After having equipped yourself with a first layer of underwear and a mid-layer such as a fleece, the choice of the third layer is decisive for the skier or hiker.
Depending on your practice, this jacket will be more or less protective (waterproof) or light (breathable). The performance of a third layer is therefore determined by two main indicators:
- Impermeability
- Breathability
Depending on your practice, other criteria may also be considered such as:
- Lightness and compression
- Heat input
Each sporting activity requires specific protection which varies according to its intensity and the conditions of practice. A third layer must imperatively be waterproof and breathable to ensure the general effectiveness of the 3-layer system.
| Waterproofability | Waterproofing is the jacket's ability to prevent water from getting inside. It varies according to the technical nature of the jacket and is measured in Schmerber (1 Schmerber = 1 water column of 1 mm). It is make by the use of a coating which makes it possible to stay dry under a light rain or by a liner which resist a much more sustained water pressure. For those who practice outdoor activities occasionally and in good weather, a moderately waterproof jacket will be sufficient. For those who go out whatever the weather, a perfectly waterproof jacket is essential: minimum 20,000 mm Schmerber. |
| Breathability | Breathability is the ability of a jacket to expel wetness away from the body. It also varies depending on the technical nature of the jacket. Its level is assessed with the MVTR unit, which is expressed in g / m² / 24 h (amount of water that the fabric lets through in 24 hours). Evaluated from 5,000 to 30,000, this number increases with breathing capacity For those who practice an intense activity such as mountaineering and ski touring, it is strongly recommended choosing a highly breathable jacket: minimum 20,000 g in order to avoid condensation in the clothes. |
| Lightness and compressing | The lightness of the third layer is also an element to consider. The more intense an activity, the more lightness will facilitate movement, as is the case in mountaineering or ski touring. The lightness of the jacket is conditioned by the thickness of its fabric and its membrane. Beware of jackets that are too light for mountaineering: lightness = fragility, and therefore sensitivity to friction from backpacks and rock. The lightness of a garment often rhymes with its ability to compress. Thus, the lighter and thinner a jacket, the easier it will be to put it into the bottom of a bag. A detail much appreciated by mountaineers and hikers who may encounter very different conditions during their expeditions. |
| Insulation | Some third layers have an insulating layer to enhance the effect of the second layer. The more dynamic is the practice, the less insulation should be added to not be too hot. These jackets are perfect for alpine skiers or flat hikers who practice a less intense activity. For other activities, it is rather advisable to increase the thickness of the mid-layer for a greater heat input. |
In summary :
For those practicing an intense activity in any weather: Impermeability / Breathability = 20,000 / 20,000
The best membrane being is the one made by the Gore-Tex brand.
For those practicing a less intense activity but in cold weather: Impermeability / Breathability = 10,000 / 10,000 OR 20,000 / 20,000 + light thermal insulation
The Gore-Tex membrane or the membranes made by the clothes brands are ideal for this kind of practice and allow a more interesting price.
For those practicing an occasional activity and in good weather: Impermeability / Breathability = 10,000 / 10,000
The membranes of the brands are ideal for this kind of practice and allow a more attractive price.
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