Abstract: A system and method for pre-assembly of interior casework components for a wall space of a dwelling unit employs a container box formed as a rigid container shell in a quadrangular shape sized to fit through a standard minimum door opening of a dwelling unit. The container shell is formed by a bottom panel, upright side panels, top panel, rear panel, and removable front cover panel joined together by fastener members. The container box is mounted on roller wheels for delivery in a dwelling unit. A plurality of casework components are pre-assembled in the container shell and are installed in place when the container box is positioned in the dwelling unit. The container box may be formed as a half-height system of upper or lower casework components, and may be combined with other container box systems modularly.