Family Shelters for the Protection Against Radioactive Fallout provides guidance to engineers, architects,
contractors, and the general public in planning family shelters for protection against the effects of radioactive fallout.
It is actually entitles Technical Bulletin TD 5-3 of May 1958.
In any locality in the United States, fallout could require occupants to remain sheltered for two weeks or more. In many areas, radiation levels may permit leaving shelter, for intermittent periods or permanently, after 2 or 3 days. However, since the intensity of fallout at any specific place will be impossible to predict prior to an attack, it is advisable to plan for a 2-week occupancy.
The shelter should provide for each occupant at least 12 1/2 square feet of floor area and 80 cubic feet of volume. In general, ceiling heights should not be less than 6 1/2 feet. The width of the entranceway should be kept to art absolute minimum, usually not more than 2 feet.
I have on this site several different FEMA plans for building expedient and non-expedient fallout shelters inside of your own home.
Some states even have grants to homeowners to build shelters (but I would call them tornado shelters instead of fallout shelters)Family Shelters for the Protection agaist Radioactive Fallout (1958)