This paper proposes a model to structure routine design problems as well as a model of its design
complexity. The idea is that having a proper model of the structure of such problems enables understanding
its complexity, and likewise, a proper understanding of its complexity enables the development of systematic
approaches to solve them. The end goal is to develop computer systems capable of taking over routine
design tasks based on generic and systematic solving approaches. It is proposed to structure routine design
in three main states: problem class, problem instance, and problem solution. Design complexity is related to
the degree of uncertainty in knowing how to move a design problem from one state to another. Axiomatic
Design Theory is used as reference for understanding complexity in routine design.