Since Web applications are very complex, compared to traditional client/server applications, Web application design with the UML can be obtrusively hard for a modeller. The grounds are that the UML does not define the correct semantics to be able to visualize a web application correctly. This is a qualitative reduction study where we have used interviews and our own experience during the redesign of a UML-modelled e-commerce application with WAE-UML. Using the flow of a case study we have tried to see if we can improve three quality attributes of a complete design. Stakeholder communication reflects the need of unambiguous design artefacts that are easy to understand and that mediate the real message of the use-case. The condition of the design artefacts should provide artefacts that resemble reality and that not are misleading and provide for verification and validation of the requirements. The last attribute maintainability should provide means for easy maintenance and updates. We found that WAE-UML can improve these quality attributes in a design but the impact it has on them is dependent on two major aspects. The first aspect concerns the designers’ judgment of detail in a design. A detailed design can be good considering requirements and use-case traceability and verification, but prohibit communication. Maintainability can also be improved in a detailed design because the diagrams are less abstract and a truer picture of the application. The second aspect is that it depends on the knowledge possessed of the semantics by the people in contact with the design documents. Due to the time aspect the people working in the industry that we interviewed were reluctant to modelling a Web application at all. They thought it would take a long time to learn WAE-UML but also for executing a design phase.