Snow Shelters: How to Build a Quinzhee, Snow Trench & Snow Cave

How does a snow shelter keep you warm?

Fresh snow is mostly air — often 80–90 % by volume — and still air is an excellent insulator. A snow wall 30–60 cm thick blocks wind completely and slows heat loss so much that your body heat, and the ground below the snowpack, keep the inside close to freezing. That sounds cold, but it is a world away from −20 °C with a 30 km/h wind outside, which can feel like −30 °C or colder: check it with the wind chill calculator.

Two design rules make the difference. First, warm air rises and cold air sinks, so the sleeping platform must be higher than the entrance; the entrance then acts as a cold sink that drains the coldest air away. Second, the interior must be small, a dome only large enough to sit up and lie down in, so your body can warm it.

These are typical ranges, not guarantees: they depend on wall thickness, the number of people, ventilation and how well the entrance is blocked. Inside temperatures above 0 °C are actually a warning sign — the ceiling starts to drip and weaken. You still need a winter sleep system: two insulating pads (a combined R-value of 5 or more), a winter sleeping bag rated for the conditions and dry clothes. Size your bag with the sleeping bag calculator and read our sleeping gear guide.

When NOT to build a snow shelter

A snow shelter takes hours of heavy digging. Done in the wrong place or state, it can kill you through avalanche, collapse, carbon monoxide or hypothermia from sweat-soaked clothing. Before you dig, run through these questions honestly.

Also avoid building directly under snow-loaded trees, which can drop heavy "snow bombs", over frozen streams or lakes, and alone without anyone knowing your plan. And if you already carry a four-season tent, it is usually the faster, lower-risk option — the snow shelter is a skill for extreme cold, strong wind, emergencies and practice.

Types of snow shelter compared

Which snow shelter you build depends mostly on how much snow there is, what kind, and how much time and energy you have.

Snow trench

The fastest snow shelter. Dig a trench as long as your body plus 30 cm, 60–90 cm wide and about 1 m deep in firm snow. Cover it with a tarp weighted with snow, skis and poles laid across with a tarp on top, or snow blocks leaned together into an A-shape. Keep the entrance at one end, lower than your sleeping level if you can. A trench is cooler than a quinzhee but can be built even by a tired person, and it is a good emergency option. A tarp is ideal as the roof.

Tree-well shelter

Around the trunks of large conifers, branches shed snow and leave a hollow "tree well". You can enlarge it, line the floor with dead boughs and roof it with a tarp or branches. It is fast, but be careful: snow can fall from the branches, and deep tree wells are a known hazard for skiers and snowboarders, who can fall in head first. Only use shallow, stable wells and never enter a deep one alone.

Snow cave

Dug horizontally into a deep, stable drift — often on the lee side of a ridge or bank — a snow cave is the warmest snow shelter. Dig a low entrance tunnel, then turn upwards and hollow a dome with the sleeping platform above the entrance level. It demands deep, consolidated snow and safe, non-avalanche terrain, and the digging is wet work: wear waterproof outer layers and remove insulation while you dig.

How to build a quinzhee step by step

The quinzhee (also spelled quinzee) is the most practical snow shelter where snow is not deep enough for a cave. You pile loose snow into a mound, let it settle and bond (sinter), and hollow it out. Mixing snow layers of different temperatures while piling speeds up the bonding.

Ventilation and carbon monoxide: the rules that save lives

Snow walls are nearly airtight once their inner surface glazes over with ice. Every breath you exhale adds carbon dioxide and moisture, and any flame — candle, stove, lantern — adds carbon monoxide (CO), an odourless, colourless gas that can kill. Deaths in snow shelters and tents from CO are well documented by mountain rescue and health authorities.

A candle can help you judge air quality — if it burns weakly, improve ventilation — but it also produces CO itself, so never rely on it and never leave one burning while you sleep. Melting snow for drinking water is best done outside; our guide to water from snow and ice explains how to do it efficiently, and the boiling point calculator helps you plan fuel.

Collapse safety and the structure of a good snow shelter

A well-built dome of settled snow is strong, but thin spots, wet snow and a flat ceiling can fail. Build to an even wall thickness of 30–45 cm using the thickness sticks, keep the roof arched, never build with slushy snow, and never sleep in a shelter that sags. If temperatures rise above freezing or rain starts, get out.

What a sound snow shelter looks like

• Smooth, round ceiling without flat spots or bulges — meltwater runs down the walls instead of dripping.
• Even glow: in daylight the walls let through a soft, even blue light. A brighter patch means a thin spot; pack snow on from outside.
• Stick ends just visible all round the inside, none missing and none buried deep.
• Dry floor at the platform, with the lowest point at the entrance.

Wet clothing is the other hidden danger. Digging is hot, heavy work; if you sweat into your insulation, it will freeze later. Dig in waterproof shell layers with minimal insulation underneath, take turns, and change into dry layers before you settle in for the night. See our clothing guide for winter layering, and treat shivering, clumsiness or confusion as early hypothermia: warm up, eat, drink something warm and get help if symptoms continue.

Practise first, plan your time and know the rules

Practice drill: on your first snowy weekend, build a snow trench for one in under 90 minutes next to your car or cabin and lie in it for an hour with a thermometer at your chest. Compare the reading with the outside air. Only then plan a quinzhee night — with a partner, a shovel inside and the car as your backup.

Build your first snow shelter near a car, cabin or home, with a partner, in daylight. In winter the days are short: a quinzhee needs 3–4 hours including settling time, so check sunset with the daylight calculator and start early. Carry the basics — a proper metal snow shovel, a head torch, a winter sleep system and warm food — and tell someone your plan.

Snow shelters are also subject to local rules. National parks and nature reserves may prohibit overnight stays or restrict access to protect wildlife in winter; in Germany the rules for overnight stays depend on the federal state and protected-area regulations — see wild camping in Germany. In the Alps, check the avalanche bulletin before every trip. For more winter craft, see our bushcraft basics guide, and for choosing a spot, how to choose a camp site.