My best advice to someone wanting to learn how to build an igloo is to find a Jeff. Let him do it. (See"How to Build an Igloo.") Jeff has a knack for stacking blocks at the correct angle, trimming them to fit so that their sides lock in place, stacking each one a little bit higher and angled toward the center until a final keystone piece locks everything in place. While going up, the igloo often looks like a house of cards ready to collapse. And blocks falling on your head is part of the fun.
At some point, Jeff commits himself to staying inside until that last block is in place. Then he cuts and digs his way out. We learned early that there are good structural reasons to first build the dome, then cut holes for exits.
Then we let the dome set up while we patch and caulk everywhere, inside and out. Wet snow (which is typical in the Washington Cascades) packs well and is our favorite because you can gently slam it into place. Soft, powdery snow won't pack well and makes positioning of the snow blocks critical.
The rest of us are not sitting around while Jeff does all the work. I'm busy sawing blocks and handing them in, chinking cracks, and stuffing snow mortar into every crevice. Each block is about the size and shape of a case of beer. The foundation blocks are a Canadian 12-pack of bottles; the blocks that form the walls and roof are a little smaller than a 24-pack of cans from the States.
Once our digging trench is going, we generally get three or four blocks in each pass. We make four or five vertical cuts (perpendicular to the ground), one vertical cut across the back, and one horizontal cut across the bottom. If nothing sticks, the blocks drop a fraction of an inch with a satisfying thump. We slide a snow saw into the vertical back-cut and use it as a wedge to push one of the middle blocks forward. The block slides out a few inches to where it can be lifted by hand.
If it doesn't work right (meaning the cuts aren't clean and parallel), the blocks stick together and refuse to budge. They break into pieces along an ice layer if you try to force them. These ice layers are like reading geological time in soil strata. You can tell that weeks or months earlier there was a warm spell or rain or an ice storm. The compact snow slides on them, just as in an avalanche.
Details mentioned in this article were accurate at the time of publication