Different crews with different skill-sets work on the three production-related phases of construction: Excavation, Concrete, and Building.  These phases are very different, and each has its own queue.  Once a phase is completed, the job moves to the bottom of the queue for the next phase.  Economy Garages may start its part of the project at any phase.  If a homeowner completes the concrete, the contract will be started at the bottom of the building queue; similarly, if the homeowner completes the excavation phase, the contract starts at the bottom of the concrete queue.  The jobs remain in order within the queues but may be interrupted due to addendums, materials, payments, utility issues and/or crew availability.