Waterproof Ratings – Snowboard & Ski Jackets - What the Numbers Mean
w waterproof the fabric of a snowboard or ski jacket is, is indicated by the waterproof rating. The higher the number, the more intensive rain can be before water will penetrate the fabric.
1,500 - 5,000
5,000 - 10,000
10,000 - 20,000
5000 mm We recommend a minimum waterproof rating of 5,000 mm for ski and snowboard jackets but only if you go out primarily in dry, clear conditions and take cover in a restaurant, bar or chalet as soon as the weather closes in.
If this describes you, you might ask “Why do I even need a waterproof jacket?” Well, you are likely to get covered in snow at some point during your holiday – from a fall, from a venture into the powder (planned or otherwise), from a passing chairlift or from snowballs! Snow melts pretty quickly when it discovers the warmth of your body! Also, it rains a lot more lower down the mountain than it does high up. Most people wear their ski and snowboard jackets around the resorts as well so you will never regret buying a waterproof jacket.
10,000 mm 10,000 should suffice for most people who spend all day on the mountain, especially if you stay on the piste and are happy diving into the occasional shelter should the need arise.
20,000 mm If you spend a good percentage of your time in the backcountry or hiking or skinning to remote locations, breathability becomes equally as important as waterproofing – look for a jacket with both waterproofing and breathability in the 20,000 plus range. As you might expect, higher ratings in both categories will usually mean higher prices but remember, 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.
What the Numbers Mean
Manufacturers submit their fabrics to specialist laboratories to perform hydrostatic head tests in which the fabric is pulled tight over a set of four sealed test tubes of water. The tubes are held upside down so the only way water can escape is through the fabric. All the tubes are identical (25mm in diameter) but they hold different quantities of water. The height of water is set at 1,500mm, 5,000mm, 10,000mm and 20,000mm. After 24 hours of soaking, the fabrics are then assessed to see if any water has penetrated. If no water has penetrated a fabric under the 10,000mm test tube, it passes the test. If the same fabric allows water to penetrate under the 20,000mm test tube, it fails the test so is awarded a rating of 10,000. Simple!
Do Not be Literal
10,000mm is the same as 10 meters but it does not mean you can immerse yourself in 10 meters of water for 24 hours and stay dry! Lab tests are lab tests and need to be translated for use in the real world. In the real world, the fabric does not sit neatly on the end of a test tube; instead it rubs up against your other clothing. Most people know that if you touch the wall or roof of a tent when it is raining, it leaks! The same applies to clothing. This is why you should refer to the handy table we have produced (higher up this page) and go for the best waterproof rating you can afford.