When using lead as a flashing on a roof drain, the flashing shall extend at least ____________________ inches beyond the outer circumference of the stone guard clamping ring.

Using lead as flashing around a roof drain is a critical aspect of ensuring proper water drainage and preventing leaks. The Omaha Plumbing Code specifies that the flashing must extend at least 12 inches beyond the outer circumference of the stone guard clamping ring. This requirement is in place to provide adequate coverage and protection against water infiltration, which can occur if the flashing is not sufficiently extended.

By having a 12-inch extension, the flashing can effectively direct water away from the roof drain and minimize the risk of pooling or leakage that could otherwise lead to water damage. The dimensions provided in the code are determined based on factors such as the surface area needing protection, the potential for water runoff, and the need to overlap with surrounding roofing materials.

Options that indicate a greater extension, such as 18 or 24 inches, would exceed the minimum requirement and may not be necessary for effective drainage in typical scenarios, nor are they mandated by the code. Therefore, 12 inches is deemed adequate while balancing functionality and compliance with the established plumbing standards.