The snow used to build an igloo must have sufficient structural strength to be cut and stacked in the appropriate manner. The best snow to use for this purpose is snow which has been blown by wind, which can serve to compact and interlock the ice crystals. The hole left in the snow where the blocks are cut from is usually used as the lower half of the shelter. Sometimes, a short tunnel is constructed at the entrance to reduce wind and heat loss when the door is opened. Due to snow's excellent insulative properties, inhabited igloos are surprisingly comfortable inside.
Central Eskimos, especially those around the Davis Strait, line the living area with skin, which can increase the temperature within from around 2°C to 10-20°C.
Architecturally the igloo is unique in that it is a dome that can be raised out of independent blocks leaning on each other and polished to fit without an existing supporting structure.
Because "igloo", or iglu'\' in standard orthography, simply means "house" in Inuktitut, since the twentieth century, a snowhouse in Inuktitut is frequently called an igluvigaq, or igluvigait'' in plural, in distinction.