DIY & Home Improvement

As you correctly noted, the plumbing vent pipe should be venting the drain line upward through the roof. There are several common reasons for the gurgling noise you are experiencing. First, the vent pipe may be too short, or it may have been installed at an angle which is causing the pipe to fill up with water. Next, if the vent line is too low inside the pipe and water flows down the pipe, it can cause an overflow at the sink as it tries to pull the air out of the system. Finally, if you have a vent stack that is too small in diameter, it will cause the vibration you are hearing.