"Old Tin" Metal Roofing

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Author Message Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 252 Registered: 10-2002 Posted on Tuesday, January 15, 2008 - 08:58 pm:    I have a project where the architect is asking for a galvanized corrugated steel sheet roof which is to be chemically treated to produce an "old tin" appearance. I am assuming that it is an acid which will remove some of the galvanizing to permit it to rust and, hopefully, achieve an aged appearance. Is anyone familiar with this process or a similar related process? Other questions include the suggested minimum gauge of the steel sheet, minimum galvanized coating, and any long term adverse effects from the treatment. The application is a sloped roof in a mountainous region (ie, high snow and wind loads) and will be used with adjacent [connected] cedar shake roof. Am I correct in assuming that there will be no chemical reaction between the cedar and the galvanizing. The intent is to include this same material as sheet flashings into stone walls. ....thanks PS: Do they still fabricate the original histiroric tin for roofing? Dave Metzger Senior Member Username: davemetzger Post Number: 242 Registered: 07-2001 Posted on Wednesday, January 16, 2008 - 07:58 am:    I had understood that what is referred to as "tin" roofs is actually terne, which historically has been steel coated with a lead-tin alloy but is now zinc-tin alloy coated. Why not just use that? Whether the metal is terne, or galvanized steel treated with a magic elixir, if left unpainted it will rust. And eventually pinhole and fail. Does the architect really want that? Cedar shingles can be fastened using galvanized nails, but they can leave black streaks on the wood. Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 253 Registered: 10-2002 Posted on Wednesday, January 16, 2008 - 10:28 am:    The original design intent was to use reclaimed old tin roofing that, for the most part, already had pinholes. The actual WP system was to be placed under the "old tin" roof in the form of a mod-bit system. I suggested either galvalum or terne metal systems which can at least be made watertight but the suggestion was rejected. The architect is now considering the treated corrugated galvanized steel which I feel uncomfortable with because of my concern for watertightness [ridge, hip, valleys, and other penetration flashings]. As a side note, I have field investigated many 200 year old DC rowhouses that had low-slope, flatseam tin roofs that were completely filled with pinholes [looked like looking through a screen from the underside] but THEY NEVER LEAKED. Never in my wildest imagination would I consider relying on that product in a new building, however. Lynn Javoroski CSI CCS LEED™ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 713 Registered: 07-2002 Posted on Wednesday, January 16, 2008 - 11:50 am:    http://us.rheinzink.de/ ? Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 254 Registered: 10-2002 Posted on Wednesday, January 16, 2008 - 12:08 pm:    Thanks, Lynn, but the design intent is to make it look like a 100 year old barn. Of course, old barns leak but that won't fly on this project. The major goal is to find out how to treat the various sheet metal options available. Anonymous   Posted on Wednesday, January 16, 2008 - 01:14 pm:    Ron, Did the client also ask for a cat? Christopher E. Grimm, CSI, CCS, LEED®-AP, MAI, RLA Senior Member Username: tsugaguy Post Number: 119 Registered: 06-2005 Posted on Wednesday, January 16, 2008 - 01:20 pm:    We recently spec'd Revere Copper Products "FreedomGray" for the tin look where curved dormers were used. http://www.reverecopper.com/freedom1.html has tin zinc alloy over copper, naturally weathers to tin appearance. You can find it in MASTERSPEC under sheet metal roofing section Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 697 Registered: 07-2002 Posted on Wednesday, January 16, 2008 - 01:32 pm:    I've used the Freedom Gray as well, and its a nice looking roof, but its not going to look 200 years old. there may be a problem with galvanized and cedar; the typical nailers and trim with cedar is copper because the oils in the cedar cause some corrosion with galvanized material. you might want to check your gutters, flashings and such to make sure the building doesn't age faster than your intention. Richard Howard, AIA CSI CCS LEED-AP Senior Member Username: rick_howard Post Number: 158 Registered: 07-2003 Posted on Wednesday, January 16, 2008 - 01:46 pm:    Try a little Hollywood magic. We recently used paint to simulate aging on metal roofs and other building elements for a theme park. We had photos of the look we wanted included with the construction documents and directed the painter to match it. He really got into the project and it turned out great; one of the few times I can recall where the workmanship exceeded expectations. Ron Beard CCS Senior Member Username: rm_beard_ccs Post Number: 255 Registered: 10-2002 Posted on Wednesday, January 16, 2008 - 06:34 pm:    Richard: Would you contact me at <beardccs@inbox.com>? Thanks Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 485 Registered: 05-2003 Posted on Wednesday, January 16, 2008 - 07:59 pm:    Richard, are you talking about paint products by Luminore www.luminore.com amazing stuff to simulate aged metal on almost any surface, one of our Florida Metal Fabricators turned us on to this product, it may be useful for what Ron is looking for.