Continuous Vents In A Plumbing System

What Is A Continuous Vent?

A continuous vent is a vent which extends from a vertical soil or waste pipe and can serve one or multiple fixtures located on the same story. Continuous vents, like all plumbing vents, protect the trap seal(s) of the fixtures they serve. The most common application of continuous vents are when serving wet vented branches, as seen in the image on the right(click the image to view).

The naming terminology of continuous vents overlap with individual vents and dual vents if they are connected to a vertical soil or waste pipe, but the sizing requirements are different. If the soil or waste pipe passes through one or more stories, it becomes a Soil or Waste Stack and will be vented by a Stack Vent, not a continuous vent

Sizing Continuous Vents

There are two sizing factors that determine the size of a continuous vent, they are:

1. 1. The drainage fixture units on the soil or waste pipe they serve;
   2. The length of the vent from the connection to the vertical soil or waste pipe, to a major source of air(vent stack, stack vent or outside air).