Here s a cleaning guide from a manufacturer of standing seam roof products just as a sample but really you need to find out exactly what s on your house.
How to clean a standing seam metal roof.
Once each panel is clean rinse it immediately with clean water to prevent streaks and film.
To remove severe rust stains.
If water alone isn t enough to remove common dirt and debris mix 1 4 cup detergent including mild laundry detergents car washing soap mild dish soap per gallon of water.
Working on any roof is dangerous and slick metal roofs with a steep pitch are particularly perilous.
Then wipe the panel again with a cloth or sponge soaked in plain water.
Soak your cloth or sponge in the water detergent mixture.
Scrub from the bottom of the panel upward in a left to right back and forth fashion.
Spray the roof with the diluted substance and let it sit for about an hour.
To remove algae and moss growth from the roof dissolve one cup of ammonia for every 5 gallons of water used and work from the top to the bottom.
Vinegar bleach ammonia and salt will all effectively change the ph level of your roof allowing you to clean it.
5 parts water 1 part diluted hydrochloric acid or citric acid or muriatic acid or oxalic acid or vinegar.
To remove difficult algae spots use only a wet cloth sponge or low pressure washer.
If heavy deposits of dirt or other contaminants begin to dull the finish then stronger methods may be needed.
Basically you put on various cleaning products via a garden hose sprayer scrub lightly with a soft brush presumably on a long pole if needed then rinse off with an excess of water.
Tips for working on steep metal roofs.
Remove the particles or pieces that are causing the rust stains.
Simple washing with plain water using hoses or pressure spray equipment is usually adequate.
Use a rag to apply to affected spots and use circular wiping motions.
Never mix chemicals together.
A variety of methods for removal of surface deposits are available.