There’s nothing really fancy in the layering paradigm. In essence, it’s what many of us already do in the urban environment as a daily routine in response to changing conditions like getting into the office block: layer down one coat.

In the backcountry, there are additional factors though:

  • We must be self-reliant
  • We can only count on what we can carry

We need to find the most efficient layering system for the expected conditions. Actually, it’d be even better if it keeps efficient in the unexpected conditions too. This begs some deeper thought than just putting on/taking off the one coat.

Weight and bulk

Some hikers will care about weight/bulk more than others but there’s always a limit and weight/bulk is bound to be a factor in the search for the most functional layering system. Even the most laid-off non-planners will have this fact in their small print. Even the proud heavy-weighters know there is a limit.

Multi-functioning vs. Layering

Layering and multi-functioning are somewhat opposing concepts: multi-function negates layering. In an extreme case, a hypothetical layer that does it all would mean no layering is needed at all.

At the other end of the spectrum, layering’s potential is maximized when each item’s role does not intersect with the others’. This ideal would mean nothing is redundant. It is virtually impossible to get to that point but you can get very close by carefully choosing a set of very specialized items. I call this Strict Layering.

When trying to optimize carried weight, multi-functioning is a typical, apparently straightforward strategy: if an item fills several roles, there should be less items to carry… in actual use, it’s not that simple.

Roughly speaking, Strict Layering is heavier but a better performer. Throw some multi-function in the mix and you can save weight but the performance loss may get you to a point of diminishing returns.

Strict layering

The most efficient, wide spectrum system takes the Strict Layering paradigm. This is based on a set of multiple, highly specialized items that can work separately as well as together in many different combinations.

The power of this paradigm lies in its versatility. It can do anything from cold to warm, wet or dry and it’s real close to the best possible performer in all situations. Don’t be tempted to choose items that try to do many things, combine your unique pieces wisely instead. Trust the paradigm. Here is why…

A systematic approach to layering

Layering is a bit of an art and it may be real fun to play with.

The first step in the search for the ultimate layering strategy is to identify roles. These are the functions that must be covered by the clothing items. Role definitions should be precise and intersect each other as little as possible. They should be realistic.

After roles have been identified, the next step is finding actual clothing items that meet each role as closely as possible. If it is not possible to find the items that meet the roles, the latter will need to be redefined for a second iteration. On and on until everything falls into place.

Role definition

Roles must be defined so they meet the functionality we’d expect from the clothing system. I have come to identify the following roles:

Base

A second skin, it’s meant to be worn all the time. Any other item would layer over at least this one. It should provide sun protection and a nice, comfortable feel against the skin. Good moisture management is a must. As little insulative value as possible.

Active insulation

An insulation layer meant to be worn while active. It needs some structural integrity so the insulation is not easily crashed under pressure and resists moisture accumulation while keeping functional. Good moisture management is an absolute must.

Stationary insulation

Expectedly, an insulation layer meant to be worn while stationary. It should be lightweight and have low packed volume because it will be in the pack most of the time. It should have a high insulative value because we’ll need it when not active.

Shell

Outer layer to face the elements. It will be wind and bug proof and it must have good moisture management. Sized to hold all active insulation under it.

Waterproof

Outer layer to keep rain out. Some moisture management is welcome.

Sleeping base

A second skin, it must prevent skin contact with the sleeping bag, be comfortable against the skin, manage moisture well and be very light –it will be packed all the time.

Clothing items

Role definition is common to all body areas. Actual clothing system implementation will vary though depending on the area. Legs, for example, are quite forgiving: no vital organs and big muscles. Extremities are exposed and at the far end of the blood flow. The head is home to the most vital organ and the body will not skimp on resources to keep it comfortable.

The most complex case is found in the torso. It is the best area to use as an example for the best use of the layering paradigm. The torso will be most optimally dressed by covering each listed role with one piece of gear. This is what I use:

Base

A thin, light colored, long sleeve shirt is my universal base layer. It’ll be thin to provide as little insulation as possible. Making it more insulative would be going beyond its defined role! trying to force the shirt to do too many things: the base layer must work when it’s warm outside. If it’s cold, layer up.

The light color helps with its role as warm weather wear. If you want something dark to get warmer from the sun, use a different layer. You need this one to be good in the warmest situation possible.

The long sleeves may feel counter-intuitive after that last statement but you’ll need sun protection and sleeves are much lighter and cleaner than cream and you can always pull sleeves up if needed.

A short, chest deep front zip is very welcome: it helps with ventilation in warm weather and heat retention in cold conditions. The collar must embrace the neck when the zip is closed: this helps a lot with keeping warm because the neck is a huge heat sink due to the main blood flow in the area. Such a simple thing as this short zip extends greatly the comfort zone for the shirt.

This layer will be always on so its weight is not critical: the lighter is still the better but this applies most critically to anything in the pack. Typical weight of such an item is over 170 gr. (6 oz)

Millet Carline, true to description

Active insulation

A thin fleece in pullover fashion is perfect for this: it provides insulation, it doesn’t collapse when under load and it manages moisture extremely well. It’ll be very welcome whenever it’s too cold for the other active layers (base and shell) alone but it doesn’t need to be thick because we’ll be active. Fleece has excellent moisture management, pumping it out and keeping a nice, dry feel on the inside.

Fleece had been largely eliminated from lightweight gear lists in favor of high-loft garments (see below) but it’s seen a comeback when hikers realised that its qualities are perfect for active wear.

Fleece is relatively bulky and heavy so it’s important that this piece wears fit (it needs to layer over the base alone) and it is not thick, not only to avoid bulk and weight but to provide just the right amount of insulation for an active situation.

Think of a fleece “shirt”, not a full-on jacket. Typical weight is below 200 gr. (7 oz)

Haglofs Solo top

Stationary insulation

A high-loft jacket or pullover. High-loft garments are those where the insulation does not hold a structure: that’s actually why they can loft-up. It needs to be sandwiched in between fabric layers. It can be crashed down to nothing and it lofts back up. High-loft garments have a high insulation/weight ratio and pack down small.

Inner and outer shell will be rather windproof. Breathability and moisture management will be similar to those of a wind shell, i.e. at the upper end of limited. This is fine for being stationary.

This garment can be thrown on top of whatever outer we are wearing unless it’s raining.

Typical weight is below 300 gr. (10 oz)

Backpackinglight Cocoon UL 60 hoody with Primaloft insulation

Shell

I’m in between two flavors here, jacket or pullover. A jacket is more functional as you can open/close the zip to let heat out or keep it in, extending the use case of the garment and avoiding put-on/take-off operations when conditions are in-between pleasure and pain. A pullover is simply lighter. Any densely woven, light denier nylon with no waterproofing will do.

The colour choice is tricky here: dark appears as possible best because the shell will be used when it’s rather cold and the dark colour will help with warming up but there is at least one instance when the shell may be needed in warm weather: as bug protection.

Biting bugs will usually bite through base layers. Midgets cannot but mosquitos certainly can. None of them will be able to bite through the shell though. In its use as a bug shirt, a light colour is better: bugs are out only when it’s warm and calm. The shell usually becomes a sauna anyway but a dark colour will make it worse.

For general use, I favor a dark colour but if bugs are gonna be a long lasting issue it may be better to choose a lighter one.

The shell must be as simple as possible: no pockets, no extras, simple construction. For general three season backpacking use, I prefer a pullover. It saves a few grams.

In a pullover fashion, a shell’s typical weight is below 100 gr. (3 oz)

A Montane Featherlite pullover windshirt worked fine in the far north

Waterproof

Only to be used when it rains. Lightweight is key because it will be in the pack most of the time. A densely woven, light denier nylon with some waterproofing (laminated or impregnated) will do. Given the limited breathability, it is acceptable to go for a strictly non-breathable garment and rely on ventilation alone to avoid part of the condensation. Silnylon or Cuben versions exist. Given the limited use-time, Propore garments are a good option despite their fragility.

Same issue as with the shell: jacket or pullover? The zip (full or short one) will be mostly closed for the rain but given that ventilation is so much welcome in a garment that breathes poorly a full zip may be preferable. Vent as much as you can, while you can! You can keep most of the zip open if rain comes mostly from behind. The full zip is my most common option.

Color is mostly a non-factor because it won’t be sunny while the waterproof layer is on.

Typical weight for a minimalist, waterproof top is around 150 gr. (5 oz)

ZPacks CloudCover jacket. It does not even mean to breathe

Sleeping base

Super-thin, long sleeve shirt. It must cover all skin areas (hence the long sleeves) to perform its role of keeping the sleeping bag free of body oils and junk. It should add as little insulation as possible because it should be wearable in the warmest conditions possible. Lightness is key because it will be in the pack all the time the pack is being carried.

Typical weight: 100 gr. (3+ oz)

Thin silk for sleeping comfort and light weight carry

The key is in the kit

The key factor in any layering system is to look at it not as individual items but as a team that works together. The kit described above may successfully face any situation common in three season conditions from either end of the spectrum and anywhere in between.

The weight of all the items stated above as chosen from the ones available in my own wardrobe is 1020 gr. (34 oz) The base layer will never be packed.

Approximate volume of the set

Common mistakes

In a short trip or when the expected conditions are clearly delimited, the Strict Layering paradigm may be altered (hopefully for some good reason) but on the premises that anything can happen (and it will), Strict Layering really works. Yet I see some consistent betrayals to the layering faith:

Waterproofs as all-around shell

I’m aware how tempting it is: a rain jacket is wind and bug proof and it actually looks a lot like any non-waterproof shell. It seems a too obvious multifunction… but it doesn’t meet a key part of the shell role: good moisture management.

Never mind all the marketing spin, breathability of the waterproofs is very limited, way away from what a non-waterproof shell can do. It is a burden we must cope with when it rains but not when it doesn’t!

A shell is often needed in times with no rain: in cold and/or windy weather, a carefully chosen shell will provide more warmth for the weight than any other piece. It is not an insulator itself but it is an insulation booster: it holds warmth in.

It needs to manage moisture well too. If it doesn’t, moisture will accumulate inside. This is uncomfortable and will somewhat compromise insulation inside. Exactly what happens with rain gear and exactly why rain gear is not to be worn unless it can spare us more water than it retains. If there is no rain, the math is simple: don’t use rain gear as your shell.

Some hikers don’t get the difference between waterproof and non-waterproof shells. They take them as different flavors of the same thing and force themselves to choose only one. A wind shell will stand to some rain but it’ll eventually wet out. A rain shell is a hiking sauna. These hikers will not be optimally dressed and can only hope that the conditions meet their clothing choice.

Some hikers do see the difference but don’t think it’s big enough and that both shells’ roles overlap too much. If they are weight conscious, they tend to carry only one shell. It’ll usually be the waterproof one. Hiking sauna strikes again.

The weight savings of getting rid of the wind shell are minimal, maybe non-existent if the lack of a breathable shell conditions the choice in the waterproof garment towards the less clammy of the bunch. These are not the the lightest among the waterproofs.

A carefully chosen wind shell can easily be found for less than 100 gram (3+ oz). Not only outperforms the waterproofs for its intended role but also allows choosing the lightest rain shell available to the point that both shells together can be lighter than a stand-alone rain shell.

Strict layering is certainly most functional but it can also be lightest.

High-loft garments as Active Insulation

Common wisdom does not sometimes make a difference between active and stationary insulation. This means that only one insulation piece is used. Then it’s usually a high-loft one, which is a much better deal for the weight than fleece, wool or other garments with an structure of their own.

In 3 season conditions, it is usually enough to add a shell over the base layer when it’s windy/cold but sometimes it gets too cold for that. Then we add insulation.

High-loft is no optimal active wear: it manages moisture poorly, leaving a clammy feeling inside and possibly accumulating moisture within the insulation material. It suffers from pack pressure all along the back but particularly under the straps. If the high-loft garment insulative value has been dimensioned for stationary situations, it’ll be too warm to hike in, which leads to more moisture being produced, exacerbating the poor moisture management problem.

This is usually taken for granted as the price to pay for a garment that excels while stationary.

When this happens (a garment that performs well or poorly depending on the use case) it is usually a sign of bad role identification. In this case, the Active Insulation role was not identified: no specific garment was provided and this forced the misuse of some other piece.

Some hikers are aware of this and still refuse to take a specific Active Insulation item, using the stationary one instead. It can be not too bad if the Active Insulation role does not happen too often but the weight savings soon get to the point of diminishing returns.

Active Insulation like fleece is much heavier than equivalent high-loft stuff but covers its role so much better. Additionally, Active Insulation can be layered under Stationary Insulation when maximum warmth is needed so a lighter stationary piece can be taken. The Active Insulation garment almost pays for itself in weight.

Once again, Strict Layering can be optimal not only function but also weight-wise.

Different body areas

As outlined above, different body areas behave differently and may require different clothing strategies. The roles identified are all still valid but the actual, optimal kit may differ. Legs, as an example of the other major body area, are much simpler to cover: they don’t get cold easily, they heat up quick when active, sweat is not that much of an issue… not so many clothing combinations are necessary and I usually take a base layer that’s also a shell. The use of the torso was entirely intentional as an example of the most complex case to illustrate the case for layering.

In Summary

It’s easy to think we save weight by choosing multi-functioning clothing items but this should not be at the expense of team function. It may even not be any lighter at all.

Some hikers avoid an item breakdown as described above for redundancy reasons… my advice is to carefully identify roles first, then choose the clothing pieces based on those. If the roles are well defined and the items fill each role reasonably closely, there’ll be no significant redundancy. It may be fine to join roles in a single clothing piece if the expected conditions are narrowed down from the widest spectrum but this is hardly applicable in the long run: if something can happen, it will. Just give it time.

In any case, you must trust your instruments. Strict Layering puts responsibility on the user to choose the right combination for the conditions and this requires confidence. Trust your own experience above anything else.