Waterproof Ratings
WATERPROOF RATINGS AND BREATHABILITY GUIDE
You like the outdoor elements, no matter the season you want to stay warm and dry whilst you play, hike, ride, ski, snowboard, walk, or cycle. Queue the waterproof breathable fabric – key to keeping dry and comfortable in mother nature.
| Waterproof Rating (mm) | Resistance provided | What it can withstand |
| 0-5,000 mm | No resistance to some resistance to moisture | Light rain, dry snow, no pressure |
| 6,000-10,000 mm | Rainproof and waterproof under light pressure | Light rain, average snow, light pressure |
| 11,000-15,000 mm | Rainproof and waterproof except under high pressure | Moderate rain, average snow, light pressure |
| 16,000-20,000 mm | Rainproof and waterproof under high pressure | Heavy rain, wet snow, some pressure |
| 20,000 mm+ | Rainproof and waterproof under very high pressure | Heavy rain, wet snow, high pressure |
WHAT DO THE NUMBER RATINGS (10k,20K) ACTUALLY MEAN?
Manufacturers typically describe the waterproof breathability of fabrics using two numbers. The first is in millimeters (mm) and is a measure of how waterproof a fabric is. In the case of a 10k or 10,000 mm fabric, if you put a square tube with inner dimensions of 1” x 1” over a piece of fabric, you could fill it with water to a height of 10,000 mm before water would begin to leak through. The higher the number, the more waterproof the fabric.
The second number is a measure of how breathable the fabric is - this is normally expressed in terms of how many grams (g) of water vapor can pass through a square meter (m2) of the fabric from the inside to the outside in a 24 hour period. In the case of a 20k (20,000 g) fabric, this would be 20,000 grams. The higher the number, the more breathable the fabric is.
IS OUTERWEAR COMPLETELY WATERPROOF?
The truth is that all outerwear designed for active winter sports has various degrees of water resistance, but will eventually leak given enough water, time and pressure. Manufacturers define “waterproof” according to different standards. A rubber raincoat is completely waterproof, and may be the ideal garment for standing in a downpour, but if you tried to ski or snowboard in it, you’d be wet in no time from your own perspiration. The trick is to balance protection from rain and snow on the outside with the ability to let water vapor (warm perspiration) escape from the inside.
HOW DO THEY DO IT?
Waterproof breathable fabrics are made up of an outer layer called the “face fabric”, this is usually made of nylon or polyester, then a laminated membrane or coating, (made of ePTFE - expanded Polytetrafluoroethylene, also known as Teflon® or PU Polyurethane). The purpose of the face fabric is to protect and look stylish and have a nice hand feel; it’s not waterproof but is treated with a solution called DWR (Durable Water Repellent) so it doesn’t soak up water – kind of like putting wax on a car – the water beads off it – as it does on our jackets.
What Rating do I need for my outerwear?
We recommend a minimum waterproof rating of 5,000 mm for ski and snowboard outerwear. If you hit the mountains primarily in cold and clear conditions and take regular lodge breaks this level of protection is sufficient. Our Buyers at Snowbiz pride ourselves in providing premium products to our customers and do not offer anything below this 5K waterproof rating.
Outerwear rated between 5,000 mm and 10,000 mm is a better choice for riders who spend long days out and ski or snowboard in all weather conditions. Those hitting the hills in wetter climates (Australia/NZ) should look for waterproof ratings in the 10,000 mm to 20,000 mm range or better. If you spend a good percentage of your time in the backcountry or hiking or skinning to remote locations, breathability is equally as important as waterproofing – look for outerwear where both waterproofing and breathability are in the 20,000 k range. When you work hard, you outerwear needs to work even harder.
As you might expect, higher ratings in both categories will usually mean higher prices. Remember that while a 20,000 mm rating may sound impressive, a hard day of riding in wet conditions with the added pressure of wind, sitting, and falling puts even the most waterproof fabrics to the test.
HOW BREATHABLE DO I NEED MY GEAR TO BE?
Ask yourself – What is your level of activity going to be. A layer of warm, moist air between your body and your jacket/pant can mean warmth as long as your under layers work effectively and don’t become saturated with moisture.
If all your riding is lift-based, you don’t hike to out, and you take regular breaks in the lodge where you remove your coat, a breathability rating of 5,000 to 10,000 grams will be fine. If you do a lot of high energy movement or riding where you often break a sweat getting to your destination or returning to the inbounds area, look for breathability in the 10,000 to 15,000 gram range. Hardcore adventure freaks who push the limits all day every day should look for garments with breathability in the 20,000 plus range.
WHAT IS SEAM SEALING?
Seam sealing, sometimes referred to as seam taping, covers the tiny holes made by the needle in the sewing process so they don’t leak, using a heat application of thin waterproof tape. Sometimes seams are bonded together using glue or heat, but typically they are first sewn then taped. Garments can be either “fully taped” or “critically taped” – the difference is that a fully taped garment has every seam taped, while a critically taped one has tape only on high exposure areas like the neck, shoulders, and chest. Without adequate seam sealing you’ll get wet even with the best waterproof/breathable fabric.
WHAT IS DWR?
DWR stands for Durable Water Repellent. Almost all outerwear exterior fabrics are treated with some sort of DWR. It’s meant to keep the fabric from becoming saturated with water and adding weight. DWR causes water to bead-up and roll off the fabric and is affected by abrasion, dirt and body oils. This is why after some use, a garment will appear to no longer be waterproof. This isn’t the case, though - it likely means the DWR needs to be refreshed by simply washing the garment .The factory DWR treatment will eventually wear off, and wash in products/sprays are available in store or online to re-condition your waterproof/breathable garment after washing – try one of these if you notice water soaking into the face fabric of your Waterproof/Breathable garments and you have already attempted to refresh the DWR by cleaning your outerwear.
WHAT IS GORE-TEX®?
GORE-TEX® fabrics are created by laminating a GORE-TEX® membrane to high performance nylon and polyester face fabrics. They come in several different grades, GORE-TEX® Active, and just regular GORE-TEX®. GORE-TEX® garments are fully seam sealed and feature a “GUARANTEED TO KEEP YOU DRY®” promise. Although many laminates are waterproof, a GORE-TEX® membrane is capable of maintaining an extremely high level of waterproofness while staying very breathable thanks to billions of microscopic pores that let water vapor out and prevent liquid water from entering.
Electron microscope photography of GORE-TEX® membrane
While some people refer to all waterproof/breathable fabrics as “GORE-TEX®,” it’s a proprietary product and technology of the W. L. Gore Corporation. The W. L. Gore Corporation is zealous about upholding the reputation and performance standards of GORE-TEX® outerwear, and maintains a strict set of rules for any company making a GORE-TEX® garment. You don’t just buy their fabric and send it off to China for production. They require waterproof, breathability and durability testing of every garment in both design and manufacturing stages, mandate use of GORE seam tape and taping machines, and insist on current factory certification for any facility building GORE-TEX® jackets, pants, gloves or shoes.
OTHER WATERPROOF BREATHABLE BRANDS
The outdoor fabric industry is currently experiencing a surge in new product development that competes directly with GORE-TEX®. Many products on the market in the last few years are pushing the envelope with new technology and are extremely waterproof and breathable without the high price point. They are targeted at the everyday person who wants value for money without compromising function or quality.