This is TCS II; it has a core of stainless steel with a zinc/tin overlay. Look at a dime; copper in the middle and shiny nickel/chromium on the outside; TCSII is bonded and laminated in very much the same way.
Why laminate the stainless you ask? Well, stainless steel stays bright and shiny forever, thats not the look most architects are looking for. The zinc overlay on the stainless core starts out shiny and then develops a patina; a light gray color. By marrying these two metals together you get the best of both worlds; you get the longevity of stainless steel and the beauty of zinc.
TCSII is one of the most durable metal roofing products available in the world, during corrosion tests it has surpassed all other metal roofs; even copper.
Because it lasts virtually forever, TCSII demands precision, all the flashings and transitions must be mechanically sealed; that means that all overlapping pieces of metal are folded over twice to make a waterproof joint. Caulk and sealant will only last a few years, so any detail that relies on it will fail long before the roof is ready to give up.
There isn’t one drop of caulk on this entire roof.
The shingles you see on the other areas are GAF Timberline Weathered Wood; great shingles.
The zinc coating over the stainless will form a patina in about a year; the final patina will be an even cloudy gray. The panels are shipped with a light protective varnish; the blotches you see are places where my knees and tools have worn the varnish off’; these spots will disappear in a month or so.
If you would like to learn more give me a call or you can visit https://www.follansbeeroofing.com/products/TCSII.aspx