Waterproof and Breathable Ratings on Outerwear


Modern day sports outerwear has evolved to accommodate a wide range of weather conditions and activities.  Outdoor apparel brands today make their own proprietary water/breathable materials, while also incorporating well-known materials like Gore-Tex and eVent into their lines.  There are also a variety of waterproof and breathable ratings on outerwear that offer a different levels of protection from the elements that we’ll be looking at shortly.

In the days before materials like Gore-Tex came on the market, most garments were coated with a rubber or waxed layer to keep precipitation from soaking in. But, these rubberized fabrics didn’t let body heat and the subsequent sweat it causes to escape.  The result was you were getting wet from the inside even though the rain and snow stayed on the outside.

Being wet in cold, cool or windy conditions can cause hypothermia to set in very quickly, and that can, and will, incapacitate or even kill you if you can’t get to shelter soon enough.  So the whole idea behind waterproof/breathable materials is to regulate the environment inside the garment while keeping the precipitation and wind from penetrating.

The ratings given to waterproof/breathable outerwear indicate the degree to which they keep moisture from entering the fabric (the first number) and the degree to which they allow vapor and heat to pass through from the inside (the second number).  On the jacket or pants tag they usually read like this as an example: 20K mm, 20 g/m2.  The waterproofness is measured by the amount of water pressure the fabric can withstand before the moisture begins to force its way through it and is expressed in thousandths (k) of millimeters (mm).  The breathability is measured by calculating how many thousands (k) of grams of vapor per square meter of material (g/m2) is allowed to be transmitted from the inside of the garment to the outside where it can easily evaporate.



Waterproof Ratings 

  • 5,000 Waterproof Rating: A waterproof rating of 5,000K or less will offer little waterproofness. You’ll be fine wearing 5k/5k outer in sunny, cool and dry conditions but if it is raining hard then you will probably get wet.
  • 10,000 Waterproof Rating: A waterproof rating of 10K will offer better waterproofing than the 5K and should keep you dry in light rain and drizzly conditions.  It should also work fine in normal snowfall that is not excessively wet.
  • 15,000 Waterproof Rating:  A waterproof rating 15K will handle any weather condition except drenching rains or really wet blizzard conditions.  15K waterproof gear will keep you dry in most backcountry conditions.
  • 20,000 Waterproof Rating:  A waterproof rating of 20K will keep you dry in the most extreme rain and snow events.  20K waterproof gear will protect you the best in all conditions.

Breathability Ratings

  • 10,000 g/m2:  Most outerwear with a 10K breathability rating will allow the release of some of the moisture your body produces.  On super cold days this is fine because you want to retain as much heat as possible.  But if you are exerting yourself you may feel overheated and begin to sweat.  So 10K breathable garments will be fine for most average activities on the ski area or flat land hiking.
  • 15,000 g/m2:  Outerwear with a 15K breathability rating will release heat and vapor in most high-level activities where you are expending a lot of energy.  If you ride at the ski area and spend time in the backcountry hiking your lines then 15K will help you stay dry on the inside in most conditions.
  • 20,000 g/m2:  Outerwear with a 20K breathability rating will readily dump most of the heat and water vapor your body produces even while engaging in the most high-energy activities.


Taped Seams – Durable Water Repellant (DWR)

Two other factors involved in the making of technical outerwear include taped seams and DWR coating.

Taped seams are strips of waterproof tape that cover the holes made by stitching the various pieces of the jacket or pants together.  Without taped seams water will enter into the garment through the needle holes.  Taped seams are heat molded onto the garment so that they move easily in all directions without coming off even under a lot of stress.



DWR coating is applied to the outside of the garment.  Its purpose is to make water bead up and roll off the garment.  The longer water droplets stay on outerwear the higher the chance they will get absorbed into the fabric.  DWR act as a first layer of defense to prevent this from happening.  The application does not last forever so the user will need to reapply a fresh coating when they notice the outside of the garment absorbing a lot of water from rain or wet snow.

If you need help figuring out what waterproof-breathable jacket and pants would best fit your needs talk to someone at your local shop that sells outerwear.  Most shops have a good range of clothing that covers everything from resort riding and easy hikes to backcountry activities that require you to be prepared for more extreme weather conditions.


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