Abstract: In order to separate boards of wood or the like from one another in a stack, spacing strips are successively lifted from a hopper by a rising flight conveyor and are accumulated on a generally horizontal extension of that conveyor for consecutive pickup, at predetermined instants of an operating cycle of a stacker, by a transfer mechanism delivering each strip to a passing gripper on a continuously moving transport band overlying the stack. A vertically movable frame beneath the transport band, positioned above a stacking platform, carries a series of unloaders normally projecting into the path of the oncoming strips for dislodging them from their grippers and depositing them on a board already resting on the platform as part of a growing stack. The unloaders can be selectively deactivated to vary the number and/or the spacing of the strips deposited on the top of the stack.