Anyone that has pre-painted metal roofing or siding will eventually need to clean it. It is recommended that cleaning either of these be accomplished with a mild solution of detergent.

This detergent solution should be made from a tri-sodium phosphate, for example, the laundry detergent name brand Spic-N-Span. In addition, many liquid dishwashing soaps would work for minor cleaning of pre-painted roofing or siding.

A stronger solution may be needed for more dirt build up on the panel surfaces. Panels may streak while cleaning. However this can be prevented by cleaning from the bottom of the panel and then rinsing the panels with clean water.

Pre-painted panels may develop more intense stains from mildew or dirt and mild detergents mentioned above may not completely clean them. In this case, a stronger cleaner is recommended to get the panels completely clean. Caution should be taken when using a stronger cleaner so there is no damage to the paint finish. A product such as Glass Wax, Window Wax. or something similar is readily available in most stores, and is suggested for the cleaning of heavy stains and dirt, while doing no harm to the pre-painted panel.

The following cleaning procedure is recommended (if not using Glass Wax, adjust instructions accordingly):

  1. Mix the “Glass Wax” product by shaking vigorously. (NOTE: If the “GlassWax” product is not mixed completely it may lose some cleaning efficiency.)
  2. Soak a heavy cloth, or sponge, with “GlassWax”. Beginning at the bottom portion of a panel section, wipe in a left-to-right motion until clean.
  3. If a panel becomes difficult to clean, continue rubbing longer, but do not increase pressure.
  4. When a panel section is clean, rinse the washed panels with fresh water.
  5. As each section of roof or panel siding washed, that area should be wiped again with a clean, wet cloth to be sure no cleaner remains on the panel surface. Be sure the final wiping is done with a cloth or sponge that is continually rinsed with clean water.
  6. In case the cleaner is not rinsed off completely, it will leave a light film on the panel surface. To remove this film, rub the area with a soft, dry cloth.

It is possible that the area to be cleaned has been exposed to heavy fungal growth or intense mildew. If the above procedure does not get the panels appropriately clean, the following mixture should do the job:

Supplies needed:

  • one gallon bleach
  • five gallons water
  • one cup mild soap (such as Ivory Liquid)

Mix the ingredients together and wipe the panels, still in a back-and-forth, left-to-right motion. This cleaning solution should not be allowed to dry on the panels as they are being cleaned, but instead should be rinsed along the way. All panels should then be rinsed one final time with fresh water when cleaning is finished.