CSLB Class B General Contractor's License Practice Exam

How many plumbing fixtures can be vented by a single vertical wet-vent?

1. 3

2. 4

3. 5

4. It depends on the fixture units

The correct answer is: It depends on the fixture units

A single vertical wet vent can accommodate a varying number of plumbing fixtures based on the total fixture units that are calculated for the connected fixtures. Fixture units are a measure used in plumbing design to account for the anticipated demand that different fixtures will place on the drainage system. By using fixture units, plumbers can assess the overall capacity needed for a wet vent system. Each type of plumbing fixture, such as sinks, toilets, and bathtubs, has a designated fixture unit value that is defined by plumbing codes. The total of these values will determine how many fixtures can be adequately vented through a single wet vent. Moreover, local building codes may impose specific requirements or limitations on the maximum number of fixtures allowed per wet vent, emphasizing the importance of fixture unit calculations. This ensures that the venting system performs effectively for the specific configuration and usage of the fixtures involved. If a generic limit were suggested, it would not account for different fixture types, their usage, or variations in design standards, hence the answer leans on the necessity to refer to fixture units in determining the number of plumbing fixtures that can be vented by a single vertical wet vent.