Several factors influence the installation of TPO over modified bitumen in asphalt or bitumen modification systems. Key considerations include the compatibility of materials, surface preparation, and adhesion properties. Proper cleaning and priming of the modified bitumen surface are essential to ensure a strong bond. Additionally, environmental conditions, such as temperature and humidity, can affect the installation process. Lastly, the specific requirements of the roofing system and local building codes must also be taken into account.