Relief vents are necessary on sanitary stacks that exceed how many floors?

Relief vents are crucial for maintaining the proper functioning of sanitary stacks, particularly as the height of the stack increases. When sanitary stacks extend beyond a certain number of floors, typically more than 10, the potential for negative pressure and siphoning increases, which could compromise the drainage system's effectiveness. Installing relief vents allows air to enter the system, which helps to equalize pressure and allows wastewater to flow smoothly through the pipes.

The specific threshold of 10 floors is set within the Massachusetts Plumbing Code due to the unique challenges presented by taller buildings, such as the increased risk of air blockage and the potential for odor issues if the drainage system is not properly ventilated. Therefore, relief vents become necessary above this height to ensure that the plumbing system operates safely and efficiently. Adhering to this guideline helps to prevent system failures and maintain the overall health of building plumbing.