Two major problems appear during the design of a framework. The first is related to synthesizing generic elements for a family of applications and connecting them to an integrated control flow. The second lies in the design of a powerful, modular, reliable architecture that is easy to (re)use and understand. The fact of including design patterns in the architecture of frameworks minimizes the second problem. Indeed, design patterns provide proven, flexible, well-engineered design solutions at a higher abstraction level than classes. Their associated documentation records information from experienced object-oriented designers about solutions to recurrent problems, about contexts in which the patterns are applicable, about forces involved and consequences related to their use. This paper presents a number of the benefits of integrating design patterns in the development of an object-oriented framework related to fuzzy logic control. It also reports on an object-oriented design for Fuzzy Knowledge Based Control (FKBC) that includes design patterns to facilitate the development, maintenance and documentation of the FKBC framework.