3 in 1 jackets are all part of the layering system. Layers are essential to keeping you warm and dry.
A 3 in 1 jacket comprises both a midlayer as well as a ‘hard shell’ or outer layer, which can be zipped together. This is known as ‘Interactive’ jacket, or marked simply as ‘IA’.
Interactive jackets secure into the midlayer via zips or hook points, which allow you to take them out or put them in with ease.
With an interactive jacket you have the following benefits:
- An outer layer (hardshell) that repels water and wind that can be worn alone in wet weather.
- A mid layer (usually fleece based) that insulates you. This can be worn under the hard-shell.
- Zip out capabilities so the fleece can be worn alone in good weather.
3 in 1 Jackets are a good way of insulating yourself against the cold in all 4 seasons.
Interactive jackets are also an excellent value for money purchase as they are suitable for all seasons and for most activities.
The hardshell layer of the jacket (or the 'outer') is designed to be highly technical, usually offering full waterproofing and windproofing protection via the use of a coated membrane whilst the insulating midlayer traps in warmth.
To read more, see our Guide To Waterproofing and our Guide To Windproofing.
Breathability is key to an insulated jacket, because you are layering. The excess layers need to be both warm and insulating, as well as breathable.
Any sweat that you produce should move through your baselayer, through the midlayer and to the outside of the jacket where it can evaporate, keeping you dry and comfortable.
Breathability is achieved by the jacket construction, usually with the use of a pore based membrane, that allows fabrics to be both waterproof/windproof, as well as breathable. GORE-Tex is an example. The pores prevent rain droplets from entering, but are small enough to let moisture vapour and sweat be released.
To learn more, read our Guide To Breathability.
The insulating layer (often known as a mid layer) is key to the 3 layer system and is the part of the system that will provide insulation for your core area, and help your base layer to move any moisture away from your skin to form a breathable system that will keep you warm, yet nnot overheating.
Fabrics vary for midlayers, but typically fleece is used.
Fleeces are created from polyester yarns, but they can be blended with natural or manmade synthetic fibres dependent on how they need to feel and perform.
Synthetics are generally a better choice for breathability and Nylon and polyester are typically used, although many brands have their own manmade fibres. These synthetics dry extremely quickly and are easy to maintain.
Whereas natural fibres such as cotton feel comfortable next to the skin when dry, they are incapable of wicking away moisture, and instead hold it like a sponge, making the garment heavy and uncomfortable.
Synthetics are the best choice for midlayers, although natural fibres can be blended with these synthetics to create hybrid fabrics that are soft to the touch, yet technical enough to provide a barrier from moisture.
Midlayers in 3 in 1 jackets usually incorporate a lot of stretch for a comfortable and adjustable fit, usually using a percentage of Elastane, Lycra, Spandex, or a similar flexible material.
Wool can also be used in baselayer creation, most typically merino wool from merino sheep. This is a wool created from ultra light fibres so it can be both warming, as well as breathable.
As opposed to synthetics which wick moisture away by pushing vapour to the outer surface, wool absorbs moisture, which is then evaporated. Wool does get heavier, due to this absorption, but will evaporate moisture in much the same way as a synthetic garment. However, wool is a more expensive alternative to synthetic fabrics.