The Crucial Role Vent Stacks Play

In multi-story buildings such as condominiums and high-rises, the sanitary drainage system consists of three main components: horizontal underground lines, branch lines, and vertical stacks. There are various types of vertical stacks, one of which is the vent stack. The vent stack is the portion of a vertical stack that rises above the highest fixture tie-in.

Unlike soil and waste stacks, vent stacks do not carry liquids. Instead, they provide airflow through the drainage system. When water flows through branch lines and other stacks, vent stacks prevent them from being forced by back pressure, a process also referred to as “trap suckout.” In simpler terms, vent stacks use gravity to allow the free flow of water and sewage down drains.

Anatomy of Vent Stacks

A commercial building’s venting system typically consists of a number of pipes leading to the outdoors, usually through the roof. They’re designed to release sewer gases outside instead of inside the building. Vent stacks play another important role in that they introduce oxygen into the waste system. This allows for aerobic sewage digestion and deters noxious oxygen-deprived anaerobic decomposition which can produce harmful gases like methane into the environment.

Obviously, without an effective, operational venting system your building cannot have a capable and operational sewer plumbing system.