d and 16 b also featured is a lower planar portion 76 which perpendicularly meets planar portions 70 and 72 as shown in fig6 which creates a flat stable base for the building system 10 notches 78 and 80 create inbound shoulders 82 and 84 outbound shoulders 86 and 88 and end portions 90 and 92 fig7 illustrates a front view of upper half height member 18 a and fig8 illustrates an end view of the lower half height member 18 a with additional reference to fig1 and fig2 the features of upper member 18 a are now described upper half height member 18 b has the same structure as lower half height member 18 a upper member 18 a are comprised of two lower beveled portions 94 and 96 which extend downwardly and inwardly from planar portions 98 and 100 and meet at a groove joint 102 groove joint 102 allows upper member 18 a to interlock with the tongue joint 30 of the intermediate members 16 d and 16 b also featured is the upper planar portion 104 which perpendicularly meets planar portions 98 and 100 as shown in fig8 which creates a flat smooth top for the building system 10 notches 106 and 108 create inbound shoulders 110 and 112 outbound shoulders 114 and 116 and end portions 118 and 120 the notches 106 and 108 in upper member 18.