wall 100 and the dimensions of the side rails 108 and vertical supports 104 determines the width of the gap 112 the wall panel 100 further includes a horizontal bridging rail 114 extending horizontally along the length of the wall panel 100 and disposed at about the midsection thereof the horizontal bridging rail 114 in the illustrated embodiment is disposed within the gap 112 and is connected to the side rails 108 and vertical supports 104 to provide stability to the wall panel during use two or more wall panels 110 may be stacked one on top of the other to build a multi story structure that can support molds or other floor ceiling slab structures vertical interconnection between adjacent wall panels 100 can be accomplished by a bolted or welded connection arrangement in the illustrated embodiment a block 116 having a hole 118 is disposed on either end of the wall panel 100 atop the ends of the top bar 106 each block 116 may be made of a section of square or rectangular tube stock and the hole 118 may be formed through the top side wall of each block 118 to accommodate a bolt therethrough not shown for connecting an additional panel 110 in a similar arrangement two angled brackets 120 may be disposed one.