What is the maximum vertical distance from the fixture outlet to the trap weir?

The maximum vertical distance from the fixture outlet to the trap weir is specified to be 24 inches in plumbing codes. This distance is critical for ensuring proper drainage and preventing issues such as siphoning and backflow. If the distance exceeds this limit, the trap may not function effectively, leading to inadequate sewage flow and potential clogging. A distance of 24 inches strikes a balance between effective drainage and practical installation constraints. Using this height limit helps maintain a functioning drainage system while allowing enough vertical space for proper installation and accessibility for maintenance.