Snow Trench Shelter

Snow is an Excellent Insulator

Knowing how to make a snow trench shelter or other type of winter survival shelter can save your life in a winter survival situation. The great insulative qualities of snow can be used to help keep you warm enough to survive in even the coldest weather; but only if you know how to use the snow to your advantage.

In this Survival Topic we will discuss choosing which winter snow shelter to build depending upon the depth of snow available and we will actually build the winter survival shelter known as a snow trench shelter, so that you can see one way it can be made.

We will also cover some the problems and considerations involved in building winter survival shelters as well as put to rest some of the misinformation on the subject you may have heard from suspect sources.

Practice Making Winter Survival Shelters

Many survival websites and survival books provide short blurbs and neat hand made drawings of perfect looking winter survival shelters. Some of these so-called survival experts have never actually done the things they write about but merely rehash what they have read in books and watched on television.

Often the information arm-chair survival experts propagate is misleading, partially untrue, or just plain wrong. This is a tragedy in the making for those who may find themselves relying upon this information in a real survival emergency.

Using a Snowshoe as a Shovel

Using a snowshoe as a shovel while digging out the winter survival trench shelter

Be sure to practice making winter survival shelters before you actually need one in a real wilderness winter survival situation. Making a winter survival shelter is not as neat, tidy, and simple as often portrayed in arm chair survivalist writings. It can be hard work performed in the grip of winters cold and wind. Often you must utilize less than ideal materials and tools.

Without practice you may find all that survival book learning is useless when the survival shelter you are attempting to build fails you. Only with hands-on real world experience you will learn how to most efficiently construct your shelter using the materials you have with you or find in the natural environment.

I cannot emphasize enough the need to practice survival skills before you use them in a real survival emergency. With practice you can create winter survival shelters that will keep you alive in the worst winter weather.

Choosing a Snow Shelter Type to Build

Depending upon snow depth there are several excellent winter survival shelters you can make using snow as a building material. The following points are only generalizations and are meant to give Survival Topics readers a rough idea of how deep snow could be in order to efficiently make some of the more common winter snow shelters:

Depth of snow 0 to 3 feet. When snow is at a depth of a few feet or less, a debris hut initially consisting of materials other than snow can be constructed. Snow is then collected and piled on top and sides for added insulation; the more snow the better. A shelter of this kind is covered in the Survival Topic Winter Survival Shelter De-Constructed.
Depth of Snow 4 to 7 feet. If the snow is about four to seven feet in depth a snow trench makes an excellent winter survival shelter. At this depth there is enough snow to form the walls of a shelter when you dig a trench down through it. By creating a roof support structure you can then add a thick layer of snow on top. This Survival Topic focuses on the snow trench shelter method.
Depth of snow 8 or more feet. If you can find an area with a snow depth of more than about seven or eight feet then there is enough snow to make a snow cave shelter. Simply dig a hole into the snow and mine out a cave inside, leaving a roof above you.
Any depth of snow. Forget about making an igloo using blocks of snow. This method of making a winter survival shelter out of snow is typically expounded in survival books and websites by people who have never attempted it themselves. Building an igloo that keeps you as warm as the winter survival shelters listed above requires a great deal of expertise, experience, and is very time consuming as compared to the other methods. For these reasons igloos are best left to the Eskimos and northern peoples who have been doing this sort of thing for untold generations - and to the arm-chair survival "experts" who write about them. During a winter survival emergency building an igloo is certainly not an option for the inexperienced.

Making the Snow Trench Survival Shelter

Warm Snow

Temperature on the surface: -10F (-23C)
Temperature 3-ft (1-meter) underneath the snow: 30F (-1C)

Snow is an excellent insulator. By digging down just a few feet you can tap into a much warmer environment, warm enough to help you survive the coldest winter weather.

For this Survival Topic I selected an area where the snow depth was about five feet, which is not really deep enough to make a snow cave but is well suited to making a snow trench shelter. Although I could shovel more snow on top to make a large pile and then dig out a cave, the extra work required to do this is not welcome when building winter survival shelters.

Before you start making a snow trench shelter, try to select an area that has adequate materials nearby for use as insulation from the ground. Evergreen boughs are an excellent choice, as are dry materials such as cattail stalks, leaves, or twigs if you can obtain enough of them. You will also need something in which to construct a roof support. Logs and sticks will often work well for this. The closer these materials are to your shelter the less distance you will have to carry them.

As you can see in the first picture, I have selected an area to make a snow trench and am using a snowshoe as a shovel to dig out the snow. In many wilderness winter survival situations you are unlikely to have a shovel. However snowshoes make excellent improvised shovels for digging in snow and you are likely to have them when traveling through deep snow country.

To shovel snow using a snowshoe simply utilize the snowshoe binding as a handle and the front part of the snowshoe as the blade. Dig into the snow using sweeping motions and deposit the snow in a pile next to the trench you are digging. You are going to use the snow you dig from the trench as roof insulation so keep it nearby.

Lacking a shovel or snowshoe you may have to improvise a tool with which to dig snow. Try using sticks or a pot from your mess kit.

A Word of Caution

Making a winter survival shelter is a laborious and time consuming process. Be prepared to spend at least several hours of sustained effort in its construction, especially if you are alone.

Working hard in winter can lead to heavy sweating that wets your clothing. You also need to be careful not to become wet with melted snow. If your clothing becomes soaked with perspiration or melted snow while building the shelter, it will become inefficient; you may not be able to maintain body temperature once you stop working. This could lead to very serious consequences when you are trying to survive in the cold winter environment.

Snow Trench Shelter

Try to build your snow trench shelter as small as possible while allowing room for the addition of insulative materials such as evergreen boughs, grass, or other dry plant material

The smaller the shelter (without your touching the walls) the easier it will be to heat.

Pace yourself and adjust your clothing so that you always stay a little on the cool side to limit the amount of sweat you generate. If you are using the layered clothing system this should be no problem as it gives you the means to mix and match clothing according to the conditions.

Be careful with snow that comes in contact with your clothing and brush off as much as you can before it melts from body heat. As you make a survival shelter using snow this can be very difficult but is important if you want to remain warm when the work is done and you are inside the winter shelter you have made.

You may want to keep a fire going nearby as you make the winter survival shelter. Fire can help keep up your morale as well as dry out your clothing before you become chilled or even hypothermic.

Once you have finished making your winter survival shelter you will want to use the fire to thoroughly dry off your body and clothing before retiring inside. If you can find a few rocks place them on the edge of the fire so that they become hot. These rocks can become useful for heating your shelter and will be discussed below.

Remember the Survival Topics adage when it comes to cold weather survival: Stay Dry, Stay Alive.

Using Snow as Insulation

As I dug out the snow trench shelter the temperature was -10 F ( ) on the surface of the snow. Digging down just 2-1/2 feet through dry fluffy snow I reached snow that was still damp from a thaw the area had over a week ago. As you can see in the picture the snow was wet and sticky enough for me to form a snowball with it, which means the temperature of this snow is near the freezing point of water.

The fact is, just several feet below the surface of the snow the temperature rarely drops below 20F no matter how cold and windy it is on the surface. In this case the difference between -10F on the surface and about +30 degrees beneath the snow is 40F, which will definitely give the wilderness survivor an edge in staying alive no matter how cold the weather is on the surface.

Size of the Snow Trench Shelter

Evergreen Boughs and Roof

With the addition of a thick layer of evergreen boughs and roof support structure made of poles, the winter survival trench shelter is taking shape

One key to building a proper snow trench shelter is to keep its length and width as small as possible while digging downward as far as you reasonably can. You want the trench to be wide enough to accommodate a thick layer of insulative evergreen boughs or other material and just room enough for you to get in comfortably.

A small space inside the winter survival shelter will be easier for you to keep warm using your own body heat and perhaps the heat from a candle or hot rocks brought inside from a fire pit.

As you can see in the picture, I am laying in at the bottom of the snow trench shelter after having dug out the snow to a depth of about five feet. Because the shelter is meant for only one person, the trench is about 4-1/2 feet wide and 5 feet long. A short tunnel on one end to makes room for my lower legs and feet; there is no sense in digging out this part of the shelter completely.

An added bonus is that I was able to dig right down to the ground level. This taps into the latent heat the earth stored during the warmer months and insulated from the cold temperatures by snow above it. The exposed ground can radiate several degrees of extra warmth into the shelter, a welcome addition when the goal is to keep warm enough to survive.

Insulating the Snow Trench

Although the inside of the snow trench is considerably warmer than the outside temperature, you do not want your body to be in direct contact with the cold wet snow of the shelter’s sides or ground. For more information on loosing body heat through conduction read the Survival Topic on How Body Heat is Lost.

Roof cover

The roof of this snow trench shelter is covered with a survival blanket. You can also use a thick pile of evergreen boughs, bark, or other plant materials

When I lay flat on my back with my legs and feet in the tunnel there is a space of about 1-foot all around between my body and the wall. This extra space will be filled with evergreen boughs or any dry fluffy material I can find.

Natural insulation materials are placed inside to help retain your body heat and make a comfortable nest. In this case I am in a white pine forest and am using the boughs of this tree to make a snug nest inside the snow trench. Other excellent materials include hemlock or balsam fir boughs, cattail stocks and cattail down, leaves, grasses, or any other dry fluffy material.

Place the insulating material as thickly as possible, especially on the floor in order to lessen heat loss between the floor and your body through conduction. I recommend at least one-foot of material (measured when it is fully compressed by your body) on the floor and six inches along the walls. If you can obtain more insulation than that place it on the floor since this is where the majority of heat loss from your resting body will occur.

Making the Snow Trench Roof

The snow trench will need a supporting structure for the roof. Cut some poles and shove their ends into the walls of the trench about four feet above the floor as shown in the picture. Then cover the roof supports with a thick layer of material; evergreen boughs, cattail stalks, grasses, leaves, sticks and twigs, or other natural materials work well.

In this case I happened to have a survival blanket which I spread on the roof in order to save on the time and energy required to harvest additional natural roofing materials. If I had plenty of resources it might be better to use natural materials for roofing and save the survival blanket for use inside the shelter.

On top of the roof structure shovel several feet of the snow you dug out from the snow trench. Be sure all the cracks are well sealed. The more snow you place on top of the winter survival shelter the better.

Snow Trench Shelter Door

Cut a door into the side of the shelter for ingress and egress. You will want to make something to plug the hole when you crawl inside the snow trench shelter. I always carry a 50-gallon drum liner, which is little more than a very large garbage bag, in my survival kit. Fill the bag with snow and drag it to plug the opening as you crawl inside. This will seal you and your body heat in while keeping the cold and wind out.

Snow Trench Shelter Door

It is important that your survival snow trench shelter has a good door

Here you can see the entrance to the snow trench has been plugged by a 50-gallon drum liner filled with dry powdery snow. As I crawled into the trench shelter I pulled the shelter door in behind me, sealing in the warmth and sealing out the cold and wind

A garbage bag, pack filled with snow, or even a large snowball can also be used as a door plug to seal heat in and keep the cold and wind out. Poke a small hole in the side of your winter survival shelter in order to admit a little air. Make the hole as close to floor level as possible so that the air that escapes from your shelter is not the warmest air, which naturally rises toward the ceiling.

Heating the Snow Trench Shelter

As mentioned earlier, you designed your snow shelter to be small and snug. This means there is a minimum of air space; your own body heat can raise the inside temperature considerably.

Because the snow trench shelter you made is nearly airtight, you need to be extremely careful of carbon monoxide poisoning if you attempt to heat it using any kind of flame.

Your survival kit should contain a long-burning candle, which can be put to excellent use as a small heater. Because the flame is so small there is usually little worry about carbon monoxide poisoning from a single candle.

Another excellent way to heat your shelter is to heat rocks in an open fire outside and, using wooden tongs, bring them inside the shelter. Place the hot rocks on a stable, non-burnable platform. Often once you have heated the winter survival shelter to a comfortable temperature your own body heat will maintain it for quite some time.

Safely ensconced in your snow trench shelter, you can wait out the worst winter weather no matter how cold and windy it is outside. All outside sounds are muffled so that several feet under the snow may be the quietest place you have ever been. As the cold and storm rages outside, your survival shelter may very well save your life.