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Cleaning Metal Roof: No Pressure Cleaning

Cleaning a metal roof is a good way to enhance the appearance of your home or commercial building. However, the task of cleaning metal roofs can be more difficult than it appears. But it doesn’t have to be. 

Metal roofs can be difficult to clean. They get very slippery, metal roofing can bend and dent easily, they are very sharp and if the cleaning is done incorrectly they can be permanently damaged. A lot can go wrong when trying to clean a metal roof. One of the most common things we have seen when cleaning metal roofs are footprints left from the previous company. Oftentimes metal roofs, especially darker colored material, oxidize from the natural elements. When oxidized metal roofing material is walked on or treated incorrectly with chemicals the results can be irreversible. 

Until recently, the two common roof cleaning methods have been Pressure Cleaning and Soft Washing. While these cleaning methods can be effective they are not a permanent cleaning solution.

Pressure washing a metal roof is a lengthy process that can cause damage to the roof as well as the gutters. The high pressure applied to the roof surface can loosen fasteners, damage the surface as well as potentially cause leaks in the roof. Not to mention pressure cleaning requires constant walking on the roofs during the cleaning. As roof cleaning processes evolve, Pressure cleaning roofs is slowly becoming an obsolete practice. Simply due to the potential damaging effects, rising insurance premiums, safety concerns and local regulations.

What about soft washing? A soft wash is very common in roof cleaning practice and often takes the place of pressure cleaning in several applications. A soft wash is a mix of chemicals and water that is applied to the surface with low pressure pumps. Below are the most common chemicals used during a soft wash treatment.

Bleach and Chlorine Based Products:

  • Does not penetrate root structure
  • Can leach into the soil
  • Can ruin gutters/ break down silicone joints
  • Masks problem – removes color/pigment but not all microscopic spores
  • Temporary solution – Only kills 65% of spores
  • Corrosive, toxic, strong odor
  • Can damage people, vehicles, landscaping, structures.
  • Dries out shingles; causes nails to rust.
  • Bleaches tile color

Sodium Hydroxide Based Cleaners:

  • Highly caustic, corrosive & toxic (Lye based)
  • (Example. Oven Cleaner)
  • Masks problem – removes color/pigment but not all microscopic spores
  • Very hard to rinse
  • Can discolor paint
  • Temporary solution
  • Can damage vehicles, people, landscaping, structures. Can stain roofs!

If the top two options don’t appeal to you, then we recommend simply applying Citra-Shield to your metal roof and let mother nature gently clean the roof over time. When done correctly Citra-Shield will not only remove the algae that is causing black/green/purple stains on your metal roof, it will also prevent these stains from reoccurring in the future. Citra-Shield is a permanent solution to keeping you roof free and clean of mold, mildew, algae and fungus. The only dis-advantage of Citra-Shield is that you will have to be patience and let the product do its work. Every roof we have ever treated becomes clean and stays clean long after application.

We always recommend hiring a professional Citra-Shield Applicator when applying our products to a roof. However if you prefer to do it yourself, always follow the manufacturer instructions. If you must get on a metal roof wear the recommended OSAH safety harness and fall protection.