Experienced project managers know that many things can go wrong in projects, regardless of how successfully the work is planned and executed. Component or full-project failures, when they do occur, can often be traced to a poorly developed or nonexistent WBS. A poorly constructed WBS can result in adverse project outcomes including ongoing, repeated project re-plans and extensions, unclear work assignments, scope creep or unmanageable, frequently changing scope, budget overrun, missed deadlines, and unusable new products or delivered features.
The WBS is a foundational building block to initiating, planning, executing, and monitoring and controlling processes that are used to manage projects as they are described in the PMBOK® Guide—Third Edition (PMI, 2004). Typical examples of the contribution that the WBS makes to other processes are described and elaborated in the Practice Standard for Work Breakdown Structures–Second Edition (PMI, 2006).