In commercial building construction, the flow or sequence of critical work is relatively consistent. It typically begins with excavation and foundation work, followed by the supporting or superstructure, floors and roof. Immediately following the completion of floors is the framing of interior corridors or “interference” wall framing. There are basically two types of interior wall framing: primary, corridor or interference walls; and secondary, or partition walls. The corridor or interference walls are defined as walls that must be installed, before any of the mechanical (HVAC, ductwork), main electrical conduits, plumbing, and, in most cases, fire-suppression piping (collectively referred to as MEP). Top-Down wallboard is the installation of gypsum wallboard to both sides of a partition, extending from the underside of structure, top of partition, and down to a point below any and all interfering MEP installations. The reason these walls must be installed first, including top-down gypsum wallboard, is because the MEP installations will block access to these walls, affecting life-safety of the partitions, and safety hazards for tradespersons. “Interior walls are topped out before MEPs are in place to minimize obstructions to access these hard-to-reach areas by drywall craft workers” (Source: AGC 2018 CSEA Safety Management Best Practices).
Therefore, the sequence of the installations must be: