The Skinny on Waterproof Car Covers

Covercraft has the 1972 MG covered

Everyone agrees that a car cover should protect a vehicle from rain or snow.  This is why many car covers advertise the fact that they stop water completely, going so far as to use plastic barriers that keep moisture “out.” However, a good car cover isn’t supposed to be impervious to water – it’s merely supposed to protect from external water. What any car cover purchaser should want is a cover that acts as a one-way barrier: water shouldn’t be able to drip through, but it should be able to get out.

Beware Car Covers That Are 100% Waterproof

Are you looking at a car cover that’s described as “100% waterproof?” Keep looking. A car cover that blocks all rain and water from passing through the fabric seems like a good idea, in theory, but it’s a bad idea in reality. Waterproof car covers are typically made of all plastic, or plastic topped, materials. These covers have no ability to breathe, and that lack of airflow creates condensation build up, often between the bottom layer of the cover and your vehicle’s paint.

If you place a waterproof layer of plastic over your car, your vehicle will soon be surrounded by moisture (which condenses from ambient air), and that moisture will have no way to escape. This creates the perfect breeding ground for mold, mildew, and rust — exactly the sort of damage car covers are supposed to prevent.

Car covers need to breathe, meaning that they need to allow air and moisture to flow through the cover. Impermeable barriers like simple plastic might seem like a good idea, but even one rainy day will prove that moisture is easily trapped under a cheap car cover.

Car Covers Do More Than Prevent Moisture

Covercraft Weather Shield

Many people assume that a 100% waterproof car cover is necessary because they believe water is the most serious threat to the car they’re trying to protect.

While it’s true that rain and snow can contain contaminants that can damage paint, they’re not the only threats to a covered car. Dust can sometimes contain chemicals that can etch paint. Wind can cause pitting on an uncovered car, and can cause scratches and scuffs if a car cover fits poorly. UV rays can cause paint fade and damage interiors. Finally, covered cars can be bumped into by people, pets, etc.

Thus, the “ultimate” car cover has a soft underside that prevents scratches when bumped, is custom fit so it doesn’t shift or buffet in the wind, keeps water out while allowing airflow, and stops dust.

Choosing The Best Car Cover

Covercraft Block-It

First, if you store your car in a rain-free environment (shed, garage, storage facility, etc.), water resistance isn’t even necessary. You’ll want to look for a high quality indoor car cover instead. If you do leave your car outside, you’ll want to shop for a car cover that offers protection against the elements posing the biggest threat.

Most car covers protect against one or many of these elements:

  • Dust
  • Dirt
  • UV rays
  • Acid rain
  • Bird droppings
  • …and more

The fabric and construction typically determines the level of protection against each element.

Bottom line: A waterproof cover isn’t necessarily a good car cover. While outdoor car covers should stop rain and snow, they should also allow airflow that keeps moisture from building up.


A self-described “car nerd,” Jason is a automotive columnist who has written for the eBay Motors blog, Motor Car Digest, as well as his own sites TundraHeadquarters.com and AccurateAutoAdvice. With an engineering degree, a full-time job in the automotive parts industry, and a decade of experience working in auto dealerships, Jason brings an interesting perspective on all things automotive.

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