BUILDING AN IGLOO Pt. 1
by Norbert E. Yankielun
The igloo, also spelled "iglu," and sometimes called an aputiak, is a temporary winter shelter built by native Eskimos primarily for use in winter hunting camps. In their native language, Eskimos call themselves Inuit, meaning "the people." They inhabit much of the Arctic from as far west as the Aleutian Islands of Alaska to as far east as the western coastline of Greenland.
The igloo structure most likely evolved through trial and error over hundreds of years, and without the aid of mathematics or structural engineering theory. Historically, they have been constructed — using a long, sharp blade knife to cut snow block — primarily by Canadian and Greenland Inuit living in Canada in the area between the Mackenzie River delta and Labrador.
Structural Perspective
The igloo is the highest art of snow shelter construction, requiring the precise shaping and placing of snow blocks to form a stable and strong dome-shaped structure. Two structural forces are present in an igloo: compression and tension. Compression occurs when weight is applied that squeezes the snow crystals closer together. Tension occurs when the applied force pulls the snow crystals apart.
The bonded ice crystal structure of sintered snow holds up well under compression; it can bear substantial weight without crumbling. Under tension, however, the same block of snow would easily be torn apart with very little force. For this reason, a cross-section of an igloo more resembles a parabolic arch than a hemisphere.
Source : Architecture Week