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INTRODUCTIONPrefinished sheet steel building products, such as wall androof cladding, liner sheet, flashing, and associated items, haveexperienced an enviable growth record over the past twenty years.Coil coated prefinished sheet steel in a variety of colors and paintsystems has greatly enhanced the appearance of thousands ofindustrial, commercial, institutional, recreational, residential, andfarm buildings; providing an economical, durable and attractivealternative to traditional materials. As with all materials, a little care and maintenance pays off handsomely in terms of longevityand repair costs. The recommendations which follow have been learned first hand and represent the collective industry experiencewith thin-film paint systems applied to metallic coated sheetsteel by the coil coating process. In this publication the term%u201cthin-film paint system%u201d refers to a modified silicone polyester or a fluorocarbon type having a coating thickness about 25um.When the guidelines listed below have been observed, thinfilm paint systems have been used successfully for all types ofenvironments other than severe industrial atmospheres whichrequire special consideration. The guidelines are not intendedfor barrier coatings, laminates, and new formulations whichhave different characteristics than the thin-film paint systems onwhich these guidelines are predicated.DESIGN, DETAIL & COLOR CONSIDERATIONS%u2022 Architectural details should permit natural rain-flow cleaning of the cladding.%u2022 On roofs or other horizontal surfaces, standing water can contribute to the premature failure of the paint system and substrate. Detailing should preclude damming or ponding of rain-flow at stacks, ventilators, air control equipment and other objects.%u2022 Due to color tolerances, there may be differences in color shade between production runs. Where possible, ensure that each building elevation is clad with material from the same production lot. If different production lots must be used on one elevation, as may occur when making an addition to an existing building, try to begin the cladding on an elevation change or break in the building to minimize the effect of possible color variations.%u2022 A sufficient roof slope to permit drainage is recommended (e.g. 1 in 48 minimum, and greater where rainfall is heavy, drainage is restricted, etc.).%u2022 Roof surfaces, defined as those up to 60 degrees from the horizontal, are subject to more severe exposure conditions than vertical surfaces. Conditions such as extended exposure to ultraviolet light may be resisted by using a light color for the roof. Acid precipitation and drip edge puddling are other conditions that could affect the appearances and durability of the paint finish. Drip edge puddling may be minimized with a steeper roof slope or by modifying the edge details. If severe acid precipitation is experienced, a more resistant prefinished system may be required.%u2022 The building design should seek to minimize the installation of mechanical equipment on a prefinished roof. Walkways should be provided where regular traffic is necessary for maintenance. In wall applications, horizontal portions of the cladding and base flashing should be sloped to prevent moisture from puddling.%u2022 Walls shadowed by overhangs and all soffit areas have an increased time of wetness relative to other areas. The increased time of wetness creates a more aggressive environment for the cladding affected so; therefore, architectural details should try to minimize these areas.%u2022 To decrease the visibility of %u201coil canning%u201d, select an adequate material thickness, a narrower flute and a lighter color.%u2022 To prevent unwanted galvanic corrosion, the architectural details should not allow the contact of dissimilar metals (e.g. steel and aluminum or copper) or should provide an adequate means of separation. The path of rainfall runoff should also be directed to prevent water runoff across one type of material to another which can also cause galvanic corrosion.SITE STORAGE%u2022 Storage time should be minimized by installing the cladding panels as soon as possible after delivery. Good planning will ensure that panels are used on a first-in first-out basis.%u2022 If cladding must be stored for an extended period, the most desirable storage place is under-roof in a cool, dry, well ventilated area.CARE AND MAINTENANCEOF PREFINISHED SHEET STEEL PRODUCTSJULY, 2025