used to connect the structural elements together and form modular wall portions and the patio enclosure 10 preferably and according to this invention each of the 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 as a composite pvc element the structural elements made from the composite pvc material are generally stronger than wood metal or vinyl yet they have the durability of vinyl and have no adverse heat conduction such as associated with metals although extrusion is a preferable method these elements can be injection molded according to one aspect the composite material comprises a bound together mixture of cellulosic material e g sawdust wood flour or like finely pulverized dried wood 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 referring to fig1 a 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 substantially square shaped central opening 54 and a pair.