Protecting yourself against stormy weather in the mountains is essential and that’s the role played by the outer fabric of your jacket. There are different types of waterproof membranes, and their impermeability is measured on the Schmerber scale, which corresponds to the resistance to water in a standardized column (1 Schmerber = 1mm of water). Jackets can run anywhere from 5,000mm to 30,000mm Schmerber, and a jacket is considered waterproof starting at 10,000mm Schmerber.

3 layers or 2?

Perhaps you’ve heard of 2-layer or 3-layer jackets? This is a production technique that involves gluing different fabrics together to protect the waterproof membrane.

With 3-layer fabric, the membrane is protected by an interior and an exterior fabric.

With 2½-layer fabric, the membrane is protected by an exterior fabric and by a “print” on the interior.

With 2-layer fabric, the waterproof membrane is protected only on the exterior while the interior has an insulating lining.

In addition to the waterproof membrane, you’ll usually find a water-repellent treatment on the outer layer.