CoatingsPro Magazine

NOV 2018

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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22 NOVEMBER 2018 COATINGSPROMAG.COM It is common to see some corrosion on older metal roofs, but when it is severe, you need to look more closely, particularly if the roof has been known to be leaking for an extended period of time. F rom time to time, roong contractors will encounter an existing metal roof rehab project only to be challenged as to whether the roof is suitable for a coating or not. Millions of square feet of existing metal roofs are coated each year, but before assuming all metal roofs are suitable for coating you should look a little deeper. Common Issues W hat is it about a metal roof that would make it unsuitable for coating? Metal roofs are unlike most other roong types. You need to be able to identify how to tell if a roof can't or shouldn't be coated before o•ering that as a solution to the facility owner. Here are some cases when an alternative solution may be the best choice: • Corrosion: Metal roofing is not a covering, it is a structural compo- nent of the building and its design. It is common to see some corrosion on older metal roofs, but when it is severe, you need to look more closely, particularly if the roof has been known to be leaking for an extended period of time. The panel end laps, curbs, equipment penetra- tions, ridge, and eave areas should be looked at carefully from inside the building as well as from outside on the roof. Long-term roof leaks can cause the structural purlins and/or eave struts to be reduced to something resembling Swiss cheese. If you see this, the building is structurally compromised, and a structural engineer with knowledge of metal roof/building systems needs to be involved. If the corrosion is severe and perforating of the roof panel itself is noticed, coating may also not be viable, as it can present a life safety walking hazard on the roof. • Fastener Problems: Leaky or badly corroded fasteners can also result in corroded weak areas in the roof panels immediately around the fasteners. The fasteners not only hold the roof down, but they trans- fer critical diaphragm strength to the entire structure. A fastener cap will cover a structural defect but not correct it. The cap will not keep the roof on the building in a storm or transfer diaphragm loads to the structure. Improperly coating a compromised building will likely hide the problems, but it may also put you in the liability chain should a structural failure occur. Legally, you are a roofing professional and should be able to recognize when you need to seek additional expert advice. Notes From the Field By Dale Nelson, President, Roof Hugger, LLC Retrot Systems Photo courtesy of Roof Hugger, LLC When Is Coating a Metal Roof Not the Best Choice?

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