What is a common rule regarding venting stack offsets?

The correct rule regarding venting stack offsets is that no drain connection can be within 10 feet of the bottom of the upper stack. This rule is based on ensuring that the venting system functions properly by maintaining adequate air circulation and preventing situations where wastewater can obstruct the venting system. The purpose of this distance is to avoid the risk of siphoning and to ensure that there is appropriate ventilation for the drainage system to prevent the formation of vacuum conditions that could lead to drainage failures or negative pressure.

This standard is vital for maintaining the integrity of the drain and vent systems in a plumbing design, allowing for the proper flow of air and gases which is critical to maintaining the performance of bathroom and kitchen plumbing fixtures. By adhering to this distance requirement, designers ensure that venting is effective and compliant with plumbing codes that govern drainage systems.

Other options deal with varying distances tied to connections and placement, but they do not encapsulate the common regulations on offsets as comprehensively as the correct one does.