DIYs & How-To's

How to Properly Clean a Painted Metal Roof

roof cleaning in bryan roofing

Keeping your Bryan roof clean is a part of normal roofing maintenance.  Over the course of time painted metal roofs will appear discolored in areas where dirt and grime accumulate.  Long term exposure to the sun also creates a “chalking effect” where the metal appears lightened in color when compared to other areas of the roof.

Simple forms of roof cleaning like a light washing with a water hose will prevent algae and other agents from forming on the roof.   However, many metal roof owners want to retain or restore the luster that their metal roof provided when it was brand new.  In order to restore the original appearance of the only a light annual washing with ammonia and detergent is necessary.  Homeowners should always test a small section of the roof before proceeding to the entire roof.

Washing a roof is actually a fairly simple process.  Homeowners need only a water hose with enough pressure to reach all areas of the roof properly and a method of dispersing detergent and soap to the roof, usually by attaching a soap receptacle on the water hose line.

Polyester Coatings Care

To remove primarily dirt, use one cup of detergent like “ALL”.  The detergent you use should contain less than .5% phosphate.  Higher concentrations are not recommended for general cleaning.  Never mix dangerous chemicals, especially with compounds that contain bleach and ammonia.

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.  To remove difficult algae spots, use only a wet cloth, sponge, or low pressure washer.  Using any stronger scouring materials will result in damage to the protective film, leaving additional areas for dirt accumulation.

Feel free to use solvents that contain cleaners like Formula 409 without concern as they come with the proper mixture ratios for algae and mildew removal.  If all else fails, homeowners can use common bleach mixed at a ratio of 1:5 and 1 cup of mild soap, to wash away mold and other fungal pests.

Once the roof has been washed completely, a full rinse should be done.  The rinse should be done with soap and ammonia free (only water), and should remove all of the cleaning compounds and associated residue.  If residue is left on the roof for an extended period of time, it will erode the outer protective film later.

Annual roof cleanings are part of the normal roof maintenance process and should be done at least once a year for optimal performance and shine.  Additionally, routine washes also help identify any trouble spots with your roof.  If homeowners are unable to perform their own roof washing, then they should look for a Bryan roofing contractor that will include normal roof washing as part of a routine maintenance program.  To learn more about proper roof maintenance and care that will make you roof last longer than its warranty terms, contact Schulte Roofing.

Reference: 1997. Technical Bulletin 1050. Metal Roof Coating Maintenance. 7/97.