Tables II.1 and II.2 will help you decide what type of shelter is appropriate for your circumstances. Table II.1 applies to the construction of shelters in new houses. Table II.2 applies to retrofit situations, in which a shelter is being added to an existing house.
The in-ground shelters referred to in this booklet are built below ground inside a house and therefore can be entered directly from within the house. Other types of in-ground shelters are available that are designed to be installed outside a house. Entering one of these exterior in-ground shelters would require leaving the house. This booklet does not contain any designs or other information about exterior in-ground shelters.