If it is closely packed, the walls may be only a few inches thick; if the snow is soft, the blocks are thicker, that they may hold their shape.

The blocks for the bottom layer are sometimes two or three feet long and two feet high; but sometimes they are much smaller, as there is no ironclad rule about it.
When sufficient blocks have been cut to make an igloo, an Eskimo takes his position on the spot (usually a sloping bank of snow) which is to be the center of the structure.

Then the others bring the snow blocks and place them end to end, on edge, to form an egg-shaped ring about the man in the center, who deftly joints and fits them with his snow knife.

The second row is placed on top of the first, but sloping slightly inward; and the following rows are carried up in a gradually ascending spiral, each successive layer leaning inward a little more, and each block held in place by the blocks on either side, until finally an aperture is left in the top to be filled with one block.
This block is then properly shaped by the man inside the igloo; he pushes it up endwise through the aperture, turns it over by reaching through the top, lowers it into place, and chips off with his knife until it fits the hole like the keystone of an arch, firmly keying the structure, whose general proportions are not unlike those of a beehive.
A hole just large enough for a man to crawl through is cut close to the bottom on one side, and any superfluous snow inside the igloo is thrown out through this hole.

In the rear or larger end, the sloping floor is leveled off to form a bed platform, and in front of this the floor is dug down a foot or more for a standing space and a place for the cookers.
Then the sleeping gear and cooking outfit are passed into the igloo, and, after the dogs have been fed and tethered for the night, the members of the party enter, the opening at the bottom is closed by a large block of snow, the edges of which have been shaped and chipped by a saw knife to make a tight joint, and everything is ready for the night.
After the cookers are lighted, the igloo is soon comparatively warm, and in the arctic regions, when men are tired out from a long march, they generally fall asleep easily.