Modularization and standardization (M&S) of MEP (mechanical, electrical, and plumbing) systems improve end customer value according to lean concepts and principles. However, the implementation of M&S is challenging. The challenges of the implementation were investigated and a guidelines model is developed, based on the executed case studies, the interviews, and literature of M&S. Suggestions to manage the implementation of M&S of MEP systems are made depending on lean concepts and tools.