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Galvalum roofing corrosion

I just had a galvalum roof of 29 gauge placed on the roof of my historical property in Deland, Florida. In this region of Florida near the ocean and St. Johns River the high salt air warrants anti-corrosive metal for architectural work. However, I was warned not to place a finial made of copper on the roof copula or the copper would cause rust to set in from the water run-off. Hmmm? I thought galvalum was non-corrosive and being that it is produced in Singapore, I am exhausted in finding out whether or not this is true. If it is, I do not mind resurfacing the finial, but what would be compatible with galvalum? Anyone have suggestions?

Patricia Moon
- Orlando, Florida
2005

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If you bond different metals together you can get a galvanic reaction. It isn't that either is corrosive but rather that they aren't compatible under the weather conditions you speak of. It is a simple chemical reaction and if you were warned not to use the two together then they must have a history of galvanic reaction.
Hope this helps.

Suzanne Osborne
- North Myrtle Beach, South Carolina
2005

My experience with Galvalum is that it is typically very thin, and non-corrosive is only for surfaces that are not marred. In practice, any fastener may present a problem as will the penetration and/or fasteners used to attach the finial. (the use of rubber washers with the fasteners can help). Also, there will be a green patina that will leech from the finial. Since this cannot be closely inspected, alternatives include something that looks like copper but isn't, or copper that is heavily lacquered. (BTW, we worked on your courthouse... nice building.)

Thomas M. Matthews
contractor - Lexington, Kentucky
2005

I recently, two months ago, had a Galvalume Roof installed on our home. It is in the bright silver finish. We have a problem with red chalk stains remaining on the finish. I've tried to pressure wash it off with a 2400psi washer, a mild car wash and even scrub brushing it off. Nothing seems to even come close to cleaning it off. Does any one have any solutions or the same problem? It looks terrible!

Wyatt A. Lewis
N/A - Umatilla, Florida
2007

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Time will likely fade or wear off the chalk. I had this issue also and after 1 year it seems to have disappeared.

I have a question about corrosion using Galvalum roofing - will using bleach or trisodium phosphate ⇦this on eBay or Amazon [affil links] to clean the siding cause corrosion of the roofing? It is extremely thin and anything that takes the protective surface off could cause rapid corrosion?

Mark Claussen
- Sugar Land, Texas
2007