Cold Weather Survival
III. IMPROVISED SHELTERS
3-13. Requirement for Improvised Shelters
a. There are many occasions when tents or other regular shelters are not
available. In summer, if the weather is mild, individuals may need protection
only from insects. In winter, however, individuals cannot stay in the open for
long periods unless they are moving. The requirements for improvised shelters
may arise for several reasons, e.g., vehicles carrying tents may be unable to
reach the troops due to difficult terrain or enemy action. In case of emergency,
each individual must know how to protect himself from the effects of the weather.
If suitable natural shelters such as caves or rock shelves are available, they
should be used. If natural shelters are not available, a temporary improvised
shelter must be established.
c. The type of improvised shelter to be
built depends on the equipment and materials available By the proper use of materials
available, some sort of shelter can be built during any season of the year. In
open terrain a shelter can be built using ponchos, canvas, snowblocks, or other
materials. Snow caves, snow trenches, or snow holes may be constructed in the
winter if the snow is both deep and well-compacted. In the woods, a lean-to is
preferable to other types of shelter. In northern areas, nature provides
the individual with the means to prepare a shelter. His comfort, however, greatly
depends on his initiative and skill at improvising.
d. A shelter should
always provide adequate protection from the elements, retain heat, have suitable
ventilation, and provide drying facilities.
A poncho is a part of an individual’s uniform. It is a
multipurpose piece of equipment that may be used as a rain garment, a waterproof
bedcover, a ground sheet, or a shelter. The simplest type of shelter can be made
by merely pulling the poncho over the sleeping bag. For additional comfort, various
types of shelters and lean-tos may be made by attaching ponchos to trees, tree
branches or poles.
a. One-Man Shelter. A one-man shelter (fig. 3-9)
may be made from one poncho. The poncho is spread, hood side up, on the ground,
and the hood opening is tightly closed by adjusting and typing the hood drawstrings.
The poncho is raised at the middle of its short dimension to form a ridge, and
then staked out at the corners and sides. Side stakes should not be driven through
the grommets at the corners or sides, because this may tear the poncho. A short
piece of rope is tied to the grommets and, in turn, to the stakes. Snow, sod,
or boughs are used to seal two sides and one end of the shelter to provide additional
protection from the wind and to retain heat inside the shelter.
Shelter. To construct a two-man shelter (fig. 3-9), ponchos are spread on
the ground, hood side up, with the long sides together so that the snap fastener
studs of one poncho may be fastened to the snap fastener sockets of the other
poncho. Hood openings must be tightly closed by adjusting and tying the hood drawstrings.
Ponchos are raised where they are joined to form a ridge; ropes are then attached
to grommets at the ends of the ridge and run over forked sticks. The shelter tent
is then staked out at the corners and sides, as described in a above. A third
poncho may be snapped into the other ponchos to form a ground cloth.
a. Materials. The lean-to shelter, used in forested areas,
is constructed of trees and tree limbs. String or wire helps in the building,
but is not necessary. A poncho, a piece of canvas, tarpaulin, or a parachute,
in addition to the boughs, may be used for covering.
Size. The lean-to is made to accommodate a variable number of individuals.
It may be built for one man only, teams, gun crews, patrols, or similar small
groups. From a practical point of view, a rifle squad is the largest element to
be sheltered in one double lean-to.
c. Types. Depending on the number
of individuals to be sheltered, two types of lean-tos, single and double, are
(1) Single lean-to (fig. 3-10). To
save time and energy, two trees of appropriate distance apart, and sturdy enough
to support the crosspiece approximately 1.50 meters (5') off the ground, are selected
when operating in forested areas. It may be necessary to cut two forked poles
of desired height, or construct two A-frames to hold the crosspieces, or use a
combination of these supports when bivouacking in sparse wooded or semi-open
A large log is then placed to the rear of the lean-to for added height. Other
methods that may be used are packing the snow down or using snowblocks instead
of a heavy log. Stringers approximately 3 meters (10') long and 5 to 8 centimeters
(2" to 3") in diameter are then placed, approximately 46 cm (18")
apart, from the crosspiece over the top of the log in the rear of the shelter.
Material such as cardboard, canvas or ponchos may be placed over the framework
to preclude falling or melting snow, warmed by the fire, from dropping through.
One or both sides of the lean-to and the roof are then thatched.
lean-to (fig. 3-11). Two single lean-tos are built facing each other and approximately
1.50 to 2 meters (5' to 6') apart. The space between single lean-tos must be sufficient
to permit the occupants to move freely around the log fire placed along the centerline
of this space and to allow the smoke to get out through the opening instead of
gathering under the roofing. If desired, one end of the middle space may be covered
by a wall made of boughs or other materials for additional protection from the
draft and wind.
Heating. In heating a lean-to, any kind of oven fire may be used. The best
type for large size lean-tos, however, is the log fire, so the heat will be evenly
distributed over the entire length of the lean-to, see paragraph 3-21 d. In employing
open fires for heating, precautions must be taken to prevent the fire from burning
too hot and burning down the shelter or setting the roof on the with sparks.
a. Tree-Pit Shelter. In wooded areas, the deep snow
and tree-pit shelter (fig. 3-12) furnishes temporary protection. To construct
a tree-pit shelter a large tree is selected with thick lower branches and surrounded
with deep snow. The snow is shaken from the lower branches and the natural pit
around the trunk of the tree. The walls and floor are then lined
with branches and the roof thickened. Canvas or other material on hand may be
used for the roof.
Fallen Tree Shelter. An emergency shelter for one man can be constructed by
cutting down a coniferous tree at a point about one meter (3') from the ground.
The underside is trimmed and the cut material placed on the ground to provide
insulation. This shelter will provide some protection from the elements for a
man in his sleeping bag. Another way to build this shelter is to tie a pole to
a tree and drape a poncho or similar material over the pole.
A conventional wigwam or tepee can be built in wooded areas by
typing a number of poles near the top and spreading them at the bottom to form
a large circle. This framework is then covered with available tree boughs, canvas,
cardboard, or other suitable material.
In open terrain with snow and ice, a snow wall (fig.
3-13) may be constructed for protection from strong winds. Blocks of compact snow
or ice are used to form a windbreak.
A snow hole (fig. 3-14) provides shelter quickly. It is constructed
by burrowing into a snowdrift or by digging a trench in the snow and making a
roof of ponchos and ice or snowblocks supported by skis, ski poles or snowshoes.
A sled provides excellent insulation for the sleeping bag. Boughs, if available,
can be used for covering the roof and for the bed.
a. Location. A snow cave (figs. 3-15 and 3-16) can be
used as an improvised shelter in the open areas where deep and compacted snow
is available. Normally, a suitable site is located on the lee side of a steep
ridge or riverbank where drifted snow accumulates in unusual depths.
Basic Construction Principles. Basic principles for construction of all snow
caves are as follows:
(1) The tunnel entrance must give access to the
lowest level of the chamber, which is the bottom of the pit where cooking is done
and equipment is stored.
(2) The snow cave must be high enough to provide
comfortable sitting space.
(3) The sleeping areas must be on a higher
level than the highest point of the tunnel entrance so that the rising warm air
will permit the men to sleep more comfortably.
(4) The roof must be
arched both for strength and so that drops of water forming on the inside will
not fall on the floor, but will follow along the curved sides, glazing over the
walls when frozen.
(5) The roof must be at least 30 cm (1') thick.
Size. The size of the snow cave depends upon the number of men expected to
occupy it. A large cave is usually warmer and more practical to construct and
maintain than several small caves. In good snow conditions a 16- to 20-man cave
is the most practical. d. Shape. The shape of the snow cave can be
suit conditions. When the main cave is built, short side tunnels are dug to make
one- or two-man sleeping rooms, storage space, latrine and kitchen space.
Construction. The following steps should be observed in construction:
A deep snowdrift at least 243 cm (8') deep is located. Newly fallen, powdery or
loose snow should be avoided.
(2) The depth of a snowdrift may be tested with
a sharpened sapling approximately 365 cm (12') in length, or in the absence of
trees the shorter ski pole or avalanche probe (The availability of an avalanche
probe is discussed in FM 31-72.)
The entrance is chosen carefully so the wind will not blow into the cave or the
entrance become blocked by drifting snow.
(4) A small tunnel is burrowed directly
into the side of the drift for one meter (3'). A chamber is excavated from this
(5) Excavation is done to the right and left so that the length of
the chamber is at right angles to the tunnel entrance.
(6) Due to the fact
that the individuals digging will become wet, they should wear the minimum amount
of clothing possible to insure that they have a change of dry clothing upon completion
of the task.
f. Heating and Safety Measures. The cave can be heated
with the one-burner gasoline stove or with candles. The fires should be extinguished
when individuals are sleeping, thus reducing the danger of fire and asphyxiation.
If the weather is severe and it becomes necessary to keep a fire going while the
individuals are asleep, an alert fire guard must be posted in each cave. The ventilation
holes must be inspected every 2 or 3 hours to insure that they
have not become
clogged by snow or by icing.
g. Insulation. To insure that the cave
is warm, the entrance should be blocked with a rucksack, piece of canvas, or snowblock
when not in use. All available material, such as ponchos, cardboard, brush, boughs,
etc., should be used for ground insulation.
h. Other Precautions. Walking
on the roof may cause it to collapse. At least two ventilators, one in the door
and one in the roof, are used. A ski pole can be stuck through the roof ventilator
to clear it from the inside. Extra care must be exercised to keep air in the cave
fresh when heating or cooking. The entrance should be marked by placing a pair
of skis or other equipment upright on each side of the entry way.
a. Matches and Fire Starters. A supply of matches in
a waterproof container, heat tablets, or fire starters must be carried by all
individuals operating in cold weather. They are a necessity, especially where
snow and ice add to the problems of securing tinder for starting a fire. In emergencies,
matches should be used sparingly and lighted candles used to start fires whenever
possible, or if available, a little engine oil will help ignite wet or frozen
wood without the flash hazard of the more volatile petroleum fuels. As a safety
precaution, it should be remembered that fire starters are extremely inflammable
and must be kept away from open flames and heat.
b. Selecting Site.
Individuals building a fire in the field should carefully select a site where
the fire is protected from the wind. Standing timber or brush makes a good windbreak
in wooded areas, but in open country some form of protection must be provided.
A row of snowblocks, the shelter of a ridge, or a scooped-out side of a snowdrift
will serve as a windbreak on barren terrain.
c. Starting and Maintaining
Fire. Before using matches, a supply of tinder must be on hand. The use of
heat tablets is recommended for the safe starting of fires. In inclosed areas,
gasoline or other high inflammable fire starters will not be used. In the open,
and under very strict control, small quantities of gasoline may be used to start
fires when other means are not available. Many types of fuel are available for
fires. The driest wood is found in dead, standing trees. Fallen timber may often
be wet and less suitable. In living trees, branches above snow level are the driest.
Green and frozen trees are generally not suitable because they will not burn freely.
Splitting green willows or birches into small pieces provides a fairly good method
of starting and maintaining a fire, if no deadwood is available. Also, dry grass,
birchbark, and splits of spruce bark with pitch tar are excellent fire starters.
It is good practice to secure a sufficient amount of firewood to last throughout
the night, before retiring.
d. Types of Fire. Any kind of open fire
may be used with most of the improvised shelters. In deep snow, a fire base (fig.
3-17) of green wood should be built first to protect the campfire from sinking
into the snow. For a single lean-to or snow wall, afire reflector (fig. 3-10)
may be built of green logs or poles to reflect the heat into the shelter and to
serve as a steadily. The most suitable types for single and double lean-tos are
the log fires (fig. 3-18).
(1) Two, preferably three, logs are used for this
type of campfire. Dry, hardwood logs, if possible, 20 to 40 cm (approx 1') in
diameter and approximately
the same length as the lean-to are selected and
brought to the fire site. First, two logs are place side by side on small green
blocks to support them above the snow or ground for a better draft. Then the third
log is placed in the middle and on the top of the other two logs. For better burning,
the surfaces of logs which face each other are chipped. Before lighting the fire,
small wedges are placed between the chipped surfaces of the logs for better draft.
then started at several places to help it spread the entire length
of the logs. A log fire of this type will burn all night with only minimum care.
When only two logs are used, four vertical stakes must be driven into the snow
to keep one log on top of the other. A disadvantage of this type of log fire is
the fact that the vertical stakes tend to give way when the snow starts melting
around the fire.
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