Why is the concrete limited to a placement height or lifts of 4 feet (1.2 m)?

To alleviate the pressure from the liquid concrete, the concrete is placed in layers or ‘lifts’. The first lift is limited to 4' (1.2 m) of concrete around the perimeter of the building. This allows approximately one hour for the concrete to set-up before continuing with the next 4' (1.2 m) lift. The lower lift provides support for the next lift as the concrete is placed continuously around the building in consecutive lifts to the top of the wall.