At the juncture of the roof surface and a vertical surface (wall), the flashing shall NOT be less than?

Flashing at the juncture of a roof surface and a vertical wall is crucial for preventing water infiltration, and the code specifies a minimum thickness to ensure durability and resistance to the elements. The correct choice indicates that the flashing should be made of at least 26 gauge galvanized metal. Galvanization provides additional protection against corrosion, which is particularly important in roofing applications where moisture exposure is frequent.

Using 26 gauge galvanized metal as the minimum ensures that the flashing is robust enough to withstand the forces acting on it during severe weather conditions, including wind and rain. The thickness of the material is critical, as thinner gauges may not provide adequate strength or may become damaged more easily over time.

In contrast, other choices either specify thicker gauges, which may be unnecessarily robust for many applications, or thinner gauges that fail to meet the necessary requirements for durability and effectiveness in preventing leaks. Therefore, specifying 26 gauge galvanized metal strikes an appropriate balance between strength, flexibility, and cost for typical roofing installations.