A chimney for residential-type gas appliances must extend how much above the highest point where it passes through a roof?

The correct answer is that a chimney for residential-type gas appliances must extend 3 feet above the highest point where it passes through a roof. This regulation is intended to ensure proper venting of exhaust gases, reducing the risk of backdraft and improving the overall efficiency of the appliance. By extending 3 feet above the roof, the chimney helps to dissipate smoke and combustion byproducts safely away from the building, minimizing the potential for these harmful gases to re-enter the living space.

In addition to maintaining proper ventilation, this height requirement takes into account factors such as the height of nearby structures, wind patterns, and the potential for snow accumulation, all of which can affect the performance of the chimney. Therefore, ensuring that it is extended adequately is critical for safety and compliance with building codes.