The ski layering system, explained properly

Layering is explained badly almost everywhere, usually as a list of garments. It is more useful as a list of jobs, because once you know what each layer is for you stop buying a fourth jacket to solve a problem the second one created.

Layer one: move moisture

The base layer sits against the skin and its only job is to move sweat away from it. Skin that stays wet loses heat far faster than skin that stays dry, which is why this layer decides more about how cold you get than the insulation above it.

Weight is quoted in grams per square metre and is the number to shop on. Roughly 150 gsm is light, suited to touring, spring days and anyone who runs hot. 190 gsm is the all-round resort choice. 250 gsm is genuinely warm and belongs on a cold chairlift day rather than on anything where you generate heat continuously. Pair a midweight top with a lighter bottom, because legs generate a lot of heat inside insulated pants.

Merino keeps insulating when damp and does not develop a smell over multiple days, at a higher price and a shorter life. Synthetics dry faster, cost less and last longer, and smell after a day. Blends split the difference and are increasingly the sensible default. Cotton is the only genuinely wrong answer: it absorbs water, holds it against the skin, and stops insulating entirely once wet.

<!-- gift-guides-xlink -->

Layer two: hold warm air

Insulation works by trapping air. Everything else about a midlayer is a question of how much air it traps, how much moisture it lets through while doing so, and what happens when it gets wet.

Grid fleece is the most useful single piece in snow sports. The waffle grid on the inside face traps air in the squares and moves moisture along the channels, so it keeps working while you are working. If you own one midlayer, own this.

Synthetic insulated pieces are the ski-specific answer for real warmth, because skiing is a wet activity. Snow melts on you, you sweat under a shell, and a soaked down jacket is a wet bag of feathers with no loft. Synthetic keeps most of its warmth damp, which is why nearly every ski-specific insulated piece uses it.

Down is warmer per gram and per litre packed and belongs where it stays dry: a parka you put on at the car, in a hut, or under a shell in genuinely cold dry conditions. The full argument is in down against synthetic.

The distinction nobody explains is air permeability. A breathable, air-permeable insulated piece can be worn while you are working and dumps moisture as you generate it. A windproof puffy cannot, and turns into a sauna on a climb. For touring you want an active insulation piece for moving and a genuinely warm belay-style parka that lives in the pack.

Layer three: keep the weather out

A shell keeps wind and snow out and lets moisture escape. Construction decides durability: a two-layer garment bonds the membrane to the face fabric and hangs a separate liner inside, which is cheaper and bulkier; a three-layer garment bonds face fabric, membrane and backer into one, which is lighter, more packable and far more durable under pack straps and ski carries.

Waterproofing and breathability are quoted as a hydrostatic head in millimetres and a vapour transmission rate in grams. Around 10,000 by 10,000 is the practical floor for resort skiing and 20,000 by 20,000 is a genuinely capable shell. Both numbers matter less than pit zips, which vent more moisture in a minute than any membrane does in an hour, and less than fully taped seams, which are the difference between a jacket that keeps snow out and one that leaks at every stitch line.

Why the shell plus midlayer beats an insulated jacket

An insulated jacket is warm at one temperature. You cannot take the insulation out, so a spring day means either sweating or leaving the jacket in the car. A shell over a separate midlayer covers roughly a forty degree range for similar money, and the shell outlives several midlayers because it is the piece that does not compress and wear.

That single switch is the most useful clothing decision on this site, and it is the upgrade the beginner resort build recommends making first when the starter jacket wears out. The case for the insulated jacket is simplicity, which is a real argument for somebody who skis four days a year in one climate.

The two activities want opposite things

A resort day is a heat cycle: you generate heat on the descent and lose it sitting still in the wind on the lift, roughly half the time each. So insulation is worn constantly and venting is done with pit zips rather than by removing layers, which is impractical on a chairlift.

A touring day is not a cycle. You generate heat continuously for hours on the climb, then stop dead, then descend fast. The discipline is to start the climb slightly cold, in a light base layer and a wind shell, and to put insulation on at every transition rather than before it. Everything you sweat into on the way up becomes ice on the way down, and that is not a comfort issue in genuinely cold conditions.

Extremities are where days are actually lost

Cold hands and cold feet end more ski days than cold torsos, and neither is usually solved with more insulation. Cold feet in ski boots come from compressed circulation, so a second sock or a thicker one makes it worse by reducing volume in a boot that already fits. One thin snug over-the-calf sock, a properly fitted shell, a supportive footbed, dry liners and loosening the buckles on the lift are the actual fixes.

For hands, mittens are meaningfully warmer than gloves at the same insulation because the fingers share heat, at the cost of dexterity. Carry a second pair, always. For touring, carry a light glove for the climb and a warm glove or mitt for the descent, because one pair for both means either a soaked liner on the way up or cold hands on the way down.

Care, which is most of what makes a system keep working

Wash your shell more often than you think. Body oils and dirt block breathability, and a jacket that has stopped breathing feels like a jacket that has stopped being waterproof. Use a technical wash rather than detergent, never fabric softener, and tumble dry warm to reactivate the durable water repellent finish. When water stops beading after that, apply a wash-in DWR treatment.

Wash merino cool with a wool-safe detergent and dry it flat or on a line, because a hot tumble dry shrinks and felts it. Wash synthetic insulation with a technical wash and tumble dry low to restore loft, and store insulated pieces uncompressed, because long compression permanently kills loft in both down and synthetic.

Related

Run conditions through the layering calculator, or use the printable layering chart. The roundups for base layers, midlayers, shells and socks and gloves cover the pieces at each tier.

Touring is where layering stops being about warmth alone and becomes about weight, because you carry every layer you are not wearing. If you are trying to get a touring pack down, the gear list builder on UltraLightSetup weighs a kit item by item, which is the fastest way to find where the ounces actually are.