Reroof stucco copper counterflashing over reused metal step flashing?

**We are almost finished with a reroof job with copper valleys. The roofer wants to reuse the old galvanized steel step flashing and apply copper counter flashing with a “nice caulk channel on top where we can seal it against the stucco to keep it from leaking.” **

** I said that I didn’t think you could use copper and other metals together and asked if this would cause corrosion? He said, “not really an issue when using copper.” Any advice? What is proper way to counter flash stucco? Is there actually a way to use copper step flashing in this situation? Thanks!**

How would you propose the roofer reflash stucco walls?

I would think it would be part of the bid, I.e., new copper or reuse the old. Aside from cost, copper is great, it lasts forever. In many cases, if done properly, it can be reused.

The step flashing is galvanized steel. I did not know you could put copper over galvanized steel.

I didn’t know it was galvanized steel either. My original question still exists. How to reflash the stucco walls without having to tear out stucco up the wall, install the flashing and then rebuild the stucco?

You are correct about the new copper causing corrosion on existing galvanized flashing. Best bet would be to go with his idea but use a heavy painted steel or stainless flashing. Copper is great but Only when all the flashings is copper.

https://www.grabberman.com/Media/TechnicalData/127.pdf Galvanic reaction chart…