What Is Undercoating for Cars?

Undercoating is a rust mitigation strategy for your vehicle. Although newer cars are built to resist rust more effectively than older models, rust is still a concern. Taking preventive measures early can extend your vehicle’s lifespan and minimize the need to address problems later. This article explores the dangers of rust, prevention strategies, and the different types of undercoating.

Why Prevent Rust?

Neglected rust can escalate from a minor cosmetic issue into a significant safety and repair concern. Spreading rust compromises the fuel tank housing, chassis, transmission, drivetrain, suspension, wheel wells, and other components. It can also weaken the vehicle’s structural integrity, diminishing its ability to protect occupants in a collision. 

Rustproofing vs. Undercoating

Rust prevention is essential, as rust removal is both tedious and labor-intensive. Two common mitigation measures are rustproofing and undercoating. Rustproofing involves a professional applying protective wax to the vehicle surfaces that are most susceptible to rust.

Undercoating entails spraying the entire undercarriage of the vehicle with rubber, polyurethane, wax, oil, or asphalt-based coating. This application is designed to form a protective barrier between the undercarriage and moisture from the road.

What Are the Different Types of Undercoating?

There are five primary types of undercoating. 

1. Rubberized: A rubberized undercoating is applied to the quarter panels and wheel wells, as well as to the undercarriage. This coating not only protects against road contaminants but also provides sound insulation. Once dry, it becomes rubbery and can be painted over or removed with a special spray. While rubberized coating is the most popular option and tends to last longer, it works best on newer surfaces. Its application is more complicated than other options, so it is advisable to have a professional apply the coating.
2. Polyurethane: Requires more preparation, including sanding and applying an etching primer. A polyurethane sealant is generally quicker to apply. This sealant enters hard-to-reach areas to protect unoxidized metal, and like a rubberized coating, it can be painted over. 
3. Wax or paraffin-based: Wax coatings do not completely harden or dry. While they are the most affordable and quickest undercoating to apply, this type of coating requires annual reapplication, if not more frequently, and must be stripped before each reapplication.
4. Oil: An oil-based undercoating should be applied annually and can be a do-it-yourself project. Providing extensive protection, the oil coating can be applied to rusted surfaces and can also penetrate the inner crevices of the vehicle to safeguard against rust. 
5. Asphalt-based undercoating: Typically reserved for heavy trucks, asphalt undercoating enhances resilience to rocks and other road substances. This type of coating necessitates professional application, has a longer drying time, and cannot be painted over. 

Many undercoating options are available based on your needs, budget, and comfort level with self-application. Dealerships may charge over $800 for undercoating, while garages might charge a few hundred dollars. However, some individuals can complete the process themselves for about $100. For those choosing a DIY approach, 16-ounce rubberized undercoating spray cans can be found in the $24 to $54 range. 

Summary

Undercoating is an effective method to prevent rust from forming on your vehicle. It’s an important consideration for those in colder or more humid environments, especially if your vehicle is an older model that lacks the same level of corrosion protection as newer vehicles. 

Matt Yantakosol is a lifelong automotive enthusiast and former consultant focused on the consumer aspect of the industry. He has traveled to New York, Detroit, Chicago, L.A., Paris, Geneva, Frankfurt, and Tokyo Auto Shows to track and observe the newest industry innovations. In addition to JDPower.com, Matt's writing has appeared on Pcarmarket.com.

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