Illinois Plumbing Code Practice

In the context of the Illinois Plumbing Code, fixtures and horizontal branches should not be connected above or below an offset of a soil or waste stack within a specific vertical distance to ensure proper drainage and prevent siphoning in the system. The correct distance is 2 feet, which allows for the maintenance of proper air flow and venting within the plumbing system. This distance helps to prevent negative pressure from affecting the drainage of connected fixtures and minimizes the risk of trap seal loss.

Connecting fixtures or branches too close to an offset without a relief vent can lead to drainage issues, such as backflow or insufficient flow due to improper venting, which may undermine the performance of the plumbing system. Therefore, adhering to the 2-foot distance helps to maintain the integrity and efficiency of the plumbing installation.