The space that can be improved to get a better prediction bridging the gap between simulation and reality, and its reactions on design revision to increase the fire-resistance of a façade product before a formal test is the issue of this thesis. Regulations and design principles concerning a fire-resistant façade have been studies. With the technical support from Scheldebouw company, a running project was able to be taken as a case study, which is the main tool to look for the answers in this research. Calculation models with VOLTRA had been designed for this project and been compared with pre-test results to find out the link with reality and the limitation of simulation. An experiment on a simple model was made and analyzed with the help of TU Delft to get more information about a good prediction by simulation. Then via illustrating the revision steps based on the estimation of each phase, an economically and efficiently meliorated fire-resistant design procedure generated. Finally the thesis ended with evoking a space for the architects to rethink about the decisions made at an early stage.