The site of construction is considered a resource like any other resource in a project and, as such, has to be managed in order to have maximum benefit. The placement of temporary facilities on-site is a key site-layout planning task. In dynamic congested sites, the locations of temporary facilities are changed frequently due to very limited space. This research proposes a model to help in the planning of an efficient dynamic-site layout. The model consists of commercial software programs which have been integrated to offer a complete solution. The problems associated with the planning of a dynamic, congested construction site are analyzed and the influencing factors for site layout are illustrated. The Unified Modeling Language (UML) is introduced to illustrate the model’s structure, its components and the interactions among them. The UML describes the activities during the model’s implementation, where the decisions must be made, and those involved in decision making. The computer model is divided into two main sections: the first uses the special purpose simulation (Simphony) to help the planner identify the required number of temporary facilities. The second section provides the effective placement of the temporary facilities on the construction site, for which Microsoft Access maintains the information libraries for the construction site and the required temporary facilities. Fuzzy applications are developed to assess the weight parameter for the relation between the temporary facilities. The Visual Basic for Application (VBA) module is implemented to transfer construction-site information between AutoCAD, Simphony and Microsoft Access.. For optimization research, Genetic Algorithm (GA) is used to find the near-best solution for placing the temporary facilities at site where the weight between temporary facilities is used as the fitness function. The module feature in the Microsoft access is used to implement the Genetic Algorithm which facilitates the connection between the GA and Microsoft Access libraries .The final chosen solution is shown on the AutoCAD site-layout drawing. Different scenarios can be produced to allow the planner to choose the one which adopts the most requirements. The model has a highly-usable interface, with the objectives that no special training will be required.