Several factors influence the performance of a 3-ply modified bitumen roofing system. These include the type of polymer used for modification (such as APP or SBS), the quality of the asphalt, the application method (torch-applied, self-adhered, or cold adhesive), and environmental conditions during installation. Additionally, proper substrate preparation, drainage design, and maintenance practices play crucial roles in the system’s longevity and effectiveness against weathering, UV exposure, and thermal cycling.