the best cheap and easy shelter i ever saw was done buy a guy who just had a small one story tract type home that sat out on what was a corn field in the Midwest.he did nothing more than cut a hole in a closet floor,beat a hole in the slab and work digging out a hole one five gallon bucket at a time.the pit did not look more than 10x10 and five feet deep.no beds or survival gear but i think he reinforced the overhead with 2x12's.being underground nothing was going to get thrown thru a wall,you see programs on TV that show 2x4's shot thru cement blocks.post storm photos show the homes gone but the floor which is at ground level still intact and sometimes swept clear of everything.a old time farmers root cellar is even better i would think because you would not have what might be left of the home on top of you but to make one you need a farm yard or plenty of room in a yard.in Minneapolis i don't expect a storm like we have see in the South,there has never been one,but for a quick shelter we have a stout storage closet under the basement steps.it would take seconds to toss out clutter and get under the heavy shelf's and pull the bags of tents and sleeping bags around us....another 1AM long winded rant/sermon/speech,sorry.