Master Plumber Practice Exam 2025 – Complete Prep Guide

A drainage stack that extends ten or more stories above the building drain is required to be served by a parallel vent stack to ensure proper ventilation. This parallel vent stack aids in maintaining the pressure equilibrium within the drainage system, which is essential in preventing siphoning of water from traps and ensuring that waste flows freely without causing negative pressure that could disrupt the system. In high-rise buildings, where the vertical distance is significant, the venting becomes even more critical to manage air flow and to allow for efficient drainage at all levels.

The alternative options, while they may have specific uses in plumbing systems, do not adequately address the unique challenges posed by tall structures. For instance, cleanouts at each floor are important for maintenance but do not facilitate ventilation. Extra-heavy fittings might be used for durability in a high-rise setting but do not specifically address the need for adequate airflow. Similarly, while straps are necessary for securing pipes and preventing movement, they do not contribute to the venting requirements essential for systems exceeding ten stories. Therefore, the establishment of a parallel vent stack is the most effective solution for proper drainage and ventilation in such high-rise situations.