The use of modular construction as opposed to traditional on-site construction presents an opportunity to improve a projects economic and sustainable performance. At the same time, substantial savings in the overall projects duration can be achieved. The potential for reducing the overall makespan period involved in manufacturing and assembling the modularised components, along with the constant need for aligning the work schedule with the in-house manufacturing schedule, leads to the need for a repetitive scheduling optimisation procedure for modular manufacturing operations. This paper presents a framework and a decision support system to schedule operations in modular building factories. The framework is divided into 3 layers; the first layer concerns the assignment of workers to workstations; the second layer solves the scheduling of jobs to workstations while the last layer governs the overall operations of production lines through formulating a parallel machine scheduling problem. For demonstration purposes, a computational test is conducted on the final optimisation stage using a practical case study to solve the parallel machine scheduling problem. To account for resource allocation and levelling, the model is presented as a resource constraint one. Results reveal the satisfactory performance of the proposed model.