What is Car Undercoating?

Undercoating provides an additional layer of protection and insulation to the undercarriage of a vehicle. Manufacturers may apply undercoating at the factory. It covers most of the car's underside, including floor boards, pans, gas tank, wheel wells, frame and suspension parts, mufflers and exhaust pipes. The effect can be likened to blackcoating a road or parking lot.

Undercoating materials adhere to metal, even if painted. Most come in pressurized cans for easy spray-on application, although an even spread may be tough to achieve without professional applicators. Ingredients used in manufacturing include fiberglass, rubber, ceramics, silicone and asphalt, or petroleum. Each has different properties in terms of heat retention and resistance, but all do offer protection against the elements and damage.

Undercoating protects the undercarriage, a car's most vulnerable area. Unlike visible portions of a vehicle, the undercarriage doesn't get washed regularly but does absorb most of the moisture, salt, grime and other substances you come in contact with as you drive.

In addition to protection from elemental damage, good undercoating can also reduce road and engine noise, leaving the passenger compartment quieter than before.

Even if you get a new car with undercoating from the dealer, keep in mind that undercoating wears off and ceases to be a benefit--typically within as little as 1 year. Worn, patchy undercoating can be a detriment as water and other elements then get trapped under the coat, further eroding metal.

Undercoating and rust proofing are not the same. Undercoating products don't cost as much as professional rust proofing, which treats metal with a thin clear coat, not the thick layers associated with undercoating.