What is the minimum height above the flood rim at which a relief vent shall connect to the vent stack?

What is the minimum height above the flood rim at which a relief vent shall connect to the vent stack?

• A. 4 inches
• B. 6 inches
• C. 8 inches
• D. 12 inches

Answer: (B)

When drainage systems vent, the goal is to allow air to enter the system to prevent siphoning of traps and to relieve any backpressure created by flowing wastewater. A relief vent must connect to the vent stack high enough so that it cannot be flooded or submerged by water from the highest fixture it serves. That way, air can reach the vent stack freely and the venting system remains effective during discharge events. The minimum height established for this connection is six inches above the flood rim. This is the smallest height that reliably keeps the vent path clear of water, ensuring proper venting without being overly restrictive in layout. Heights greater than this still work, but six inches is the required minimum.

When drainage systems vent, the goal is to allow air to enter the system to prevent siphoning of traps and to relieve any backpressure created by flowing wastewater. A relief vent must connect to the vent stack high enough so that it cannot be flooded or submerged by water from the highest fixture it serves. That way, air can reach the vent stack freely and the venting system remains effective during discharge events.

The minimum height established for this connection is six inches above the flood rim. This is the smallest height that reliably keeps the vent path clear of water, ensuring proper venting without being overly restrictive in layout. Heights greater than this still work, but six inches is the required minimum.