Defective designs have been acknowledged as important risks in construction projects. For effective management of these risks, it is important to understand how and why the defects happen. Part of an ongoing research program, this paper aims to propose two navigational measures, with an emphasis on human elements, for managing defective designs. It starts with outlining a mechanism of defective designs causation based on the systems approach to human errors as the basis of the two measures. The first measure is a reactive measure, which works as an investigative tool after defective designs occurrence. It is proposed to give step-by-step guidance in the identification of primary causes of past defect events. The second measure is proactive process measure, which is intended to operate prior to occurrences of defective design. It periodically assesses influencing factors and indicates those most needing correction. A guideline for practical use of the measures is presented in the paper. At the center of the discussion, critical roles of management at higher levels are kept in mind.