Good idea. My house is almost a natural storm cellar. It is earth bermed on the north with a 12" thick 6' tall concrete wall running the length of the house. There are also a couple of interior 6" thick concrete walls perpendicular to stabilize the 12" thick wall. If you know where to hunker down you'll have concrete on 2 sides of you..Think ahead to your future. My brother had one of those underground metal ones installed and completely stocked it. Now that he has got older, he can't get in and out of it.