5.11 Expert Tips: Building A Snow Trench Shelter

Finished Snow Shelter

As part of our ongoing 5.11 Expert Tips series, we’ve tapped into the expertise of our resident expert on snow shelters, Eduardo. Below you’ll find advice and suggestions for surviving an unexpected situation in a winter climate.

If you ask any survival or outdoor aficionado about their preferred winter shelters, most will answer with “an igloo.” Even though they are the most glamorous and the most comfortable, in real life, they are the wrong selection for most situations.

If planned in advance, built with some acquired construction skills and the required time is available, an igloo is a fantastic semi-permanent shelter.

In reality, a snow shelter will be, most of the time, a hasty solution for an unpredicted bivouac in the wild. Spending an unexpected night outdoors in the cold can be the result of a skier getting lost in a blizzard, or having an accident and being unable to progress to lower ground. It can also be a trekker that is lost or trapped in a rapid weather change. Whatever the reason the adventurer or sportsman has to face spending a night in sub-zero temperatures, it is a situation which poses a real risk to his or her life.



The first protective layer you carry is your clothing — your first pseudo-shelter. Wearing the right clothing will protect you from the elements and greatly simplify the construction of a hasty, lifesaving snow trench shelter.

The first question you should ask yourself is: which winter conditions may I be facing? The answer will dictate your equipment needs. Whilst the enemy is always hypothermia, the threats can be remarkably different when crossing a frozen lake, climbing an icy north face or hunting in the high mountains.



Ideally, your MEL (minimum equipment list) should contain the bare essentials you need to carry to survive. I emphasise survive, because here we are not talking about being cosy. If you are carrying a rucksack you will have more options in the selection of your equipment, but if you are a skier or triathlon racer you will have to keep your equipment weight down to maintain mobility. And this balance between mobility and safety is the one that can get you killed as many will say “I can’t carry survival equipment!” You can carry it and you should carry it.

For example, for a high mobility skier that may tend to be out there with no equipment at all, below is what I recommend.


In a skiing environment you likely won’t have trees to cut branches from to make your shelter roof, or to serve as isolating floor. You will not have wood to burn either so do not bring an axe here. Instead, focus on one large space blanket to maintain body heat and a small basha tarp to serve as a roof or bivouac. To add some navigation capacity, bring a cut-down 1:25000 or smaller scale map that covers your area, so you can find your way out the next morning and a mini compass in your watch. A gas lighter that can give you light and heat, and last but not least, a fully-charged mobile phone completes your MEL. These few items will prove essential when the time comes, weigh next-to-nothing and if placed properly in your clothing pockets won’t limit your mobility.

Not included in your MEL is your waterproof clothing that will serve to protect you from the elements, nor the skis and ski poles that will become your shovel — and roof beams once the trench is shoveled.

You can start out in perfect conditions, but survival situations usually happen unexpectedly. Therefore, I would suggest planning a practice day in good weather and dry clothes, so you learn how to build a trench shelter using your MEL equipment and what limitations your equipment may have. After that, you can do some adjustments.




The first decision you have to make is where to place your shelter. You want the entry to face downwind. If on a slope place it perpendicularly to help the hollowing of the trench itself.


The trick is to hollow out just enough snow to get yourself under the surface without feeling claustrophobic. I would never make the trench wider than your own shoulders nor higher than what you need to sit down. Always remember that the larger it becomes, the colder it will be.

My recommendation is to place the entry opposite to where your head will be so you breathe the hottest air possible, so plan the height and entry location accordingly, considering that you can enter crawling and turn around sideways. If you have to make a two-man trench, I like to make it wide enough so you can lay side-by-side, share core body heat, communicate and see each other’s face at night. Being able to talk and see a friendly face can mean the difference between conserving your will to survive, or not.


Mark your shoulder width and your body length in the snow, plus 50cm (20”) extra if you can, for a cold air trap near the entrance. If you have a large knife, a folding saw or ideally a wood saw then you could cut rectangular blocks 25x25x50cm (10”x10”x20” ). Pry them out and place them as the sidewall over the edge of the marked lines. If you do not have a knife or saw, use any hard surface as a shovel and pile the snow you hollow out, making a wall on the side.

Snow Shelter Wall

Try to not use your bare hands as even the best gloves can take a beating by caving with them and you will need your hands dry, to keep them from freezing. Compact the sides and keep raising the sidewalls until you reach the planned height. Any extra snow or blocks you pull out should be placed about 50cm to the sides, so you can move them in with ease after you have placed your basha tarp roof over the sidewalls and use them as securing weights.

Once you have constructed three sidewalls, place anything you have as roof beams – a snowboard, skis or ski poles, and place your basha tarp over the top. Secure the basha sides with paracord cord if you have any, using the horseshoe or bollard technique, and place snow or snow blocks over the sidewalls and let gravity do its part. Place the weight on top of the sidewalls, not over the actual roof.

Make the entrance small enough to get in, which makes it easy to close with the tarp sides or with some extra blocks or snow, making a small ventilation hole, once you are inside. If you have time, cut a 30 to 40cm (10” to 15”) deep square hole right next to it, to trap cold air and keep the floor as warm as possible.

The lack of insulation of the floor will make your night miserable, so place anything you can find to separate your body from the cold snow floor. Don’t plan on sleeping too much but you will at least be alive to see the sunrise!

So, with a little practice, a reasonable snow trench can be cut in only about 30 minutes and it can keep you alive until the weather improves.

Snow Survival Shelter


Categorized in Gear Posted December 12, 2015 , , , , , , , , , , ,