How to Build an Emergency Shelter (Start With the Floor)

Most people building an emergency shelter start with the roof. That is the wrong order. Cold ground pulls heat out of you far faster than cold air does, so what goes underneath you matters more than what goes over you.

Insulate the floor first

Anything dry and thick: leaves, bracken, pine boughs, dry grass, your empty pack, a coiled rope. Aim for more than looks sensible — it compresses under your weight, and compressed insulation stops insulating.

If you do nothing else, do this.

Keep it small

A shelter you can fill with your own body heat beats an impressive one you cannot. Big enough to lie in, high enough to sit up if you can manage it. That is the whole specification.

Three shelters worth knowing

Tarp lean-to. Run a line between two trees at chest height, hang the tarp or poncho over it, weigh the edges with rocks, and angle the low side into the wind. Ten minutes, and it handles rain and wind well.

Debris shelter. No tarp. Lean a ridge pole from a stump or fork to the ground, lay branches along both sides, and pile leaf litter over the whole thing — thick, far thicker than feels necessary. Slow to build, warm when done.

Snow trench or cave. Dig into a firm drift, not loose powder. Keep the sleeping shelf above the entrance so cold air drains out. Punch a vent through the roof and keep it clear.

Where not to put it

• Not in a dry watercourse. Flash floods arrive with no warning under a clear sky.
• Not under a lone tall tree in a storm.
• Not at the very bottom of a valley, where cold air pools at night.
• Not under dead branches.

The snow shelter warning

Ventilate it, always. A sealed snow shelter with a stove or even a candle inside can kill you in your sleep through carbon monoxide. Keep the vent clear through the night, and work slowly while digging — sweating into your layers is the fastest way to lose the night.