Everything you’ve ever wanted to know about igloos but were afraid to ask

The crew was out last week to film some of Gjoa Haven’s residents build one of the most famous images the North: the igloo. If you’ve ever wondered how to build an igloo, and why it works so well to keep you warm in -40˚ weather, here’s a little how to:

1. Find or clear a flat space to build, preferably on well-packed, dryish snow.

2. Start making your blocks: they should be sturdy, well-packed, and while most should be large there should be a handful of smaller ones for the upper layers. Most people suggest using a four-sided wooden mold—like a box without a top or bottom—or a container like a recycling bin. Make sure you’re working with packing snow; if it’s too dry you can mix in a bit of water to make it stick better, but don’t overdo it! In Gjoa Haven, it looks like they have the distinct advantage of being able to cut blocks straight out of the snow, and their expertise is evident in the perfectly cut building blocks you see beside Sammy in the photo here.

3. Draw out the circle that you’ll build on, and start laying down the largest blocks. They should be tightly packed together to minimize cracks, but don’t stress over the smaller imperfections: they are unavoidable and will be fixed later on. It’s also important that the top of your bricks angle slightly inwards, otherwise you’ll never get that dome shape.

4. When the first layer is set, stack another layer of blocks on top, making sure to stagger them so the breaks between bricks don’t match up and compromise the strength of the structure. This works best with someone inside the igloo, as seen here (and remember: this is a pro’s igloo, so don’t be upset if yours is a little more haggard; it’ll still work!)

5. Stack layers almost to the top. Don’t make your igloo too tall or it’ll be weak against the wind, and you won’t be able to finish the final step: put the cap on your masterpiece. When your dome converges enough to put in a single, closing block, you’re ready to complete the frame. Make a block slightly larger than your hole, and have someone outside the igloo place it gently on top, while the person inside steadies. Then, you can shave the edges so that it fits in snugly.

6. From the inside, start filling all the cracks by packing them tightly with loose snow. There are two strategies to avoid getting dripped on as the snow melts slightly over the life of the igloo: some say a completely smooth inner surface will not drip, while others suggest carving vertical grooves down the inside to capture water.

7. Now, you can dig down and create the entrance, which should be below ground level. If possible, the entrance should also tilt upwards into the igloo so rising warm air stays inside while falling cold air can escape. If you expect wind, you can also make an L-shaped entrance.  And if you’re an expert, here’s what your final product might look like:

Why do igloos work? Snow is an excellent insulator, and it blocks the bitter wind which anyone in a cold climate knows is the worst part of winter. A well-constructed igloo won’t result in a balmy home, but when it’s -40˚ outside, the inside of an igloo can hover around 0˚. With the help of a sleeping bag and an oil lamp—make sure to poke a hole in the roof to let the fumes out!—you can be quite comfortable. And the best part about an igloo is it gets better over time: as body heat warms its inside, the igloo melts ever so slightly. When you leave during the day, it’ll refreeze, making it sturdier and improving the insulation. Igloos can also be far more intricate than the cultural perception of them. If you’ve got the time and the skills—not to mention the energy—you can build extra rooms onto your original igloo, and then dig through your wall to connect the rooms or, if you’re feeling fancy, make a hallway. Some igloos can be extraordinary ceremonial structures with many smaller, connected igloos. Our crew, however, has to save their energy for filming. They headed back to camp before construction was completed, looking pretty suave if we can say so ourselves!