The shelter ceiling, however, should not be higher than the outside ground level of the basement corner where the shelter is located.
The higher your basement is above ground level, the thicker you should make the walls and roof of this shelter, since your regular basement walls will provide only limited shielding against outside radiation.
Natural ventilation is provided by the shelter entrance, and by the air vents shown in the shelter wall.
This shelter can be used as a storage room or for other useful purposes in non-emergency periods.
A PREPLANNED BASEMENT SHELTER. If your home has a basement but you do not wish to set up a permanent-type basement shelter, the next best thing would be to arrange to assemble a "preplanned" home shelter. This simply means gathering together, in advance, the shielding material you would need to make your basement (or one part of it) resistant to fallout radiation. This material could be stored in or around your home, ready for use whenever you decided to set up your basement shelter.
Here are two kinds of preplanned basement shelters. If you want to set up one of these, be sure to get the free plan for it first by writing to Civil Defense, Army Publications Center, 2800 Eastern Blvd. (Middle River), Baltimore, Md. 21220. Mention the full name of the plan you want.
Preplanned Snack Bar Shelter Plan D
This is a snack bar built of bricks or concrete blocks, set in mortar, in the "best" corner of your basement (the corner that is most below ground level). It can be converted quickly into a fallout shelter by lowering a strong, hinged "false ceiling" so that it rests on the snack bar.
When the false ceiling is lowered into place in a time of emergency, the hollow sections of it can be filled with bricks or concrete blocks. These can be stored conveniently nearby, or can be used as room dividers or recreation room furniture (see bench in sketch).