Insulation Layers

The author in his favourite, “retro”, red and green check 28 oz, 100% virgin wool pants from Codet. With heavy duty wicking longjohns underneath, these are among the ultimate of winter pants.

These are the multiple layers between your base long underwear layer, and your outer shell.    For pants you may only need one layer, but for your top you may need several layers to mix and match to conditions.  Again, the key to using these and staying cool and dry, is to ensure that they vent heat and moisture.  There will absolutely be no so-called waterproof but breathable membranes involved.   You will quickly overcome the breathability of these membranes and become wet on the inside, then chilled.  And any sort of nylon windbreaker top or bottom is absolutely not involved, as you will be drenched in sweat if you use these.

There is an in-between group of membranes in insulation layers which block wind to varying degrees, and these can work well when its not cold or windy enough for an outer shell.  Some are advertised to block close to 100% of the wind, and these are, in my opinion, a potential hazard for getting too hot and sweaty.  Other membranes are more open and let some of the wind come through to keep you cooler and drier.  They have their uses.   Clothing is bulky and heavy and there’s only so much room and weight tolerance in a pack or sled for different layers, so you want maximum versatility.   Everyone has different preferences, but I prefer no wind blocking membranes at all, and opt for maximum breathability with non-membrane polyester fleece and wool.   However if you have success with a wind blocking insulation layer, please let us know how the clothing performed.


For bottoms, its hard to beat the incredible functioning of heavy wool pants.   They do it all.  Wool pants are seen by the modern apparel industry as old fashioned, and most of the apparel industry have rejected them in favour of synthetics.  But for anyone who has used them for winter trekking and living in the bush, its hard to understand why one would use anything else.   In the north, wool pants have been THE staple bottom layer for people who travel and live in the bush.   They are so good, you may never need to use an outer shell with them.

Wool pants used with a medium or heavy duty long john underneath against your skin, have a truly amazing range of comfort.  I and my trekking buddies have used them all day in camp, hauling sled, skiing and snowshoeing, without any shell, from about +3 to -40, and been very comfortable.   By “heavy” wool, I mean about 24-28 oz fabric.   This weight will provide superb insulation that is simply unmatched in by anything in the market in its performance, balancing breathability, insulation, and a good degree of wind blocking.   Wool pant material is flexible at all temperatures, totally quiet (I hate squeaking clothing!), and reasonably durable for abrasion.  And most importantly, you can work around a fire with popping sparks and embers, and relax – you just brush the sparks off, no damage, no worries.   Despite all the trips we do, my buddies and I never fail to discuss around the fire and woodstove just how amazing wool pants are.

Codet wool pants, showing frosted moisture on the outside, which indicates that the moisture is effectively being wicked away from the skin via the wicking long underwear underneath. Despite the awesome breathability, these 28 oz pants insulate very well and cut wind quite well. In extreme winds, shell pants would be used overtop.

And more good news:  You can often find excellent wool pants for under $100 a pair.  Check out army surplus stores for some great deals, and when you find some pairs that fit, buy several!   There are some high-end brands that get up to $200-$300, and are excellent quality, but to get into the gear, you can find less expensive.

The higher quality pants are well worth it if you can afford it.  They will be 100% virgin wool, or a high content virgin wool blend.   The best fabrics are tightly woven threads, and the fabric is very strong, so they last longer.  The threads  remain highly springy, capturing warm air and keeping it, while transmitting moisture very well.  The lower quality pants will be a more felted type of wool weave of non-virgin wool and other fibers, and won’t perform as well.  But you know what – you can’t go wrong with a heavy wool pant of any type.  Even the least expensive mixed fiber pants will perform better than any synthetic pant.

Wool pants are not waterproof of course.  For sitting down on snow, use a pad of something to keep your butt dry, or sit on your duffels packed on your toboggan, or a milk crate hauled as your camping seat.  You should size them to fit lose so you can fit your heavy duty long johns underneath, and be able to snowshoe and ski comfortably.  You will also need suspenders to keep them up, as they are heavier, and this will also prevent sagging and binding.  By over sizing them slightly, you can wear the waist lose with the suspenders, and they vent like a bellows as you move, and they are easier to get into in the morning at -40, ‘cause you will be moving very fast to dress!    You won’t look like a model on the cover photo of a high fashion ski magazine, but you will be warm and dry and maybe look more like a Coureur du Bois!

The weak part of wool pants are the knees.   I am thinking of sewing on thin leather suede knee patches.  Wool can take a lot of abuse, but it will abrade and get thinner with time, so you need to be reasonably careful.  Check the label for washing instructions.  Usually all high end wool pants are recommended to be dry cleaned only.   The good news is that you can usually go many trips without washing wool pants.

: Out for a day hike at -20 and some wind. Upper body layers with fleece underneath, and an outer layer Army surplus thick, densely woven shirt-jac. Also custom fitted with an after market hood. Not a fashion statement, but “wool man” is staying warm and dry all day with the superb qualities of densely woven wool.

There are many excellent synthetic soft shell pants on the market designed for the back country skiing market which breathe and insulate well when active, but they will not survive working around fire, or if they accidentally contact a hot woodstove, will melt.   I am not sure they insulate well when you are less active in camp at night and the temperature plummets.  They also don’t do too well with abrasion, e.g. raspberry canes.

There are alternatives to wool pants for living around fire in deep cold.   If you use a traditional winter camping cotton over pant shell, you can use polyester fleece or other synthetic layers underneath.   The cotton shell pants should have a side zipper to vent the steam.   I am thinking of trying out this system one day if I can procure a pair of the cotton over pants.   Cotton?  Doesn’t “cotton kill” in winter?   Not on the outside it doesn’t, but we’ll talk about breathable fire resistant shells in the Outer Layers section.

 Upper Body Insulation:

When it comes to upper body insulation layers, preferences become quite diverse, so no doubt your system will evolve with experience.  But the choices tend to break out into two types of fabrics:  polyester fleece and wool, both without wind blocking membranes, or if so, a very open membrane.  Better to have no membrane at all, and rely instead on throwing on another fully breathable layer if its windy.   Fleece will instantly melt with fire sparks or if contacting a hot wood stove.  I use fleece, and so I wear my cotton anorak in camp around any fire, and am careful around the stove.

Just broken camp, and ready to ski-haul the sleds. On the upper body, all campers have an inner thin fleece, like a Polartec 100 weight. Upper body insulation layers from left to right: Mountain Equipment Co-op Cornice Jacket made of Polartec 300; Misty Mountain fleece jacket (weight unknown); Army surplus heavy wool.

I will start with a discussion of my current system of polyester fleece layers.    I use one thin layer fleece over my long underwear, and one or two heavier fleeces over this.  To date, including living out at -30 to -40, I have never needed more than 3 fleece layers under my anorak, and usually just one or two.   When you use fire as part of your travel style in camp, you are almost always quite warm gathering, sawing, and splitting wood, and then living around the fire or stove.   Wood heats us many times.  When traveling by day, by far the biggest problem is staying cool and dry, not warm.

All fleece is not equal, and I recommend buying the better technical fabric garments.   The thread and weave structure moves moisture very well and insulates better.  The lower end fleece are matted fibers, and they tend to be less breathable and move moisture more slowly.  However use what you have and get out there!

Hauling sled at -35! (and no wind) Upper body insulation layers only 2, because you must stay dry at these deep cold temperature and vent all moisture and excess heat. You cannot allow yourself to get wet with sweat, so you keep moving, generating lots of heat with little insulation. Its easy to generate all the heat you need when hauling sled! Note all the frost on the outside. This illustrates the incredible ability of modern high quality fleece without any wind blocking membranes, to transport moisture out, using your internal heat pump. Inner layer a MEC 100 Polartec fleece, and outer MEC Cornice Jacket, 300 weight Polartec fleece.

When fleece first became big, they tended to be made with high stand up collars, which I like.   When my neck is cold, I am cold, so I like the option of being able to snug the neck up with a high zipped collar, and even tuck my chin into the collar, with a neck skin protecting beard guard, and to be able to zip it open to fully vent steam.   However in the last few years, many manufacturers have been making fleece with smaller and smaller, and thinner collars that one cannot get a  chin into.  Also the shorter collars provide no protection for outer wool garments which chafe my neck, or camera straps which dig into my neck, etc.     I have no explanation for this short collar trend.  I look for the higher collar fleece.

A rest during heavy sled hauling with skis. Temperature about -10, no wind. Note the upper body insulation layers without any shell for full venting ability.

Unfortunately with the explosion of the urban “outdoor gear” fashion look, many manufacturers have forgotten the technical needs of some of their users, and are producing more mass market fashion-oriented designs which are inferior for the winter camper.   In addition to the loss of high collars, we are seeing the loss of wrist cinches, replaced by floppy open wrists which not only risk getting burned when working with fire, but may dip into your plate of food!   It’s hard to shove an open floppy wrist into an outer layer without it jamming, and that matters in deep cold – you can’t be fumbling with layers and getting cold hands.      We have seen the loss of zipped chest pockets which are good for holding all sorts of essential items like matches, lighters, compass, lib balm, etc.  So its not as easy as it used to be to find the really excellent technical designs.  Hopefully the trends will shift back to less quirky fashion and more technical design.

Hauling sled on a frosty morning about -8. Note the frost on the outer clothing. This is a good sign your clothing system is working. Gotta get that moisture and heat out.

Fleece of all weights will get wet venting moisture when you are working hard.  In winter the moisture vapour condenses very fast when it hits the cold outer zone of your garments.   For example, if you stop from active sled hauling for a rest break or lunch break, you can quickly feel wet and clammy and cold.   Your body heat pump will continue to pump moisture and heat out through hydrophic inner fabrics, but it may take a while.  So its always best to travel on the edge of cold and layer up if need be for a rest, or take more short rest breaks instead of longer fewer breaks.  My crew does not normally stop for lunch when hauling sleds during the day, but instead we snack frequently.  More on that discussion in the Food section.

As good as fleece is, I think the best insulation layers are densely woven wool in fabrics similar to the wool pants.  However these are very difficult to find, and for some of us, we can’t tolerate wool collars against the skin on the neck.   A buddy of mine was able to find army surplus “shirts” which were more like light jackets.  He swears by them for his outer layers of insulation.   And he makes do without an anorak for most of the time, since he can also sit in a rain of sparks by the fire without worry in his wool.  And this high density wool also does very well in the wind, better than an open fleece, and breaths better than a wind blocking fleece.  When the moisture levels are high, such as during sled hauling, resting fleece wearers can get a chill, but wool wearers report that there is more buffer to sudden chills, since wool has these almost magic properties.

Wool “shirt-jac’s” are readily available but often they have a very open weave which is fine for insulation covered by a shell, or in low wind, but quite chilly if used alone in wind.  Many are also lined with nylon, and so you should rip this out if you want to go with one of these.   For the ultimate upper insulation layer, I am still looking for a 28 oz dense weave wool jacket, loosely fitting, with a tall stand up zip collar lined with fleece on the neck and wrists, and a hood.  Maybe entirely lined with a thin polyester fleece.  Please let us know if you find one!

Working hard sawing firewood at -20, on a hot tent trip. Keeping cool and dry before re-entering the hot tent. Upper body single layer of MEC Polartec “sweater” fleece.