Building an interior room out of mattresses works. People with few resources can also do much the same thing with blankets, comforters and old sleeping bags.

There are lots of ways to assemble such a room but one handy way is to rig what amounts to a couple of clothes lines about six feet high and about six feet apart through the middle of an interior room. Nails will work to hold light rope or wire if you hit a stud but screw eyes into a stud are far less likely to pull out. The additional strength will allow you to safely tension the lines more and make for easier assembly and a better room.

Along these you hang your blankets, or what have you, vertically from the lines and between the lines to create a room. And more blankets across the top to create a roof. Clothes pins, large safety pins, and spring binder clips can be used to hold the pieces together. They can also be stitched with a large upholstery needle and heavy thread or string.

Assembling a tight sleeping area in an interior room can make a huge difference in your ability to survive through cold temperatures if the heat is not working.

As with all such expedient assemblies and strategies you have to be careful. Fire, smothering and carbon monoxide poisoning have to be avoided. Better to be a little cooler than comfortable, than dead.