Buying a waterproof jacket: everything you need to know

Waterproof jacket and hardshells

A waterproof jacket is a type of hardshell jacket, which is why we use the terms synonymously. Hardshell jackets make up the outermost clothing layer. They protect you from wind and rain, but they don’t keep you warm – you’ll need to wear layers underneath your jacket for that.

Softshell jackets are different: the material feels soft (hence the name), they’re more breathable than waterproof jackets – but they’re not waterproof, only water repellent. Depending on your activity, layering is recommended. Use a softshell or a light down jacket to add a insulating layer over thermal underwear and wear a waterproof jacket on top.

Breathability

There are two different ratings for membrane breathability: the MVTR value and the RET value.

• MVTR measures how many grams of water vapour per square metre pass through a material in 24 hours. The higher the value, the more breathable the material. A fabric is considered breathable from a value of 3,000 g/m2/24h. If you’re wearing the jacket for strenuous activities where you’re sweating heavily, a more breathable hardshell (10,000 g/m2/24h) is the better choice.

• The RET value measures how much resistance a material has against water vapour. The lower the value, the more breathable the waterproof jacket is. High breathability is between two and six. For everyday life or moderate physical activity, you’d also be well served by a hardshell with a value between six to ten.

You’ll only benefit from the full breathability if the layers underneath your waterproof jacket are also functional; the water vapour from your body will then be able to reach the outside, layer by layer. This means that your underwear and insulating layer must also be breathable. For example, if you’re wearing a cotton shirt as the first layer, it will absorb sweat but not wick it away. Underwear made from another material, such as Merino wool, is more suitable.

Two-layer, two-and-a-half-layer and three-layer jackets

Fit

A waterproof jacket should lie close to your body, but give you freedom to move. And don’t forget that you might wear a fleece or down jacket as a second layer under your hardshell jacket during your adventure. Even so, it shouldn't feel too tight.

Features

GORE-TEX®: The most important facts about the membrane

The GORE-TEX© membrane is a microporous fabric with 1.4 billion pores per square centimetre. These pores are about 20,000 times smaller than a water droplet, but about 700 times larger than a water vapour molecule. That’s why GORE-TEX© is waterproof from the outside, but has a breathable membrane from which sweat can still escape. Water can penetrate the membrane if high pressure is applied. For example, a heavy backpack can push water through the membrane at the shoulders. A substance on the membrane also prevents body oil or insect repellent from penetrating the pores and clogging them.

Waterproof jackets with GORE-TEX© generally have the same waterproof membrane. Depending on the product, however, they are stitched or glued to other fabrics. The combination of the outer fabric and lining determines the breathability and durability of the waterproof jacket, and thus also which adventure it’s suited for.

You can find an overview of different GORE-TEX© fabrics here.

Water column and waterproofing

The water column indicates the pressure at which a substance or membrane allows water to pass through. This is tested with a standardised cylinder with a millimetre scale, which is filled with water. The fabric is stretched underneath and then the cylinder is filled with water until the material weakens. The result and corresponding value of the water column are given in millimetres. The higher the number, the more waterproof the fabric.

An overview of water column values:

• Less than 1,500 mm: water repellent to water permeable

• Over 1,500 mm: the fabric is considered waterproof. A water column of 1,500 mm is usually too low for a waterproof jacket. Exposed areas like your shoulders will most likely get wet

• 4,000 mm: waterproof without additional pressure, e.g. from a backpack

• From 10,000 mm: waterproof, even if wearing a backpack that puts additional pressure on the shoulders

Even with a high water column, you probably won’t stay completely dry in any garment – sooner or later water will get in through the openings on the hands and neck.

Waterproof jacket care

Wash your waterproof jacket regularly. It’s important that the jacket is regularly cleaned of dirt, sweat and body oil. This will keep your jacket breathable and waterproof for longer.

The care label in your jacket gives you precise instructions on how to wash and waterproof your jacket. As a general rule, use a special detergent for washing, never a heavy-duty detergent or fabric softener, which could destroy the membrane. Choose a gentle wash cycle with a reduced spin rate and additional rinse cycle to avoid detergent residues. Depending on the membrane, you should tumble dry the jacket. This helps to refresh the water-repellent function. You don't have a dryer? Let the hardshell air dry. Then place a thin towel on the jacket and iron it on a low setting. Waterproof your jacket according to the instructions on the care label and the product instructions. Hardshells should generally receive fresh waterproofing after about two to three washes.