Calcium Chloride Vs. Potassium Chloride for Roofs

Roof Snow/Ice Dams Issues and Dangers

• Snow and ice left on rooftops during winter pose many potential problems. Roofs, particularly older roofs, may collapse from heavy snow, as well as roof leaks and water damage. Ice dams are another potential threat. Ice dams occur when a ridge of ice forms at roof edges. They prevent snow from draining off the roof and can result in leaks in walls and ceilings as well as damaging insulation. Ice dams can slide off roofs, injuring passersby.

Potassium Chloride

• Potassium chloride comes in irregularly shaped white or off-white crystals. It is frequently used as a deicer because it does not damage vegetation. Its lowest melting temperature is 12 degrees Fahrenheit. It is a favorite deicer of airports, as it does not chemically bind to concrete or steel roofs. Considered an environmentally safe deicer, potassium chloride increases the number of freeze-thaw cycles, which can damage concrete due to freeze-related expansion. Potassium chloride leaves a white residue and is one of the slower deicing products.

Calcium Chloride

• Chloride, calcium chloride comes in irregularly shaped white crystals and cause little harm to vegetation. It does not chemically bind to concrete. While used as a calcium source for certain vegetables and fruits, calcium chloride may burn plants if applied in heavy doses. One of the faster deicing products at any temperature, calcium chloride expels heat as it dissolves and melts ice very quickly at temperatures down to minus 20 F. It can take moisture from the air even after ice has melted, causing surfaces to remain damp. It leaves no residue post-application and is considered an environmentally friendly deicer.

Choosing

• Both potassium chloride and calcium chloride are effective, environmentally friendly deicers. Neither attaches to concrete, which is helpful in terms of melting ice and snow off commercial buildings, although potassium chloride does run the risk of freeze-thaw expansion issues. Using either is a safe alternative to sodium chloride in terms of runoff and potential vegetation damage, although potassium chloride requires more cleanup because it leaves behind a white residue. Roofs with little snow and ice can benefit from an application of either product, although heavy snow and ice accumulation does better with calcium chloride, which is the faster acting of the two.