Waterproof vs. Water Resistant Fabrics
When you see “waterproof” and “water resistant” in descriptions of fabrics here at Sailrite, you might be thinking to yourself that those two terms seem interchangeable. While they do seem incredibly similar, they convey very different meanings and should be taken into consideration when choosing an outdoor fabric.
Fabrics marked waterproof will always repel water. They do not let water soak into them under any conditions, even if the fabric is old. These fabrics are mostly vinyl, vinyl-coated or laminated.
Fabrics that are water resistant have been treated to repel water from their surfaces, but if the coating is old or water is pooling on top of the fabric they can soak through.
Waterproof looks like the way to go all the time then, right? Well, not quite. One of the biggest tradeoffs of a waterproof fabric is breathability. Waterproof fabric, by its nature, doesn’t let anything through its surface, and this includes air. This isn’t a big deal in some applications like awnings or speedboat interiors, but can be problematic for covers.
When air and moisture get trapped underneath a cover, mold and mildew and grow and cause serious problems. If you want to cover your boat, for example, in a vinyl or laminated waterproof fabric, we recommend adding a vent, like the Boat Vent II or the Vent Aire Ventilator, to prevent this moisture build up.
If you value breathability more than full waterproofness, you can still use breathable, water resistant fabrics for covers. If they have a good pitch (from poles or the angle of an awning) the water will run right off these water resistant fabrics and they won’t require vents—although many people like to vent these covers, too.
There are also, of course, applications where waterproofness doesn’t matter that much. Patio cushions and pillows are a great example of this. Water resistant fabrics are desirable here because they will protect from the elements but the breathability makes them a more comfortable seat. And, since cushions can be brought inside and out of the rain, a fully waterproof fabric probably isn’t necessary.
In conclusion, while truly waterproof fabrics are great for protecting your boat, patio furniture and more, they can cause problems as covers if not properly vented. Water resistant fabrics offer much better breathability but need to be tented in a cover application. So, it’s up to you to weigh the pros and cons for your application and, of course, your personal preferences. But now you have to tools to make the best decision for your next project.
For more information on what to consider when choosing an outdoor fabric, refer to our Outdoor Fabric Selection Guide or our How to Choose an Outdoor Fabric post (#X-HT-300030).
What's most important to you when choosing a cover fabric? Share your opinions in the comments.