How To Rate Your Waterproof Outerwear! – What Do The Numbers Mean?

Protection from the elements while enjoying your favorite outdoor activity is vital for an enjoyable experience. Buying quality waterproof-breathable outerwear helps you achieve that goal. Jackets and pants with waterproof and breathable fabrics are the first steps to staying dry so that you can focus on having fun, no matter what the weather says. Companies use many types of water-resistant fabrics and materials to make their outerwear waterproof; keep reading, and we’ll help you understand everything you need to know to pick the right outerwear. 

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What Does Waterproof Rating Mean? 

Manufacturers typically describe fabrics’ waterproof and breathability ratings using two numbers, often separated by a backslash. The first number is waterproof; the second is breathability. The origins of these ratings are in a scientific lab (described below), not the outdoors, but the bottom line is simple – the higher the rating, the more waterproof and the more breathable the jacket or garment is. Some manufacturers report waterproof ratings in PSI (Pounds per Square Inch) rather than millimeters, with a conversion rate of 704 mm = 1 PSI.

Fabric Waterproof Ratings

Waterproof Rating	Breathability Level	Conditions
0-5,000 mm	Low	Light Rain, Dry Snow
6,000-10,000 mm	Moderate	Light Rain, Average Snow
11,000 – 15,000 mm	Moderate-High	Moderate Rain, Average Snow
16,000 – 20,000 mm	Moderate-High	Heavy Rain, Wet Snow
20,000 – and up mm	High	Heavy Rain, Wet Snow

What Is The Science Of Waterproof Rating?

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

How Do They Make Fabric Waterproof and Breathable? 

Waterproof breathable fabrics consist of an outer layer called the “face fabric,” traditionally 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 coated with a solution called DWR (Durable Water Repellent), so it doesn’t soak up water. For colder wear garments, a layer of insulation is added for warmth.

Keeping the water out is accomplished by a layer called the membrane, which has tiny holes too small to let liquid water enter but large enough to allow water vapor to escape. Contamination with oil, sweat, and chemicals can cause membranes to lose their ability to keep out water; an ultra-thin layer of Polyurethane protects the membrane.

A lining is bonded to the inner surface for comfort. Modern waterproof breathable fabrics have come a long way, and most are highly waterproof at any price point and offer outstanding breathability.

Why Isn’t My Outerwear Completely Waterproof? 

You probably wouldn’t want to wear it if it was. A rubber raincoat is completely waterproof and may be ideal for standing in a downpour. If you wanted to do any activities in this rubber raincoat, you would be wet in no time from perspiration. It would be best if you had a garment with an excellent active shell to protect from rain and snow on the outside and let water vapor (warm perspiration) escape from the inside.

All outerwear designed for active use has degrees of water resistance but will eventually leak, given enough water, time, and pressure. Manufacturers define “waterproof” according to different standards, and testing is not standardized. Understanding the rating system is essential to choose the best outerwear for your activity. 

Why Does My Waterproof Outerwear Seem To Be Losing Its Effectiveness? 

Over time your waterproof garment will need treatment; follow your manufacturer tag for cleaning recommendations. DWR aftermarket treatment products will allow you to recondition your garment and bring its effectiveness back to life.

If your garment is not heavily soiled, I recommend treating it with a spray-on product; Nikwax or Gear Aid both make suitable spray treatments. You can also find wash-in products from both companies.

Reminder on wash-in use, read your garments care tag to see that it would be safe for washing machine use. I have a pair of waterproof insulated flotation bibs for ice fishing designed to be hand-washed only.

Final Thoughts: Is GORE-TEX The Only Waterproof Option? 

For years products that had GORE-TEX to them were the top waterproof and breathable garments to own. Many manufacturers have found ways to compete with the waterproof and breathability elements that many of us are accustomed to using GORE-TEX. Here is a list of those competing companies that you can look for in your garment:

• Polartec®
• DryVent® (Formerly Hyvent®)
• H₂No®
• PreCip™
• Pertex®Shield+ / AP
• Dermizax™​

Another feature to look for when reviewing your garment is to see if it has sealed seams. 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 they are typically sewn and taped.

Today’s technology in outerwear can help extend your time in the field and get you out in the outdoors more throughout the year.

Celebrate The Experience!