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Repainting 25yr old metal roof

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Guest User
6/27/2002
I am being directed by an architect to "powerwash w/sand injected water jetblast @ 45,000psi" as the surface prep for the repainting of a 25yr old metal roof. I have expressed my concern that the use of ultra-high pressue washing will distort & pit the metal roofing to the point that replacement may be required, at the contractor's expense of course. Additionally, the Architect has specified a urethane primer with two coats of epoxy topped with an acrylic polyurethane clear coat. My concern here is the elasticity of the finish product. The color of the roof is dark brown, 12:12 Pitch, with southern exposure. We are located in New Hampshire. Any standards for repainting or prep work that I can refer to?
Guest User
6/27/2002
I am being directed by an architect to "powerwash w/sand injected water jetblast @ 45,000psi" as the surface prep for the repainting of a 25yr old metal roof. I have expressed my concern that the use of ultra-high pressue washing will distort & pit the metal roofing to the point that replacement may be required, at the contractor's expense of course. Additionally, the Architect has specified a urethane primer with two coats of epoxy topped with an acrylic polyurethane clear coat. My concern here is the elasticity of the finish product. The color of the roof is dark brown, 12:12 Pitch, with southern exposure. We are located in New Hampshire. Any standards for repainting or prep work that I can refer to?
Todd Miller
Isaiah Industries, Inc.
6/28/2002
Power washing the roof to clean it thoroughly and, as best as possible, remove any old paint, is a good idea. I don't know about the sand injection though. I guess you could experiement and see if it hurts the metal. Apparently, for some reason, this architect really wants the old paint off of there. However, if there is not presently an obvious adhesion problem with the old paint, I wouldn't be overly concerned if it stays in place. This architect is also really suggesting a "top notch" procedure for the new coat. You have to weigh for yourself to what extent you want to go in terms of that. Actually, if you really want to do something good, I would put down a good primer (such as Sherwin Williams' Pro Cryl) and then apply a coating of an air-dry Kynar finish. Most of the metal roofing manufacturers on this website could help you come up with air-dry Kynar. It is costly but very durable and fade resistant. Good luck.
Guest User
8/16/2002
I'm curious. Since 50,000 psi water/abrasive streams are handy for cutting six foot thick concrete slabs I was wondering how much was left of the roof when you were done.
Guest User
9/5/2002
these guys learn out of a book with no hands on experience
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