In polar areas, simple shelters will be those already waiting for you in the form of natural caves and hollows. If you carry some kind of bivouac (a temporary camp without tents or cover) in your equipment, then you can set this up and increase its protective abilities by piling up loose snow over and around it, just as long as it can support the weight.
However, to build in hard snow – and trust me, snow will be hard at very low temperatures – you will need some kind of instrument to cut into the snow, much less make blocks from it. In this environment, spades and ice saws are essential pieces of equipment.
Snow or rock caves will be easily recognizable. But, what is not so easily recognizable are the spaces beneath the spreading branches of conifer trees when the snow has already built up around them. A medium-sized tree may have a space around the trunk. A large one may have pockets in the snow beneath a branch. Try digging under any tree with spreading branches on the lee (protected) side.
Snow Trench
This is a much quicker type of shelter to construct than any that are above ground. But it is suitable for only one person and for only a short time – while you are moving or in the process of building a better shelter.
Mark out an area the size of a sleeping bag, including space to support your head, and cut out blocks the whole width of the trench. Dig down to a depth of at least 2 ft (60 cm). Along the top of the sides of the trench cut out a ledge about 6 in (15 cm) wide and the same deep.
Rest the snow bricks on each side of the ledge and lean them in against each other to form a roof. Put equipment below your sleeping bag so that you are not in direct contact with the snow underneath you.
Snow Cave
To form a snow cave, dig into a drift of firm snow to make a shelter of comfortable size. Remember to make use of the fact that hot air rises and cold air settles. Create Three (3) levels: build a fire on the highest, sleep on the center one and keep off the lower level that will trap the cold air. Make a hole through the roof to let out smoke and make another to ensure you have enough ventilation.
Use a block of snow as a door and keep it loose fitting and on the INSIDE so it won’t freeze and jam your entrance way. If it does happen to freeze, a block on the inside will be much easier to free.
Snow House (Igloo)
An igloo takes time to build but centuries of use by the Eskimo people indicate its effectiveness. Build the main shelter first, then dig out an entrance way or create an entry tunnel that is big enough to crawl along. Make sure the entrance does not point into the wind. You could build a bend into the tunnel or create a wind break to make this unlikely.
To construct an igloo using the “circular method”, mark out a circle on the ground about 13 ft (4 m) in diameter and stamp it down to compress the floor as you continue with the rest of the construction.
Cut and lay a circle of blocks along the perimeter. Be prepared to dig a tunnel or leave a space for an entrance. Place another layer on top of them but, as when laying bricks, center new blocks over the previous vertical joint.
Build up more layers but place each other only halfway over the lower tier so that the igloo tapers in or becomes dome shaped. Shape out the entrance arch as you proceed. Seal the top with a flat block. Make ventilation holes near the top and near the bottom – not on the side where the wind is blowing or so low that snow will rapidly build up and block it. Fill any other gaps with snow. Smooth off all of the inside to remove any drip-points. This will allow any condensation to run down the wall instead of dripping on your head.
Parachute Snow House
This is a useful structure if stranded on sea ice where enough snow for an igloo needed to accommodate a larger party is difficult to find. Look for snow or convenient blocks of ice in the pushed-up pressure ridges of the ice.
Mark out a circle, as with a regular igloo, and build up a circular wall of snow blocks and 3 ft (1 m) high. Leave an entrance space if on ice as you will not be able to dig an entrance tunnel. Dig a lower area in the floor for cold air to settle into.
Raise a central column of blocks in the center about 3 – 5 ft (1 – 1.5 m) higher than the wall. Drape the parachute over this and the wall, securing it with a further row of blocks on top of the wall. Anchor parachute cords with further blocks of ice or snow or cut a hole i the ice and pass the rope through it to anchor it firmly.