The construction industry is highly vulnerable to the spread of any infectious disease due to the nature of the work environment that requires close physical proximity of workers. Other industries might mitigate this affliction by working from home to reduce any contact, which is not applicable to construction workers. Decreasing the number of crews on site would reduce the risk of spreading the infection, but would reduce productivity and delay the progress of the project. On the other hand, having many workers on site would have a higher risk for the spread of the infection and consequently, more workers would have to be quarantined, which would also impact the project’s duration. In this paper, an agent-based simulation model is developed to simulate the spread of an infectious disease among different crews in a construction project. The software used for the simulation is “AnyLogic,” which provides an agent-based simulation to replicate the interaction between workers on construction sites. The infection spreading is then simulated based on the proximity of other susceptible workers to the infected one. The rate of spreading would vary according to the distance and number of other workers nearby. The infected workers would, then, be required to quarantine and would return after the isolation period. The relation between the project duration, number of resources, and the rate of infection spreading is investigated for this model, and, therefore, would be used to optimize the duration of the project by allocating the number of crews needed that would minimize the spread of the infection. The simulation of the model showed that the project duration could be delayed up to 35% of its planned duration and the number of infections could be between 26 and 51% among the construction workers. The optimized experiment for the number of resources used has decreased the delay in completion time to 2% which indicates that project managers could reduce the impact of the disease spreading by allocating the right crew size.