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TOPIC: Galvalume

metal filings left on galvalum standing seam

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I have a standing seam galvalume roof on my new home under construction now. I live in a coastal area and my house fronts a brackish bay. Metal filings were not cleaned off of the roof properly and have rusted. The damage is scattered over the entire roof surface. The contractor has been unable to remove the all of filings although he tried to remove with soft scrub cleanser. The remaining filings are rusting again, of course. Will the filings and rust or use of an abrasive cleanser have a detrimental affect on the longevity of my new roof? I am also seeing rust on the cut edges of the panels, is this normal and could this continue and damage the panel?
Guest User

12/27/2003
In virtually all cases, manufacturer instructions for steel roofing require that the product be cut with a shearing action and now cut with a typical sawblade or abrasive disc. It sounds like your roofing panels were cut with an abrasive disc or sawblade. You need to contact the roofing manufacturer and see how this affects the warranty on the roofing panels. Also, depending upon the type of coating on the metal, permanent damage could have occurred to the finish. Todd Miller
Todd Miller
Isaiah Industries, Inc.

12/28/2003
Is it possible that that you're not seeing filings but pit corrosion? A site that discusses your hot-dipped roofing says it is "Not recommended in the pressence of animals, lime dust or cement dust or other agricultural applications." http://www.sealslumber.com/steelroofing.htm I have a similar problem and it is due to concrete dust getting on the galvinized coating. Sounds like more than cleaning might be required.
Guest User

12/29/2003
Thanks for the help Todd. I am making arrangements for the manufacutrer of the panel material (Drexel) to make a site visit. The roofing contractor is telling me that there is nothing to worry about but I am very uncomfortable with this rust problem on a brand new roof. I think the roofing material has been mishandled--at least. Do you think the rust on the edge will continue to deteriorate the panel?
Guest User

12/30/2003
Thanks for the help. Is there some way I can differentiate the source of the rust spots? There is a small raised "bump" on the panel surface at the rust spots. Do you think this rust will effect the longevity of the roofing material? Will it progress? What do you make of the rust on the cut edge of the panel? Todd thinks it was cut with a saw or something similar.
Guest User

12/30/2003
I am glad that the metal supplier is going to take a look at this. Drexel is primarily a metal coil supplier to folks who then have their own forming machines. However, they have also recently started to handle a line of metal roofing which is produced for them on a private label basis. The folks at Drexel are good people. Rust will continue to creep from edges over time. The speed with which this happens depends a lot on your climate. Wetter and salt environments are the harshest of course. The metal probably has a Kynar/Hylar coating. These finishes are top of the line but, chemically, they are "thermosetting" meaning that with heat (such as that from a red-hot metal shard), they will soften a bit, allowing the shard to sort of meld with the paint. This causes the shards to be firmly embedded.
Guest User

12/30/2003