Copper or Leaded Copper with FC siding
I’m doing a large Fiber Cement job (prepainted fiber cement clapboards)and the house has a few low slope porch roofs that the owner would like done in copper. The copper guy came around to look at the job and wants to use regular copper.
Where the copper will run up the side walls under the first clapboard, my feeling is I’ll have to isolate it from the FC due to corrosion/galvanic reaction between the copper and the cementitious board. Am I right? The copper guy says no need to.
I kind of like leaded copper better and if that’s used, maybe isolation wouldn’t be needed. Any thoughts?
Replies
I think that the galvanic problem is from wet cement reacting with copper. You have primed dry cement . That would give some isolation also.
I've not seen portland cement listed in a galvanic series chart, only metals.
We build cast-in-place concrete houses with copper skins on the exposed parts. There has been no corrosion problem.
PAHS Designer/Builder- Bury it!
I used plain copper flashing with Hardie siding on my house. I lived there for three years before I moved. It is only a short time, but there was no sign at all of any reaction. The copper was not even turning green yet.