The order that keeps an emergency bivy usable is ground layer first, then pad, then the bivy, then the sleeper and the sleeping bag inside it. Most hikers run it backwards — bivy out of the sack first, spread flat like a one-person tent, pad and bag wrestled in afterward — and that reversal is what turns a two-minute job at dusk into a fifteen-minute fumble by headlamp. It also pins the breathable top of the shell flat against the sleeping bag, which removes the air gap the laminate needs in order to move your vapor, and that is the one problem a bivy cannot recover from overnight.
The deadline is light, not dark
I run this as a procedure with a clock on it, and the clock does not start when the sun goes down. It starts the moment I catch myself looking at the light behind the trees instead of the ground in front of my feet. That's the tell. Not the junction that wasn't there, not the pace that fell off an hour ago — the light-checking.
When that happens I usually have thirty or forty minutes of usable light left. That's enough to do the whole setup twice: find flat ground, kick the cones and rocks off it, and lay the system out with gloves on and fingers still working. A headlamp is fine for reading. It's bad at the one thing that actually matters here, which is judging texture — whether the ground is flat, whether it holds water, whether there's a root under the spot your hip is going to land. You cannot see texture by headlamp. You guess at it.
Stopping early costs miles. It costs fewer miles than crawling around on a slope in the dark, and far fewer than the night you spend on ground you couldn't judge.
Three shelters, three procedures
This is where people borrow the wrong procedure. A bivy sack, an emergency bivy, and a bothy bag are not one object with three names.
A bivy sack is a sleeping shelter: a zippered shell you get inside of, usually with a waterproof-breathable top, a heavier waterproof floor, taped seams, and sometimes a single hoop or pole holding the hood off your face. An emergency bivy is the same idea stripped down — often no hoop, sometimes no full-length zipper, just a short opening or a slit, and a very light floor. Less structure means more of the outcome depends on the order you do things in.
A bothy bag is not a sleeping shelter at all. It has no floor. You sit inside it with your pack, your heads and shoulders hold the roof up, and the edges get tucked under thighs or weighted down. It's for stopping: eating, adding a layer, making a decision, waiting out a squall with three other people. You deploy it in one motion — shake it out, everyone in at once, edges down, top vent cracked, one person managing the opening so it doesn't flap the warmth out. Condensation inside a bothy bag builds fast because it's four people breathing into a sealed bag, so the vent stays open and somebody wipes it down before it gets packed. If it has a stove vent panel, that's between you and your own judgment — the same rule as the bivy applies, and the rule is that a flame and an exhaust stream do not belong in the same fabric box as your face.
Pad under, not in
Here's the part that gets reversed most often. The pad goes under the bivy, on top of the ground layer, not inside the shell.
Reason: the pad is the bulkiest, least compressible item in the system. Put it inside and it pushes the top fabric up against the sleeping bag everywhere you're lying. The laminate has nothing to work with — no air gap for vapor to cross — so the shell becomes a plastic bag with a mattress in it, and by morning the bag is wet at the shoulders and the foot. Pad outside, and the bivy goes back to being what it was designed to be: a thin shell over an insulated platform, blocking wind and trapping a layer of still air while the pad does the actual insulation work. A shell with no pad under it is a windbreak, not warmth. Conduction beats convection every time the ground is frozen.
The ground layer underneath is cheap insurance. A sheet of polycro, a pack liner, or the empty pack laid flat: it keeps the bivy's floor off grit and off wet ground, and it keeps the pad from pulling moisture from below. It weighs almost nothing and it's the difference between a floor that survives a season and one that doesn't.
Caveat, and it's a real one: some bivies are built with an internal pad sleeve and a full bathtub floor, and those want the pad inside, in the sleeve, exactly where the sleeve is. Follow the sleeve. What you should not be doing is standing at a junction at blue hour trying to remember which kind you own. Know the order for your rig before you need it.
Lay the whole thing out with an orientation, not just a position. The hood opening points away from the wind and away from the direction the rain is coming from, which means the foot end takes the weather and the opening sits on the sheltered side. Do that while you're on your knees with the pad in your hands, when the rig weighs nothing and you can just rotate it. After you're zipped in, changing orientation means getting out.
Once you're in, four checks. I do them in the same sequence every time, because sequence is what stops you skipping one when you're tired.
The drawcord at the opening gets snugged down to about a hand's width, not closed. That opening is the only vent the shelter has. Seal it and you wake up with the inside of the shell beaded and the foot of the bag damp. Leave it wide and you get rain or spindrift on your face. A hand's width is the compromise, and if you're unsure, err toward open.
The hood has to hold the fabric off your face. Either the hoop does it or you prop it — a fleece, a soft stuff sack, anything that isn't a boot. Fabric resting on your mouth means you're breathing straight into the shell all night.
The zipper slider gets parked where your hand lands when you reach up without looking, and where it isn't under your shoulder. A slider under a shoulder is a leak and a pressure point at the same time.
The foot end comes off the ground. Not off the pad — off the ground. The foot of the bivy shouldn't sit in a dip where water will pool, and it shouldn't touch vegetation or a rock face, because anything the shell touches wicks, and the lowest point of the bag is where the loft dies first. On any kind of slope, foot end downhill, head end uphill, so if water moves it moves away from your face.
What stays outside, and why
Wet boots. The issue isn't dirt, it's water. A wet boot inside the shell dumps liquid into a space that's already handling every bit of vapor your body produces, and the bivy has no way to get rid of it. Boots stay out, laces loosened, upside down, tucked under the edge of the pack or into a bag. If it's going to freeze overnight the tradeoff is real: cold boots in the morning, or a damp bag all night. Take the cold boots.
Food. The bivy is a shelter you are sealed into, which is the worst posture to be in when something comes into camp. You can't see it, you can't move quickly, and you're inside a bag. So food goes wherever your food plan puts it — canister, hang, whatever the trip calls for — and it goes there before you get in, not after. Doing it after means unzipping in the dark, which is when the shell gets wet and everything you were keeping dry stops being dry.
The stove. Outside, always, and run before you get in rather than after. Two reasons, neither negotiable: a bivy is a nearly sealed box of fabric that you're breathing inside of, and the flame plus the exhaust go into the same air you're using. And the shell melts. Being cold is not new information to the stove.
Your pack goes outside too, but put it on the windward side as a windbreak, and keep it from touching the shell. Contact is the enemy — anything pressed against the fabric cuts loft at that spot and wicks moisture through.
Morning: shake, wipe, wear it dry
Nobody wants this part. It takes four minutes and it decides how the rest of the trip goes.
The bag comes out first and gets stuffed immediately, into its own liner, before anything else is touched. Then the bivy comes off the pad inside out and gets shaken hard, well away from where you slept. If there's frost on the inside, shake it off before it melts. Frost shakes off. Water doesn't. Then wipe the interior with a bandana or a microfiber. Condensation inside a bivy isn't a defect, it's physics — the shell moves vapor more slowly than your body produces it when the outside air is saturated, so a beaded interior at dawn is normal and expected.
Then the decision: dry it or carry it. If it's dry enough, it rides on the outside of the pack — mesh pocket, shock cord, top of the lid — for the first hour of walking. If it's still wet, it rides outside anyway. Never in the main compartment. A damp shell in the main bag wets everything it touches, adds water weight you carry all day, and then you sleep in it that night, which is the one scenario where the order you got right the night before stops mattering.
Four minutes in the morning is the whole difference between a bivy that lasts seasons and one that quietly quits on you in the middle of one.
The sequence is short enough to memorize: decide while you can still see, ground layer, pad, bivy, you and the bag, four checks, everything wet stays out, shake it dry before you carry it. What gets people isn't the gear. It's doing it four steps out of order and finding out at two in the morning, which is the worst possible time to learn anything.
