In survival situations, a hillside building site should be prioritized. Avoid free-standing mounds, as these are likely logs or boulders buried in snow. Use a snow prod or a long stick to verify usable space for your igloo. [3] X Research source
Measure the depth of your snow while checking consistency. You’ll want the snow to be at least 2 feet (0. 61 m) deep to make your igloo.
A poorly outlined outer wall will result in your igloo’s design being less stable and sturdy. Never build a dome with a diameter larger than 10 feet (3. 0 m), as it will require you to build a perfect dome. This is a nearly impossible task, even with special tools. [5] X Research source
Cut your trench in a way that places one of its short ends flat against the outer perimeter line of your igloo. The place your trench and outer wall boundaries meet will eventually become your outside door. If working on a slope or building your igloo into a hillside, dig your trench directly toward the slope. A handsaw or machete can be used in place of a snow knife. [7] X Research source [8] X Research source
Your blocks should be 3 feet (0. 91 m) long, 15 inches (38 cm) high, and about 8 inches (20 cm) thick, and should taper slightly as you build upward. Run your snow knife, machete, or handsaw along the edges of your first row of blocks where one block joins the next. This will smooth contours and help fit each block together tightly. When your rectangular trench no longer has snow for blocks, cut another trench the same dimensions as the first. All the snow used in building your dome should come from within the perimeter of the igloo. [10] X Research source
This incline will allow your blocks to be stacked in a vertical spiral, creating a snug fit. [11] X Research source
Each row of your igloo dome should slope gradually inward. Use your snow knife, machete, or saw to create a very gentle inward slope for each row of snow blocks. Using your hand, plug any gaps you find in your dome from the inside with snow. Simply pat snow into the gap until it is filled. [12] X Research source [13] X Research source
To increase stability and prevent ceiling blocks from falling, bevel the edges where ceiling blocks meet the row beneath. To bevel, cut the inside corner of your ceiling block so that it forms a flat base with its neighboring block beneath. [14] X Research source
Since your final hole will be exceptionally small, you will have to turn your final block on its end and feed it through the hole on its side. When your final cap-hole piece is balanced on the outer top part of the dome, cut it down to fit in place snugly with your snow knife/machete. [15] X Research source
Cut small, crescent shaped vents into the top or sides of your igloo to prevent the buildup of CO2. [17] X Research source
Try to preserve this block by pulling it inside the igloo. You can save this block to create an overhang for your entrance.
Cut the rectangular dome-wall block in half. Lean each half of your block inward over your entrance trench so that each one holds the other up in an upside down V shape. This upside V overhang for your entrance should be as close to the mouth of the entrance as possible, to provide the most protection. [19] X Research source
You should be able to assess the stability of your igloo by touch. If the blocks feel solid and sturdy, your igloo should withstand the elements. Even if your igloo is a little on the rickety side, in the event of a cave-in, you’ll be able to dig yourself free from the snow easily.
