Which two metals are recognized as solderable according to the NRCA?

The correct choice identifies galvanized steel and stainless steel as metals recognized as solderable according to the National Roofing Contractors Association (NRCA). Soldering is a process used in roofing to join metals together, and the ability to solder depends on the compatibility of the metal surfaces with solder materials.

Galvanized steel is coated with a layer of zinc, which can be soldered effectively because solder can bond well to the zinc surface when properly processed. Stainless steel, while typically more challenging to solder due to its passivation layer, can still be soldered using specific techniques and fluxes that enhance adhesion.

In contrast, the other options involve metals that either cannot be soldered effectively or require specialized techniques that are not usually part of standard roofing practices. For example, aluminum and copper, while they can be joined using other methods like welding or brazing, are not typically soldered in roofing applications. Similarly, brass and bronze may not align with conventional soldering due to their alloy compositions, which can lead to unsatisfactory soldering results. Lastly, steel and iron may not be specifically recognized as solderable in the context of roofing due to potential issues with corrosion and the suitability of solder for bonding these materials effectively. Therefore, galvanized steel and stainless steel are the