The turret was the only standing seam area I saw. And it wasn’t a true standing seam either. The roof is a joke. The house has 5v barn metal. Good for a few years until the leaks become terrible. Step flashing on top of the panels??? I have made detailed reports many a time and the roofer??? loses.
The cap? When using ‘standing seam’, you use a 8" cleat that’s attached to the deck and reappears from the finished seam, folded over the finished seam and pop=riveted in place.
Here’s a standing seam roof I did last month.
http://www.albertsroofing.com/Tin%20Roofing%20photo_gallery.htm
I have many detailed pics. You would have to e-mail for specific ones I might have.
Frank at albertsroofing dot com