One of the most common causes of disruption is a variation or change order, coming from the employer, and amending what the contractor is required to do, or what the project is required to deliver. This can occur even after work has commenced. Variations can also occur as a result of the contractors themselves however. This frequently occurs during complex projects because of the excitement that certain solutions might generate within the contractor’s own staff. For example, when a complex problem gives rise to a novel or unique solution, not infrequently will a contractor approve such a solution even though it is more costly than the solution provided for in the original plans. It is also possible that the contractor and employer have interpreted the plans differently, and so the requirement changes when the contractor becomes aware of the discrepancy and changes the plan to meet the employers interpretation.