Abstract: A fence unit extending between vertical posts is formed using extruded plastic top, middle and bottom rails resting on hangers attached to the posts. Each of the rails has parallel side walls as well as top and bottom walls and a pair of internal wall portions extending between the side wall portions. A reinforced member in the form of a channel extends through each of the rails between the internal wall portions. The bottom rail has the top a wall cut away to form a groove while the top rail has the bottom wall cut away to form a groove and the middle rail has both the top and bottom rails cut away in a similar manner. The assembly then includes boards or panels adapted to fit between the top and middle rails and the middle bottom rails and extending into the grooves to abut the adjacent internal wall portions and screw fasteners extend into the rail portions to hold the assembly together as a unit.