutted against the cross-beam channel  40 . In a manner described in connection with  FIG. 5 , the upper track  38   b  and strand  94  are shown in relation to the roof structure  22 .  
         [0096]     As shown in  FIG. 8 , the upper track  38   b  of the right wall  20  is shown supporting the roof structure  22 . The right wall  22  includes an upper track  38   b,  a wall panel  24 , and window framing  28 . Because the upper end of the right wall  20  angles upwardly and is supporting relation with the bottom surface of the roof structure  22 , the support strand  94  is not needed. Further, the base portion  74  extends in a direction outwardly of the enclosure  10 .  
         [0097]     As shown in  FIG. 9 , an H-beam  36  is shown separating two window framing sections  28 , and L-shaped flanges  90  are connected to opposite sides of the central body  60  extending between the flanges  62  and  64  of the H-beam. Importantly, an E-shaped filler  44  is inserted into each of the two opposed squared-C channels  63  and  65  of the H-beam.  
         [0098]     According to this invention, the cross-sections of the filler  44  and the squared-C channels  63  and  65  of the H-beam are such that the filler  44  forms, with the flanges and channels of the H-beam, a closure that makes the beam and filler elements appear as one unitary structure. That is, the base surface  82   a  of the filler  44  and the surfaces formed by the lateral edges of the respective flanges  62  and  64  are substantially coextensive with one another. The interfitment between the outer legs  84  and  88  of the filler  44  and the interior facing walls of the flanges  62  and  64  results in a snug frictional snap-fit interengegement.  
         [0099]     As shown in  FIG. 10 , the opposed squared-C channels  63  and  65  of an H-beam  36  are shown receiving opposite respective lateral vertical edges of a respective pair of panels  24 , and a flange  90  positioning the H-beam  36 .  
         [0100]     As shown in  FIG. 11 , a track  38  is disposed vertically and connected to the existing structure  14 , and window framing  28  of the left side wall  18  is shown relative to the track.  
         [0101]     Further and according to this invention, the cross-sections of a filler  44  and the central track  73  of a base track  38  are such that the filler  44  forms, with the central track  73 , a closure that makes the two elements appear as one unitary structure. The interfitment between the outer legs  84  and  88  of the filler  44  and the interior facing ends of the L-shaped arms  70  and  72  of the base track  38  results in a snug snap-fit frictional interengagement.  
         [0102]     As shown in  FIG. 12 , a base track  38  is threadably fastened to the exterior wall  14  and the vertical lateral edge of a wall panel  24  is interfitted within the track  73  formed between the opposed L-shaped arms  70  and  72  of the base track  38 .  
         [0103]     As shown in  FIG. 13 , a base track  38 , a wall panel  24 , and a cross-beam channel  40  extend vertically upwardly from their connection to a horizontally extending lower base track (not shown). The opposite lateral vertically disposed edges of the wall panel  24  are interfitted within the central track  73  and squared-C channel  80  formed by the vertically disposed base track  38  and cross-beam channel  40 . A flange  90  positions and secures the lower end of the cross-beam channel  40  relative to the lower base track. Further, the cross-beam channel  40  positions associated window framing  28 .  
         [0104]     As shown in  FIG. 14 , a corner post  34  connects the vertical edges of the left and front walls  18  and  20 . The corner post  34  extends vertically upwardly from the substrate  12  and is connected to two base tracks  38   a,  the base tracks extending horizontally along the substrate and at right angles to one another. The two base tracks  38   a  are connected to the substrate  12  by L-shaped flanges  90  in a manner described above. One L-shaped flange  90  is disposed in one base track  38   a  and has a vertical leg  90   a  received in the squared-C channel  56  and threadably fastened to the wall  48  of the corner post beam. The other L-shaped flange  90  is disposed in the other base track  38   a  and has a vertical leg  90   a  received in the squared-C channel  58  and threadably fastened to the wall  50  of the corner post beam.  
         [0105]     An E-shaped filler beam  44  is snugly interfitted within the squared-C channels  56  and  58  wherein to provide the corner post  34  with a clean aesthetic appearance.  
         [0106]     As shown in  FIG. 1 , the roof  22  is generally rectangularly shaped, angles downwardly from the exterior wall  14 , and is generally coextensive with the front and side walls  16 ,  18  and  20  of the enclosure  10 . The roof structure includes severally generally rectangularly shaped roof panels  26 , a rearward channel bracket  98 , a forward channel bracket  100 , left and right end brackets  102  and  104 , and a plurality of H-beams  36 . The roof panels  26  are as described for the wall panels  24 . Further, the channels  98  and  100  and end brackets  102  and  104  are comprised of a composite PVC, as described herein above.  
         [0107]     The rearward channel bracket  98  is mounted to the exterior wall  14  and has an outwardly open channel  98   a  adapted to receive rearward lateral edges of the roof panels  26  and rearward end portions of the H-beams  36 .  
         [0108]     The forward channel bracket  100  has an outwardly open channel  100   a  adapted to receive forward lateral edges of the roof panels  26  and forward end portions of the H-beams  36 . Further, the channel bracket  100  includes an upwardly open channel  100   b  which forms a gutter or trough for directing water from the roof  
         [0109]     The left and right end brackets  102  ands  104  have outwardly open channels  102   a  and  104   a,  respectively, for receiving the lateral edge of a roof panel  26 .  
         [0110]     As assembled, the rear channel  98  is connected to the exterior wall  14 . The rectangular roof panels  26  have their opposite longitudinal edge portions interfitted within the channel  63  and  65  of a respective H-beam  36 , or left and right end bracket  100  and  102 , and their opposite lateral edges ends interfitted within a channel  98   a  and  100   a  in the rearward and forward channel brackets  98  and  100 . The opposite ends of the channel brackets  98  and  100  are connected to the opposite ends of the left and right end brackets  102  and  104 .  
         [0111]     As contemplated herein, the patio enclosure  10  may be advantageously supplied to the user in kit form, ready to go and for assembly to an existing structure. The kit for constructing an enclosure to the exterior wall of an existing structure would generally comprise the various structural elements as described in detail herein above.  
         [0112]     In particular, the kit would comprise a plurality of wall panels  24  of predetermined height, width, and thickness, framing structure  28  and  32  for at least one window or door, a plurality of elongated track beams  38 , the track beams forming upper and lower end caps of front and side walls  16 ,  18  and  20  formed by the kit, a plurality of vertical uprights  36  of H-shaped cross section, a plurality of corner posts  34 , a plurality of C-shaped cross-beams  40 , a plurality of closure members  44  of squared-C cross-section, the closure members being snap-fittable into a respective C-shaped channel provided in the H-beam and corner post, and fasteners  90  and  92  for positioning and securing the wall panels, framing structure, track beams, H-beams, corner posts, C-shaped cross-beams, and closure members to one another and the support structure.  
         [0113]     Preferably, and according to this embodiment of the invention, the track beams, H-beam, corner-post, C-shaped cross-beam, and closure members of the kit are extruded or injection molded of a composite PVC, with predetermined exterior surfaces clad with a vinyl.

Summary:
An enclosed structure, such as a patio enclosure, sunroom, or solarium, is attachable to the exterior wall of a building, has a high proportion of windows and a roof, and constructed from a framework of composite members and insulating wall panels, the panels and wall members being extruded from material having improved thermal characteristics and stability.