Little things can bug you.
Crowding 3 or 4 people into a winter wall-tent makes it hard enough to sleep, but if someone is thrashing around looking for a missing sock, or a headlamp, or some other little thing that has got away, scrabbling around in the dark, it tends to keep you awake. What’s worse is if your grand-sheet is a common plastic tarp (usually blue).
A poly tarp is a wondrous modern invention of course. You can’t get a more cost-efficient barrier. But as a ground-sheet it’s noisy! It rustles and crinkles and pops! It’s also cold. And very, very blue. But the main thing wrong with it for this purpose is that it’s slippery. Once you’ve been in the tent for a night the packed-down snow of the sleeping area gets a bit crusty and quite smooth. A blue tarp slides around on it like a greased hockey puck on a wet rink.
My brother and I would get our bedding all set up, crawl in, try to get cozy, arrange the pillows (usually a sweater stuffed with other clothes), and then find that the ground-sheet had shifted, and one of us now had our thermarest half on the tarp, and half on the snow. Much muttering and thrashing and attempts to coordinate movement.
So I looked around for a better solution. Canvas tarp? Nope, too heavy to pull around on the sled. It also tends to freeze into the snow. And smells strongly of preservative — which may be a better odour than my brother and I after Day 3, but still isn’t desirable. What I came to use was Typar house-wrap. It was an immediate improvement.
Typar breathes, yet is not wet. It’s cheap, per square foot, although it’s often sold in large rolls which are expensive. It has a slight insulation value. It doesn’t slide around. And it feels better underneath you. It packs-up small. It doesn’t hold moisture. And it’s easy to find.
During daytime in the tent we sit on foam pads on the Typar. At night we lay a thermarest on the foam. Next morning the bottom of the foam pad may be damp, but it’s never wet.
Typar is also fire-resistant. Sometimes in a hot-tent you need a radiation-barrier around the wood-stove to stop the snow melting away. Typar is perfect for this. It won’t melt unless it touches the hot metal, and doesn’t want to burn at all. Yet the snow stays solid behind it. And again it is very light, and packs away to nothing.
Cost: if you can find a builder who will cut you a piece off a 9 ft wide roll, great. That’s the cheapest way to buy it. Otherwise it’s sold in large rolls. A 3 ft by 100 ft roll retails around here for $50. Obviously that’s not wide enough, so use the red Tuck-Tape to join the widths you need. It is very strong stuff, and is useful for many purposes. As for the rest of the Typar, sell it to your friends!