Every dry vent must rise vertically to a minimum of how many inches above the flood level rim of the highest trap being vented?

A dry vent must rise vertically to a minimum of 6 inches above the flood level rim of the highest trap being vented. This requirement is in place to ensure that the vent pipe is adequately positioned to effectively ventilate the drainage system. By maintaining this height above the flood level rim, the system helps to prevent sewer gases from entering habitable spaces and ensures that water can drain properly without obstruction.

The specified height also serves to maintain a necessary air gap that is crucial for balancing pressure within the venting system, thus allowing for proper drainage and minimizing the risk of siphoning that can occur if the water level rises in a trap. This standard is designed to protect both the integrity of the plumbing system and the health and safety of the occupants in the building.