What is the minimum height a B vent must terminate above a roof with a 12/12 pitch?

The correct answer reflects the standard requirements for the termination height of B vent systems, specifically in relation to the pitch of the roof. When a roof has a slope of 12/12, it essentially creates a scenario where the vent needs to be elevated adequately to ensure proper venting performance and to prevent any potential backdrafting of flue gases.

According to building codes and manufacturer specifications, when dealing with a roof that has a steep pitch like 12/12, the termination height of a B vent must be at least 4 feet above the highest point of the roof within a certain horizontal distance—typically a minimum of 10-15 feet depending on the system. This height ensures that the flue gases can disperse effectively into the atmosphere and that any precipitation does not have the potential to enter the vent system, which could otherwise create safety hazards or reduce the efficiency of the venting.

In summary, that 4-foot height is critical for maintaining the safety and effectiveness of venting on steep-pitched roofs, aligning with building codes and established best practices in ventilation design.