How to build a survival snow cave

By Matt Allred

Published: March 19, 2010

What do you know about snow? Yes, we know it is cold, frozen moisture, but is it also a source of warmth, protection and insulation from the cold? It can be!

Snow caves, both a childhood passtime and a life-saving shelter, are a matter of forethought and training. But before we take on the responsibility of teaching you, the reader, about building a snow cave, let's learn about a familiar experience.

Snow caves usually are not headline news, but several years ago, such a structure was credited with helping save the life of legendary race-car driver and three-time Indianapolis 500 winner Bobby Unser, a resident of Albuquerque, New Mexico.

Unser and friend Robert Gayton found themselves stranded and lost in a blizzard December 1996. Their snowmobiles broke down in Colorado's Cumbres Pass wilderness near Chama. Unser knew he had to get out of the elements in order to survive the night. Temperatures dropped to about 10 degrees, and winds whipped up to 70 mph.

The stranded snowmobilers bored into a snow bank deep enough to get themselves out of the bitter cold and blowing snow. There, within the cave they spent a few dismal hours warming and gathering the strength to push on through waist-deep snow. They walked 12 hours before spotting a barn that contained a telephone. A call was made to some rescuers.

Now, if the two had not made a snow cave, a bad situation could have turned tragic. Though the cave was nothing more than a crudely bored hole, it was big enough to hold two desperate men out of the elements.

It doesn't have to be fancy to work. Snow is an efficient insulator. When properly built, a snow cave can provide some warmth within a relatively dry environment. More so, a snow cave keeps its occupants out of the elements. Here are some "how to" pointers on building a life-saving snow cave.

Avoid building a cave in a wind-blown pocket near a tree- the depression in the snow formed at the tree's base. These pockets generally contain powdery snow that has little bonding characteristics. However, if this is what is available, then something is better than nothing.

The best advice is to look for a location that is out of the wind, preferably up against a mountain slope, on flat terrain surrounded by trees (away from wind pockets) where there is an abundance of compacted snow. Be wise, building in an avalanche path or runoff chute is clear evidence of unclear thinking.

It must be said that remaining calm and thinking through other hazards go hand-in-hand with building the snow cave.

Two types of caves can be built. One requires materials other than snow, the second, nothing but snow. First, a snow cave built in conjunction with snow and other materials- nature-made and man-made.

Thatched roof style
Using a snow shovel (or any device other than your hands), dig a trench a minimum 3 feet deep, 3 feet wide at the top and flared to 4-feet wide at the bottom, and about 6 to 7 feet long.

Lay thick pine bough branches on the floor. This keeps your body off of the snow.

In pitched roof fashion, cover the trench with tree branches by leaning the branches into each other, interlocking the smaller branch ends and boughs. Be sure to stick the branch root into the snow.

At one end of the trench, lean more branches into the pitched roof, closing off the end. Your best source will be numerous tree branches with gobs of foliage, for this and the roof.

Cover the roof with snow. Some snow will trickle down onto the floor, but with some shaking, the snow which dropped on the floor branches will settle through and down. As snow moves, it creates friction, and will set up on the roof. Use judgment not to overload the roof- the branches will flatten as the snow weighs them down. This is also one reason why the trench requires a minimum 3-foot depth.

For the opening, place a space blanket, rain poncho, snowmobile hood or anything that is fairly wind-proof in front. Make your opening so easy exit or entry can be achieved.

The all-snow igloo
A second type of snow cave resembles an igloo. Again, when snow is rapidly and vigorously moved, it creates friction. This friction causes the snow to melt, ever so slightly, and once settled, the snow compacts hard.

With the proper tools or makeshift tools, shovel the snow into a mound- build it long enough that a body can lay prone and tall enough that one can kneel. Pack the snow as you dig. Once the mound is constructed, dig down at an angle, under the mound, a three-foot long entrance hole. Make it only wide enough to slither in. The sloped entrance keeps wind and cold from pouring in and heat from escaping.

Once the entrance hole is bored out, begin excavating the snow under the mound's roof. The hardened snow, will hold its weight with ease. Leave about a foot of snow above your head. Think of this as an igloo - round outside, rounded out on the inside. Place the excavated snow in front of the entrance as a wall or wind break.

Punch a breathing hole through the cave's ceiling. Cover the entry with tree branches or space blanket, if available.

For light and warmth, flame-up a survival candle. Again, make sure a breathing hole is available to exhaust the smoke and body-generated CO2. In either cave, inside temperatures will remain between 33 and 35 degrees- at a minimum- and a body can survive in this climate for a long time.

Outside the cave, build a signal fire and anchor down easily identifiable material on a tree or rock, such as a fluorescent orange vest, jacket, blanket or signal flag.

More simple advice,

Always keep a snow shovel and a ice/snow/wood saw in your snowmobile. Canadian company, Survival On Snow 780/973-5412, manufactures a light-weight snow shovel with an integrated saw inside the handle. Buy it, pack it, use it. These two tools can be your best on-site construction partners.

Don't dig with your hands unless you have no choice. Almost any tool - a ski, helmet face shield, even a pair of goggles - will be more efficient. Avoid exerting yourself to exhaustion - stay calm and conserve your energy. Additionally, working up a heavy sweat will cause more harm.

Don't wait until you are in an emergency situation to build your first snow cave. If you're preparing a deep-woods winter adventure, this practice may save your life.

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