Does Salt Damage Asphalt Ceiling Shingles?

The Facts

• Although asphalt shingles are not structurally harmed by the use of rock salt, their appearance is often harmed by reactions among the salt, the melting ice and the shingles. Many asphalt ceiling shingle manufacturers warn against the use of salt in the instructions provided with their products because of the discoloration that may occur.

Staining

• Salt leaves a residue on the surface of the shingles when used, and can also cause or speed up corrosion in the gutters along the roof line. In addition to the residue left on the shingles, the use of salt to de-ice a roof will lead to staining of the surface of the shingles.

Other fixtures

• Metal gutters, the downspout and the flashing on the roof are also adversely affected by the use of salt to de-ice the roof. The residue that builds up on the shingles can also build up on the metal, causing rust or other corrosion and thus damaging the structure of the fixtures.

Consideration

• Alternative de-icing materials should be considered if the structure of the fixtures and the color of the shingles is important. However, any de-icer that contains chloride, such as potassium chloride fertilizer or magnesium chloride, have the same, or similar, corrosive properties to rock salt, which is composed of sodium chloride. It is therefore important to consider the ingredients of any alternative de-icer before use.