Building igloos is something that all Arctic explorers had to be proficient at for survival and supply drops along their long research routes. The frequent building of igloos is documented in David Haig-Thomas’ excellent Tracks In the Snow, a narrative that followed Robert Bentham’s trail and gives an idea of how many of these things they were building, often on their own. Robert Bentham wrote a short instructional article on how to do it, which is as true today as it was in the 30s when it was written (it’s about cutting ice, after all). I’m not sure if this was ever published, or exactly why he wrote it, but I’m fairly sure if he’d known about the internet he would’ve wanted random people looking for information on building igloos to learn from his world-worn experience.
The original document is shown in the pictures and transcribed alongside:
Notes on the Building of Igloos
From the point of view of the igloo builder, snow may be divided into two main types, soft unconsolidated snow and snow that has been compacted by wind action. The first type is useless for igloos and it is by no means all snow drifts that can be used in the construction of these, at first sight, chilly dwellings. Drifted snow can usually be found in all stages of hardness, from being so soft that blocks of it crumble when picked up, to so hard that it is impossible to cut it at all. The igloo builder has to find the happy medium, the snow he requires being soft enough to enable him to cut blocks easily but at the same time it must be sufficiently consolidated not to crumble.
The ideal number for building an igloo is two, one to cut the blocks and the other to do the building; the only tools required are a rip saw and a snow knife, which is an ordinary 12” butcher’s knife fitted with a rather longer handle than usual. The first step is to find suitable snow. When a drift of the right hardness is found, the saw is slowly pushed in to ascertain whether or no this consistency is maintained with depth. In some cases drifts are made up of layers of snow, some soft and others hard and with a little experience these layers can be detected by pushing in the saw. When suitable snow has been found the block cutting can commence; the size of the blocks depends on a number of factors such as their strength, the size of the igloo to be built and convenience of handling. The most suitable size under ordinary circumstances is about 30” by 13”x6”, though this is perfectly abritrary and good igloos can be built with both smaller and larger blocks; it is more satisfactory, however, to use oblong blocks rather than square ones as the former stand more securely than the latter. It is most convenient to cut blocks vertically but under certain circumstances, for example when there is an insufficient depth of snow, they have to be cut horizontally.
The first block of an igloo must be sufficiently wide to stand up by itself and also to support the next block. The second block is then placed in position and the edge nearest the first block is bevelled so that the whole of this end is in contact with the first block. The second block is then pushed laterally so that it presses against the first block and at the same time inclines, slightly, inward. The angle of inclination depends on the size of the igloo being built. Thus there are now two blocks, one leaning on the other, but they are not secure, as the second block can be pushed over with the greatest of ease; in other words the junction of the two blocks is insufficiently tight. In order to remedy this, the snow knife is inserted beneath the second block and moved along until it is within about 4” of the other end. This process is repeated until a wedge of snow has been removed from beneath the block and the knife can be moved backwards and forwards without effort. A sharp blow is then delivered to the top of the second block, at the end nearest the junction of the two blocks, which now press tightly together.
This process is repeated with block after block until the first circle is complete, and the last block fixed is close to the first. A wedge is cut off the top of the latter, so that it now has an approximately triangular form. The next block is laid upon this sloping surface and secured in the same manner as has already been described. It is at this stage that the assistant outside becomes so valuable, though he is not, of course, indispensible. If a man is building an igloo by himself, he has to clamber over the wall with which he has surrounded himself, cut a block, clamber back again, place it in position, bevel and secure it. When the wall becomes too high for him to climb over, it is necessary for him to cut a hole in its base so that he can crawl out and fetch the blocks. Quite apart from the fact that one man working alone has to do a lot of unnecessary work in climbing and crawling out of the igloo, he is all the time running the risk of wrecking the work of an hour by making a false step. When he has an assistant, however, the risk is obviated, as the assistant cuts the block and places it in position; all the builder has to do is bevel and secure it.
A good igloo never has two junctions vertically above one another, so it is occasionally necessary to adjust the size of a block to avoid this; otherwise the same process is employed until finally there is only a small hole left at the top and a block the same shape as this hole has to be cut. The last block is in no sense the keystone of the structure; like all the other blocks in the igloo it merely rests against its predecessor and is not an intrinsic part of the building. The builder is now completely encased and all there remains for him to do is to cut a small hole for ventilation purposes and another larger hole from which he can emerge.
The igloo is now finished except for the filling in of the cracks between snow blocks, in order to exclude draughts. This is a job which is usually performed by the assistant as the builder will be too occupied enlarging the inside of the igloo by shovelling out snow. It can be seen that quite a small snow house can be made into spacious dwelling by merely removing the floor, a consideration which is of the utmost importance when a site is being chosen for an igloo. The whole of the snow, however, is not removed from the inside, since it is convenient to leave a snow bench for sleeping purposes; otherwise it would be necessary to leave the sleeping bags etc. on the floor and they would tend to become filled with snow and ultimately become icy.
The habitable life of an igloo is at the most, three nights since the heat inside partially thaws the roof and the moisture thus formed is absorbed by the blocks, which thus become converted into ice and lose their insulating properties. When an igloo is to be used for some considerable time it is necessary to erect a tent inside, as otherwise it would first become icy (and therefore very cold) and ultimately thaw to such an extent that holes appear in the roof.