Underbody Coating

Undercoating is the sprayed application of a wax or rubber-based composite onto the entire underside of the vehicle. It’s designed to create a rust-proof layer between the underside of the vehicle and the water, ice, and salt of the road.

Here in Canada, the roads we drive on can be tough on the underside of our vehicles. The spreading of de-icing salt every winter means that this section of the vehicle is often in direct contact with a corrosive agent. The fact that the underside of a vehicle isn’t easily visible, and can’t be easily washed, ensures any patches of rust can easily worsen over time without being detected.

Applying an undercoat to a vehicle usually only takes a single day, so long as sufficient time is given for the applied coating to fully dry and adhere to the vehicle. Over time, this layer will be worn down, meaning that a vehicle operating in a climate with substantial amounts of rain, slush, and salt hitting the underside of the vehicle should be undercoated at least once every few years to ensure full protection.

Types

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.

Function

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.

Benefits

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

Considerations

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.