Copper nails and cedar

project development & documentation
1

I’ve seen several practice questions which have all mostly agreed that copper nails should not be used with red cedar or redwood. However, looking at page 233 of Architectural Graphic Standards (student version. for any other version, I’m on the page called Flashing: An introduction, in the thermal and moisture protection chapter) I’m looking at the galvanic chart on that page and it says that with red cedar and copper have no galvanic action?

So can you use copper with red cedar “under normal conditions”? Additionally, when is it appropriate to use copper fasteners and flashing. Per the chart I mentioned above, copper is getting a lot of attention on practice questions for something that can’t really be used with anything ha!

2

Hey, @coachdarionziegler or @coachchrishopstock could you please take a look at this question?

Thanks,
Piper

3

Hi @Shikha thanks for the question!
For everyone’s reference, the chart that we’re discussing is on page 197 of AGS, 12th edition.
I agree that the chart says that copper can be used with redwoods and cedar, and I agree that in general they can be used together. The copper is likely to develop streaking from the tannins in these woods, but it’s not going to degrade the flashing to the point to failure. It’s an aesthetic issue.
Copper flashings can be used with other materials such as slate and asphalt roofs, or with other types of wood siding, and with man-made (PVC) siding materials.