Waterproof & Breathability Ratings for Winter Garments

As the colder temperatures start to make an impact on our morning commute or if working outdoors for extensive periods of time, it becomes a necessity to source the right winter garments to make living and working during extreme weather as comfortable as possible. In particular when wet weather is imminent, the right jacket can make all the difference, so knowing the technical differences between Waterproof Ratings & Breathability and how efficient the garment is when exposed to the elements is key for a comfortable experience during winter. Also checking for important features such as seam sealing is important to the efficiency of a garment. This is the process of treating the stitch holes and seams in garments made from waterproof fabric to prevent them from leaking when it rains or snows to achieve maximum waterproofness.

Fabric Waterproof Ratings

How are Waterproof Ratings Determined?

Waterproof ratings are determined by the clothing manufacturer or fabric producer, with testing done either by independent laboratories or in-house. There are a number of different testing protocols in use, but most involve the equivalent of placing a 1” x 1” square tube over the fabric and determining how high (in millimeters) a column of water you can suspend over it before it starts to leak. Some manufacturers have developed their own testing methods that involve adding pressure to the process to simulate the effects of wind.

While waterproof ratings are becoming more standardized, remember that different labs may test or report differently, and may come up with different results even with two pieces of fabric from the exact same roll, so take the numbers with a grain of salt. Keep in mind that some manufacturers report waterproof ratings in PSI (Pounds per Square Inch) rather than millimeters, which has a conversion rate of 704 mm = 1 PSI.

Illustration of a waterproof breathable membrane

How are Breathability Ratings Determined?

Like waterproof ratings, breathability ratings are determined by both manufacturers and independent labs, but the testing methodologies are quite diverse and almost impossible to compare with each other.

Results can vary wildly based on test, temperature, humidity and pressure and are not standardized from brand to brand, or test to test. Most testing doesn’t reflect real world winter conditions, like near freezing outside temperatures with high relative humidity. Since manufacturers seldom reveal the actual test used, and are probably keen on reporting the highest possible figures to promote sales, it’s best to read these numbers with the eye of a skeptic, but generally within a given brand or family of fabrics it’s safe to say more grams is more breathable (if a company grades breathability on an RET scale – Resistance to Evaporative Heat Transfer – a lower value is better).

How Waterproof a Garment do I Need?

Jackets and clothing with lower waterproof ratings are better suited for fair weather, low-moisture activities. Clothing and gear with higher waterproof ratings are ideal for people who need gear that will perform when the weather turns sour. People who wear backpacks often may also want to consider outerwear with higher waterproof ratings as the straps put pressure on the jacket and may force moisture through gear that has a lower waterproof rating. An intense, high-exertion day of activity in wet conditions with the added pressure of wind, sitting, and falling can put even the best-rated waterproof fabrics to the test.

We recommend a minimum waterproof rating of 5,000 mm, or 5k, for ski and snowboard jackets and snow pants. If you ride primarily in cold and clear conditions and take regular lodge breaks, this level of protection could be fine, but anything less and you stand a good chance of getting wet and cold in a storm. Clothing rated between 5,000 mm and 10,000 mm (10k) is a good choice for riders who spend long days out and ski or snowboard in any weather conditions. Avid skiers and snowboarders, especially those in wetter climates, 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 becomes equally as important as waterproofing – look for outerwear 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. It is money well spent.

Waterproof textile fabric and zipper for outdoor apparel

How Do They Make Fabric Waterproof & Breathable?

Waterproof breathable fabrics consist of an outer layer called the “face fabric”, usually made of nylon or polyester, and a laminated membrane or coating, usually made of ePTFE (expanded Polytetrafluoroethylene, also known as Teflon®) or PU (Polyurethane). The purpose of the face fabric is to protect and look stylish; it’s not waterproof but is treated with a solution called DWR (Durable Water Repellent) so it doesn’t soak up water. Sometimes a layer of insulation is added for warmth.

The job of keeping the water out is left to the membrane, which has tiny holes too small to let liquid water enter but large enough to allow water vapor to escape. Since contamination with oil, sweat and chemicals can cause PTFE membranes to lose their ability to keep out water, the membrane is protected by an ultra-thin layer of Polyurethane  Finally, a fine scrim or mesh is bonded to the inner surface for comfort in 3 Layer (3L) fabrics. 2 Layer (2L) fabrics receive a separate fabric liner, while 2.5 Layer fabrics use an abbreviated pattern screened on the inner surface to save weight. Modern waterproof breathable fabrics have come a long way and most are extremely waterproof at any price point, but outstanding gains in breathability in the past few years have redefined the market in high exertion outerwear.

Although the technical terms can be quite daunting when selecting the right garment, often it becomes a case of personal preference so take a moment when trying it on and make sure it suits your particular style and comfort requirements.

Please don’t hesitate to contact the team at JEM Promotional Products on (02)82051334 or enquiries@jempp.com.au so they can recommend the right garment for you and your team and be ready for whatever is in store this winter.