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Pre-painted Galvalume® Sheet:
A Guide to Best Practices

A Guide to Best Practices

Steel Roofing With a little care and attention during service, prepainted GALVALUME sheet will provide an extended service life. While durable, factory-applied finishes for metal building panels will last many years longer than ordinary paints, they should be cleaned thoroughly on a routine basis whenever the finish is not washed by rain. Applications where the paint finish is automatically washed by rain, such as roofing, do not require this maintenance.

Cleaning restores the appearance of the building, making repainting unnecessary, and maintains a pleasing appearance, as well as removing the buildup of corrosive materials. Applications requiring maintenance cleaning include soffits, siding under eaves, garage doors and the undersides of eave gutters.


In many cases, washing the painted surface with clean water from a garden hose will remove most of the dirt and accumulated deposits. Ideally, washing should be done at least every six months and more frequently in coastal areas where marine salt spray is prevalent or where high levels of industrial fallout occur. In cases where spray washing is ineffective in cleaning stubborn dirt, mild detergents or household ammonia solutions can be used as described below. In all cases, test a small unobtrusive area for color-fastness before cleaning large areas.

  • Use one cup of Tide® (or other common detergent containing less than 0.5% phosphate) dissolved in five gallons of warm water. NOTE: Detergents containing greater than 0.5% phosphate are not recommended for use in general cleaning of building panels.
  • OR use one cup of household ammonia dissolved in five gallons of water at room temperature. Never mix ammonia with any kind of bleach.
  • Never blend cleaners and bleach yourself. If bleach and detergent are required, use detergents containing bleach.

Using either solution, work from the top to the bottom of panels with a well-soaked soft cloth, sponge, brush with very soft bristles, or low-pressure spray washer to clean the surface. Washing from the top down avoids streaking. Application should be gentle to prevent shiny spots. Scouring powders or industrial solvents are not recommended, since they may damage the paint film. Solvent-containing cleaners such as Fantastic® are very effective and can be used.

If mildew or other fungal growth is a problem and cannot be removed as described above, detergent containing bleach, such as Tide® with Bleach, is recommended. The surface should be thoroughly rinsed with water after cleaning to remove traces of detergent.

Touch-Up Paint

If scratches occur during handling and installation of painted roofing and siding, it may be desirable to use touch-up paint to repair the blemishes. Misuse or over-use can result in spoiling the overall appearance. Surface scratches which are not too obvious from a distance of six feet are generally best left untouched, since normal soiling and weathering will mask them.

Touch-up paint should be used sparingly and only to cover up those areas where paint has been removed. Areas to be touched-up should be wiped with mineral spirits to remove dirt, wax or other contaminants before colored touch-up is applied. Touch-up painting of large areas is not recommended, because these paints will not weather as well as factory-applied finishes. Contact the building panel manufacturer or original paint supplier for the appropriate touch-up system.

Aerosol or spray applications are not recommended for blemish or scratch repairs. The best tool for this type of repair is a good-quality ½ in. or smaller artist brush.

If cared for according to these instructions, prepainted GALVALUME sheet will maintain its original appearance longer.