In this expert article, we will focus on one of the most important aspects of every car cover — the material itself. There are many different materials available on the market today, but they vary significantly in their properties and overall performance. So how can you distinguish a high-quality material from a poor one? What should you pay attention to? Let’s take a closer look.
And straight to the point — the most important function of any car cover is the ability to allow water vapour to escape outward into the surrounding air, in other words, to “breathe”.
With indoor covers, we talk about breathability. Breathability describes the material’s resistance to the continuous evaporation of moisture while also determining how easily air can pass through the fabric from the outside environment toward the vehicle. Simply put, it reflects how easily the material can be ventilated. The lower the resistance, the better the material breathes. Breathability is usually achieved through the simple construction of a single-layer fabric commonly used for indoor covers. However, some products on the market trap moisture instead. How can you tell if a cover is breathable? Quite easily. Hold the material to your mouth and blow through it. If most of the air passes through, the cover offers very good breathability. If you do not have the opportunity to physically inspect the cover beforehand, look for this information in the product description. Manufacturers and retailers are usually proud to mention this important feature of an indoor car cover. If the information is missing entirely, it is probably not a coincidence.
With outdoor covers, the material’s ability to release water vapour is even more important. Here we refer to vapour permeability. Vapour permeability indicates how much moisture, measured in grams, can pass through one square metre of material over a 24-hour period. Unlike indoor covers, this property cannot be verified with a simple breathing test. The waterproof construction prevents direct airflow through the material and may therefore appear non-functional at first glance. In this case, you must rely on the technical specifications of the cover itself. Some outdoor covers available on the market are completely non-breathable. In such cases, ventilation openings may partially compensate for the lack of vapour permeability by allowing moisture to escape outward and away from the vehicle. These ventilation openings should be positioned at the highest points of the cover, where water vapour naturally rises. If an outdoor cover is neither vapour permeable nor equipped with ventilation openings, we would not recommend using it.
Not only vapour permeability, but also waterproofness is a key characteristic of every outdoor cover. Waterproofness refers to the material’s ability to withstand long-term water pressure. It is expressed as the height of the water column, measured in millimetres, that the fabric can resist before water begins to penetrate. The higher the water column rating, the greater the resistance to water penetration. Waterproofness is generally achieved in two ways — either through coatings or through water-repellent surface treatments. Coatings typically consist of polyurethane layers that effectively “seal the pores” of the material and reduce its ability to fully breathe. From the perspective of allowing water vapour to escape outward, water-repellent surface treatments are generally considered the preferable solution. There are many different types of treatments available, with the main difference being how long the cover remains water-resistant. No treatment lasts forever. Over time, effectiveness gradually decreases due to washing, use, and abrasion. To maintain proper performance, the treatment must occasionally be renewed. Many water-repellent sprays are available on the market, although their effectiveness is often only temporary. Our recommendation? Contact professionals who specialise in car cover maintenance. At SPECIAL COVERS, we also provide this service.
The final — yet equally important — characteristic of every outdoor cover is resistance to ultraviolet radiation (UV radiation). UV radiation, as a natural component of sunlight, affects nearly all textile materials. Prolonged exposure gradually degrades the material and reduces its overall strength. In practice, this means that if you purchase a cover without UV stabilisers or protective additives, the material may begin to deteriorate after only a few months of use. If UV resistance is not clearly specified for an outdoor cover, we recommend avoiding such products altogether. If the cover cannot protect itself, it cannot properly protect your vehicle either. Otherwise, you may soon find yourself investing in another cover again.
To summarise, the key feature of every car cover is the ability to allow moisture vapour to escape outward. Outdoor covers are designed for significantly harsher conditions and therefore require additional protective properties. Waterproofness and UV resistance are essential features of any high-quality outdoor car cover. Have you encountered other properties that you consider equally important when choosing a new cover? Fabric density? Highly elastic seams? There are many more. You can learn more in our article: Car Cover Buying Guide.
If you have any questions, please feel free to contact us. We will be happy to help.
