How to dig the perfect snowcave efficiently

There are lots of online guides out there describing how to build snow caves, why write another one? Well, to be honest, most of them are pretty bad. I've made a fair number of snow caves now - often digging by myself to sleep the family - and I think I've gotten pretty good at it. 

Some caveats:

• "It's fun" is really the only good reason to sleep in a snowcave. Don't think of a snowcave as some sort of fast-and-light alternative to a tent. It is so much easier to just carry a tent. Especially if it's your first snowcave plan to spend basically half a day digging it, and probably you should carry a tent anyway as a backup. Also, don't think of a snowcave as some sort of miracle "emergency" shelter - in winter conditions there is no such thing (other than a cabin with a wood stove). In an emergency, if you did not prepared to spend the night, you are almost always better off to press on and hike off the mountain (unless you are lost, in which case you should stay put. Please don't get lost while unprepared to spend the night.)
• Don't build your shelter somewhere you are going to get avalanched, or people might walk onto it and collapse it from above. Not that the cave is likely to actually collapse from somebody walking on it.
• We live in the BC South Coast mountains - we get tons of snow. So this article basically assumes the snowpack is at least 2 meters deep. There are other options (igloos, quinzees) for when the snow isn't as deep.

The Gear

In addition to food all the other winter camping stuff, for snowcaving specifically, you'll want:

• One shovel per digger. Avalanche rescue shovels are great. It's best to have a smallish one for the person inside, since the toughest part is when space is tight. My favourite is the Voile XLM - normally you need to pick 2 of the 3: light, strong, cheap... but the XLM has all three (thanks partially to being small, which is it's own advantage). (Personal beef/aside comment - a lot of people think that shovels with big blades make for more efficient digging... but unless your upper body strength is way above average the limit on how much snow you can move per scoop is going to be the weight of the snow, not the size of your shovel blade - even with something small like the XLM).
• An avalanche probe to check snowpack depth and discover trees etc. before excavation. At least 230 cm.
• A ski pole (or similar) for poking a breathing hole.
• Waterproof-breathable (hardshell) jacket and pants, and warm mitts/boots.

Probably you had all those things with you anyway... other things that are not strictly necessary, but really nice:

• Knee pads, if you've got them, worn under your waterproof pants will help keep your knees and legs warm and dry.
• Big fully-waterproof shell overmitts, to wear over your normal mittens. None of this treated-leather/fabric stuff. Waterproof.

You should plan to do most of your digging in just your base layers and waterproofs. It's hard work, and you don't want to sweat too much, but (especially if you are the person inside) you will be constantly pressed up against the snow and have snow falling on you so you will need waterproofness.

Location

You want to pick a good spot:

• Not somewhere dangerous (avalanche, rockfall, etc.). Obviously.
• Ideally you go near the top of a short 35 (ish) degree slope/roll. Note that 35 degrees is the perfect steepness for avalanche incidents (steep enough to rip, not so steep that it self-regulates well). That's why it should be a small roll (like, the size of your cave). Steeper is OK - your ceiling will be thicker, shallower is going to be a lot more work digging.
• Probe the area first to make sure there is enough snow, and there are no trees awaiting discovery in the middle of your cave.
• Then set up some kind of warning system (maybe ski poles and some rope?) above your location so that people don't ski onto your cave from above. Don't be tempted to steal the BC Parks trail wands. For one they are not yours, also they will probably actually attract people.

Dig!

1. Start out by digging a trench into the slope. You need to get deep enough into the slope for your cave and a trench is way less work than a tunnel since you can actually move around without crawling. Throw the snow downhill, as far as you can. Expect to spend at least at much time moving the snow away from your trench as you do actually digging it - that's why a trench is less work. If you were digging a tunnel you'd need to drag/push that snow while crawling. This can be done by two people with some coordination.
2. As soon as the firm-snow trench depth is just a little deeper than you are tall switch to digging a tunnel. You want it a little wider than you are, and not much taller than you need to crawl through. As soon as possible start tunnelling straight upwards until it's standing height in there. This is the hardest part. Really, you are not making a "tunnel" in the traditional sense but a standing-height vestibule you need to duck to enter. The "wall" behind you to your trench can be pretty thin, maybe as thin as 10 cm or so if the snow is firm. The thinner the wall (and shorter the tunnel) the easier it will be to push snow out later.
3. Standing in your new vestibule start clearing a platform out in front of you. Aim to make the floor just a little bit higher than the top of your doorway, so warm air is trapped inside. Getting the floor above the height of the door makes a huge difference in temperature - with the warm air trapped it will make it right around zero almost regardless of how cold it is outside. If you have a partner you can just tip the snow down into your vestibule and they can fish it out from between your legs. If not you will need to pile it beside you in there, squeeze out beside it when it's full, and then fish it out yourself. I've found that clearing a platform as far as I can reach with my shovel in front and to the sides is big enough for two people to sleep comfortably and still have space around the sides for gear. If you have more than 2 people you will probably need to climb up onto the platform.
4. ​Most guides recommend a tall ceiling with steep sides to prevent drips, but I've found this isn't really important. What is important is to make the ceiling smooth, with nothing sticking out for drips to form on. I also like to put the vent hole right at the tallest spot in the ceiling, and to make that tallest part in the vestibule - then all the warm humid air has a place to go where it's ok to drip or have precipitation fall down. A single hole about the size of your average ski pole grip should be about right to keep it somewhat dry and fresh in there, but still warm.

And, you're done! When you are truly done with your cave you should collapse it, so it's not a hazard to others. Even though the ceiling is strong enough to support your weight now it might melt out before it compresses itself flat due to show creep. Plus this gives you a chance to see just how strong your ceiling was! Usually I have to dig before I can break through. It's enough to leave it as a giant hole - the idea here is simply not to leave a hidden hazard. People need to move around in the mountains with their eyes open anyway. Here's a cheat-sheet: