A vent shall rise vertically at an angle to the vertical before offsetting horizontally. What are the required angle and the distance above the served fixture before offsetting?

A vent shall rise vertically at an angle to the vertical before offsetting horizontally. What are the required angle and the distance above the served fixture before offsetting?

• A. 30 degrees; 3 inches
• B. 45 degrees; 6 inches
• C. 60 degrees; 8 inches
• D. 90 degrees; 12 inches

Answer: (B)

The important idea here is that a vent from a fixture needs a short vertical rise before any horizontal offset so it can do its job of venting the drain system. The specific requirement is to lean away from the vertical at a 45-degree angle for a short distance, and to reach at least 6 inches above the served fixture before it starts to offset horizontally. This setup helps keep an open air path in the vent and prevents siphoning of the trap by ensuring the vent remains effective close to the fixture. If the rise is shorter than 6 inches, or the offset happens too soon, the vent may not provide adequate protection against siphon and could compromise proper venting. Angles like 30, 60, or 90 degrees and other distances (such as 3, 8, or 12 inches) don’t align with this standard requirement, which is why the 45-degree angle with a 6-inch rise is the correct choice.

The important idea here is that a vent from a fixture needs a short vertical rise before any horizontal offset so it can do its job of venting the drain system. The specific requirement is to lean away from the vertical at a 45-degree angle for a short distance, and to reach at least 6 inches above the served fixture before it starts to offset horizontally. This setup helps keep an open air path in the vent and prevents siphoning of the trap by ensuring the vent remains effective close to the fixture. If the rise is shorter than 6 inches, or the offset happens too soon, the vent may not provide adequate protection against siphon and could compromise proper venting. Angles like 30, 60, or 90 degrees and other distances (such as 3, 8, or 12 inches) don’t align with this standard requirement, which is why the 45-degree angle with a 6-inch rise is the correct choice.