Which vent is typically located on the top floor and is the last connection before the stack vent goes through the roof?

Which vent is typically located on the top floor and is the last connection before the stack vent goes through the roof?

• A. Riser vent
• B. Loop vent
• C. Branch vent
• D. Vent through roof

Answer: (B)

A loop vent is used to vent fixtures that are on the top floor by routing a vent line upward to that top level and tying it into the vertical vent stack right before the stack goes through the roof. This placement means it serves as the last vent connection on the top floor, ensuring air can reach the top-floor traps as the stack continues upward and exits the roof. Other vent types either run as a continuous vertical riser with the stack, vent a smaller group on a given floor, or are simply the vent that actually exits through the roof, so they don’t fit the description of the final top-floor connection before the roof.

A loop vent is used to vent fixtures that are on the top floor by routing a vent line upward to that top level and tying it into the vertical vent stack right before the stack goes through the roof. This placement means it serves as the last vent connection on the top floor, ensuring air can reach the top-floor traps as the stack continues upward and exits the roof. Other vent types either run as a continuous vertical riser with the stack, vent a smaller group on a given floor, or are simply the vent that actually exits through the roof, so they don’t fit the description of the final top-floor connection before the roof.