Excavation shoring is an integrated scheduling method for installing modified precast building columns, first floor grade slab and supporting beams prior to site excavation, and to use these components, together with specialized shoring panels and/or modified exterior wall panels, which are installed simultaneously with the excavation, and together with underground floor structures and beams, as a shoring system during excavation. The shoring or wall panels are forced downwardly to support the excavation sides as excavation proceeds downwards, avoiding the necessity of a conventional shoring system.