Abstract: A building form into which concrete may be poured to form a column or similar structure includes a plurality of stacked form units having interconnected expandable and contractable joints. The application of a vertically upward force to the joints of the uppermost form unit causes all the units to move together, first laterally outwardly and then upwardly to strip the form from the column. The form thereafter may be moved to another location where the joints of the form units may be contracted to provide a form for pouring another column. The joints include movable portions which are cammed outwardly or inwardly depending on the direction of vertical movement of a central, vertically movable portion.