Our study focuses on the effort needed for designing Web applications. The effort required for the design phase is an important part of the total development effort of a Web application, whose implementation can be (partially) automated by tools. We carried out an empirical study with the students of an advanced university class that used W2000, as special-purpose object-oriented design notation for the design of Web applications. We investigated the impact of a few attributes (e.g., size, complexity) of the W2000 design artifacts built during the design phase on the total effort needed to design web applications and we identified a few attributes that may be related to the total design effort. In addition, we carried out a finer-grain analysis, by studying which of these attributes have an impact on the effort devoted to the steps of the design phase that are followed when using W2000.