This paper presents a Genetic Algorithm (GA) based optimization model for repetitive projects when considering soft logic. There have been several models developed for Time–cost Trade-Off optimization in repetitive projects and these models were set up to search for optimum output rate that yields the minimum total cost for each project. Previous researches are based on the assumption that work sequence cannot be changed for different work zones. In reality, work sequence between work zones are not fixed (actually, constantly adjusted) throughout the project. Instead, they are often changed to shorten the construction time and minimize the total cost. Scheduling with the non-fixed work sequences between work zones is known as the soft logic method. Considering the soft logic in repetitive projects, the proposed GA model aims to assist the project team to find the minimum overall cost subjecting to different output rates and logical sequences.