<Li> The largest igloos were normally built in groups of two . One of the buildings was a temporary structure built for special occasions, the other built nearby for living . These might have had up to five rooms and housed up to 20 people . A large igloo might have been constructed from several smaller igloos attached by their tunnels, giving common access to the outside . These were used to hold community feasts and traditional dances . </Li> <P> Snow igloos are not spherical, but are built in a shape more closely resembling a paraboloid . Using this shape, the stresses of snow as it ages and compresses are less likely to cause it to buckle because in an inverted paraboloid or catenoid the pressures are nearer to being exclusively compressive . </P> <P> If the walls are of uniform thickness and density, the maximum compressive stress at the base of a paraboloid is S α = γ d 2 24 h ⋅ 1 + cos ⁡ α + cos 2 ⁡ α (1 + cos ⁡ α) cos 2 ⁡ α (\ displaystyle \ mathrm (S) \ alpha = (\ frac (\ gamma \ mathrm (d) ^ (2)) (24h)) \ cdot (\ frac (1 + \ cos \ alpha + \ cos ^ (2) \ alpha) ((1 + \ cos \ alpha) \ cos ^ (2) \ alpha))) </P> <P> where d is the diameter at the base, h is the height, γ (\ displaystyle \ mathrm (\ gamma) \) is the unit weight of the snow, and α = arctan (4h / d). </P>

Where do you find dwelling made of ice who makes them and what are they called