Waterproof vs Breathable Vehicle Covers
'Waterproof' Vehicle Covers
To be considered 100% waterproof, a waterproof car cover fabric must block moisture of any kind from passing through the material, seams, hem, vents, pockets, and any other part of the cover.
In other words, a ‘waterproof’ car cover should act as an impenetrable barrier between external moisture and your vehicle, and that at no time during a 100°F summer day or after a hard spring rain storm, should you be able to remove the cover and find evidence of wetness or moisture.
Typically, these types of inexpensive protective covers are made from vinyl (PVC), Nylon, or polyethylene (PE), and are prevalent in low end covers as well as tarpaulins.
'Breathable' Vehicle Covers
Under humid conditions, water droplets form (like dew) underneath the cover itself. When trapped for an extended period of time, those water droplets will not only cause mold and mildew to form, but will also erode exposed surfaces, such as your vehicle's paint job.
Breathable car covers allow trapped moisture and condensation to evaporate quickly through the cover itself, thus shortening the amount of time your vehicle is exposed to wet, humid conditions. If water gets through or forms due to condensation, you have nothing to worry about as the water will evaporate before any corrosion can begin.
Your Best Option
Simply put, no fabric or ‘special top-coating’ is everlasting and will eventually allow moisture to pass through it. Water alone won’t negatively affect your vehicle’s surface. However, when moisture is trapped under the cover due to ‘100% waterproof’ covers, harmful agents can develop due to the material type and corrosion is inevitable. We recommend choosing a ‘water-resistant’ vehicle cover that will block moisture while still allowing breathability over time.
For more information on breathable and water-resistant covers, read our post on The Cover Blog about Dispelling the Myth of Waterproof Covers.