steel pin nails into copper flashing
I’m shingling a dormer that has copper flashing around the bottom and side edges, and I freaked out when I saw that my helper had used the pin nailer and shot ordinary steel pin nails into the row of shingles underneath the four window sills across the front of the dormer. (everywhere else he used copper nails where the copper flashing would be penetrated). He used the pin nailer because the nail heads were so tiny they could be filled. But the reason I freaked out was because they penetrate the copper flashing. Now, two days later, I’ve read up on galvanic corrosion and I learned that the copper will stay intact but the pin nails will be sacrificed over time. Phew, I thought. I was afraid of some ugly staining of the copper that would drip down, but now I know that won’t happen. Before I did the research though, I thought I needed to remove those shingles so that the pin nails could be removed. I removed all the shingles and pin nails, and then proceeded to drive copper nails into each nail hole to close the holes in the copper flashing. Sealant wouldn’t have done the job because there was a layer of ice/water shield covering the copper and I just couldn’t be sure the sealer would work its way into the hole in the copper. That done, I’m cutting new shingles and am going to use the copper roofing nails and just paint over them.
Looking back, I’m thinking that what I did was a huge overreaction, and that I could have left the pin nails there, as long as I sealed over their little heads, followed by touch-up paint. Agree or disagree?
Replies
You did the right thing to remove the steel nails. Copper is a lifetime material, often lasting a century or more. The steel nails, no matter how you attempted to seal them, would have rusted away fairly quickly because the galvanic reaction is so strong. It doesn't take much moisture to facilitate it. Leaving the nails would have turned a century of service into only a few years.
Rather than 'paint over" the cu nails, use a tab about 3/4'' by 3'' under and fold it over the head of the nail after it is driven home.
Another option is Cu Poprivets..I do it every day.
Spheramid Enterprises Architectural Woodworks
There is no cure for stupid. R. White.
Sphere, I'm confused about the tab. You would make it out of a strip of copper? Then nail through it just below the fold-line? If I have that correct, wouldn't the folded-over tab of copper be too noticeable? I thought a copper roofing nail with a dab of paint would pretty much disappear into the face of the shingle, as viewed from the ground looking up to the second story dormer. As for pop-rivets, we used them to fabricate a sheetmetal duct, so I know how they work for that. You can actually use them to attach a shingle to a building? I'm trying to imagine that.
Yes. The tab is visable. But it looks better than painted head IMO.
Spheramid Enterprises Architectural Woodworks
There is no cure for stupid. R. White.
Galvanic corrosion varies immensely with location. I was using nylon T washers to isolate stainless screws from my copper sheathing. Ran out of T washers at the end and installed the last few without.
Almost a decade later, no corrosion showing. Not exactly arid here and these screws get wet every time it rains.
Which isn't an answer for you, just an observation.
PAHS Designer/Builder- Bury it!
I expect that was because there's not much of a battery effect between the copper and the stainless. I've often read that stainless steel screws are ok to use with copper.
By the way, when I read your screen name, VaTom, I couldn't help but notice it's just a split hair away in pronunciation from a French expression whose only difference is that it ends with an n sound instead of the m. It's "va t'en" and it means "get outa here!"
Lots of misinformation available. You might check a galvanic series list before assuming. Then combine that with area effect. Here's one:PAHS Designer/Builder- Bury it!
I've just recently started looking into using more copper. Thanks in a large part to Sphere's and seeyou's comments here. I recentlty ran across this link:
http://www.copper.org/innovations/homepage.html
One interesting point in that link is the relationship between nickle and copper. The main ingredient in stainless steel is nickle. Apparently copper gets along with nickle like a carpenter with a cold beer on a hot day. So stainless and copper should be the same.
Monel staples are part copper, part nickel. Said to be less likely to rust than stainless steel.
18/8 SS is 18% chromium, 8% nickle.
OTOH nickle is the biggest cost component in SS, about 60%.
I just realized that you're referring to sidewall shingles below the window sill, not the roof shingles. Sphere is referrring to a method to hold the copper apron in place when you can't nail it to the wall.
I'm guessing the shingles were so small you had to face nail them (only one course).
What you've ultimately done is fine, but you're right - it was an over reaction. What your helper did first was SOP.
Andrew Douglas: What have you been up to?
Jim White: Killin' time... It just won't die.
http://grantlogan.net/
Hey thanks. I can't figure out what SOP is, but I guess it's not so good.
SOP=standard operational procedure.
Andrew Douglas: What have you been up to? Jim White: Killin' time... It just won't die.
http://grantlogan.net/