The advantages and disadvantages of a belowground shelter
A belowground (underground) shelter provides many advantages over an above-ground structure. A belowground shelter can not only insulate you from the cold, it can reduce the midday heat as much as 16 to 22 degrees C (30 to 40 degrees F). A belowground shelter can also protect against enemy attacks, nuclear radiation, solar radiation, and extreme weather events. They are also soundproof and relatively fireproof. However, building a belowground shelter requires more time and effort than for other types of shelters. Since your physical effort will make you sweat more and hence increase dehydration, you should conserve physical energy and construct your below ground shelter before the heat of the day or during the nighttime hours.
How to construct a belowground shelter in the wild
Follow these steps to build a below-ground shelter.
- Find a low spot or depression, preferably a location between dunes or rocks. If necessary, dig a trench 45 to 60 centimeters (18 to 24 inches) deep, and long and wide enough for you to lie down in comfortably.
- Pile the sand you take from the trench to form a mound around three sides of the ditch. This earth dam provides additional protection and adds beneficial load-bearing properties to the structure.
- On the open end of the trench, dig out more sand so you can get in and out of your shelter easily.
- Cover the trench with your material such as a canopy, tarp. or poncho.
- Secure the material in place using sand, rocks, logs, or other weights. In addition to, or in place of a flexible material-like cover, closely spaced logs can be laid across the top of the structure.
If you have extra material, you can further decrease the midday temperature in the trench by securing the additional material 30 to 45 centimeters (12 to 18 inches) above the first cover. This layering of the material act as additional insulation and will reduce the inside temperature 11 to 22 degrees C (20 to 40 degrees F).
The open desert shelter is of similar construction, except all sides are open to air currents and circulation. For maximum protection, you need a minimum of two layers of material. White is the best color to reflect heat; the innermost layer should be of darker material.
Don’t forget that natural belowground shelters, such as caves or man-made culverts, can also be used in a survival situation and save the time and effort required to build an underground shelter from scratch.