Single-wall metal pipe must extend at least ______ above the highest point where it passes through a roof.

The requirement for single-wall metal pipe to extend at least 2 feet above the highest point where it passes through a roof is based on safety and functioning standards designed to ensure proper ventilation and to minimize the risk of fire hazards. This height helps to prevent any backdrafts of combustion gases into the dwelling while also allowing for adequate clearance from the roofline.

Moreover, raising the pipe above this minimum height can also help in mitigating the chances of water intrusion and debris accumulation near the exit point, which can obstruct the venting process. The 2-foot specification is generally recognized in various building codes and guidelines, ensuring consistency and safety in installation practices across different regions. Therefore, adhering to this standard minimizes risks associated with improper exhaust venting and enhances the efficiency of the appliance being serviced by the venting system.