Civil Defense Shelter

Civil Defense Shelter – A State Of The Art Assessment – 1987

By Richard A. Fleetwood – July 2009

NOTE TO READERS: The excerpt below is from the FEMA Report RR-7/September 1987 book titled Civil Defense Shelters – A State of the Art Assessment – 1986

I have reproduced the 8th and 9th sections here because they provide an excellent overview of the most recent civil defense shelter thoughts and reasoning of the United States. The entire book is available FREE from FEMA, and you can get the information on how to get your own copy from my FREE BOOKS page at This information is strictly provided as a resource to get you going in the right direction when it comes to shelter options, by knowing the full thoughts of our nations leaders…at least their last thoughts about shelter for the past couple of decades. Understand that this publication was produced during the Reagon Administration, and while this may taint your bias a little, the science behind shelter technology has not grown much at all, so the info here is still valid. Take the time to get your very own copy of this great resource for your own library. The bibliography alone contains hundreds of references to other documents and books written the past few decades on the topic of CIVIL DEFENSE SHELTER.

Thanks for your support, and enjoy this new web resource!

Section 8 – Conclusions

8.1 Summary

This report is a comprehensive review of what is known about shelter from the available literature in the United States. An attempt has been made to concentrate on the information which should be known by a U.S. planner. Shelter against a number of natural and technological hazards is considered but the most important threat and the one about which the most information exists is shelter against nuclear weapons effects.

The most important fact to recognize is that there is a very well developed technology for the protection of the civilians against the effects of nuclear weapons. It is potentially very effective and has been extensively tested against real nuclear weapons in the 1950s and, subsequently, blast tested with very large high-explosive charges and shock simulation techniques. Design techniques are covered in a variety of manuals, all of which will produce shelter with very high confidence of effectiveness. However, the reliability of design is usually attained at the cost of great conservatism and excessive expense. The present state of the art in structural design of blast shelters is comprehensively described in Manual No. 42, DESIGN OF STRUCTURES TO RESIST NUCLEAR WEAPONS EFFECTS ( American Society of Civil Engineers 1985 ).

Significant savings on the cost of blast-resistant structures can be achieved by making use of the most advanced design techniques, such as “yield-line theory,” and making maximum use of improved understanding of soil-structure interactions, such as “earth arching.”

The threat to the American public from nuclear weapons is now believed to be of such magnitude that a full shelter program would have to include 160 million blast shelter spaces and approximately 80 million fallout shelter spaces. Blast protection is believed to be required in the areas surrounding military targets and urban-industrial areas. Fallout protection is believed to be required over the entire country.

Existing structures, particularly large masonry or concrete buildings, can provide significant though varying amounts of fallout protection. An effort by the U.S. government to identify such structures in the 1960s and ’70s, has identified an inventory of 245 million spaces which can provide protection factors of 40 or more against fallout radiation.

Unfortunately, most of these spaces are in what are presently believed to be risk areas, and many of them are in the upper stories of multistory buildings which are vulnerable to blast effects. The basements of concrete buildings provide some protection against blast effects but only at low overpressures. There is not nearly enough of this “best available” space to protect more than a very small fraction of the risk area population. With today’s resources, the only hope of survival of the risk area population in an all-out nuclear attack would be a large-scale evacuation of the target areas in several days preceding the attack.

If several hours’ or days’ warning of an attack are available, highly effective fallout shelter protection can be improvised. This protection can include improvisation of shelter in the corner of a basement by stacking books, furniture, bags and boxes of earth, and other mass on and around a table in a protected corner of the basement.

In the 1970s, a technology of producing highly effective shelter from tools, material, and labor at hand was developed. This technique called “expedient shelter” involved the contruction of covered foxholes or covered trenches. All these shelters provide fallout protection factors in excess of 100. The designs using unshored trenches will survive blast overpressures in the region of 5 to 7 psi. Lightly shored verisons will survive 15 or more psi, and one design has repeatedly survived overpressures in excess of 50 psi. If the information on construction of these shelters could be disseminated to the public and 24 to 48 hours were available for construction, very good protection could be developed for very large numbers of people. For the foreseeable future, it is all they are likely to have.

Far more people would survive a nuclear war if shelter were already in place before the onset of a nuclear crisis. One of the major deterrents ot a program providing shelter for all Americans is its cost which will be the product of the cost per space times the number of spaces needed. In the case of blast shelters, the number of spaces needed is approximately 160 million. Fallout shelter spaces needed are approximately 80 million. Small single-purpose small blast shelters can cost from $500 to $2500 a space or more, with $1000 being representative. Blast shelters built into basements of new construction can be constructed for $250 to $500 per space, with $300 being a good representative number. Fallout shelter built into new masonry constrution may cost only in the range of $50 per space. Slightly altering new construction to make maximum use of features which would have been constructed in any case, such as basements, is called “slanting.” This technique is by far the most economical approach to developing shelter.

Construction with the potential for blast slanting includes basements of masonry buildings with concrete first floors; schools and residences deigned partially or wholly for energy conservation, aesthetics, or tornado protection; and underground mining operations for the production of concrete aggregate or agricultural limestone.

The reader is reminded that shelter is but one link in a whole chain of measures to enable a society to survive and recover from a catastrophe, particularly a nuclear war. The spectacular pyrotechnics of nuclear weapons makes it easy to forget that measures other than shelter are required for the ultimate survival of society. The problems of water supply and food supply for the survivors are only the most immediate of these problems. Equally important in the long run is the reestabilishement of food production and production of the vital necessities such as clothing, shelter, and transportation. These will, in turn, require establishment of some type of economy and government authority.


Table 8.1 very briefly summarizes possible different approaches to production of shelter for the American public, the approximate cost, and major advantages and disadvantages. While the different shelter techniques are presented as options, obviously any real program would have a mixture of shelter techniques, depending on the threat and conditions in the area considered.

For completeness a zero option is included in which nothing is spent for shelter space. Under these circumstances, people would make the best use of available basemenet or other indoor space in a crisis. With no expenditure even for education or marking of shelters, use of the existing space would be relatively inefficient and the casualties in an all-out attack would be very high, probably greater than 100 million. Of more interest to the political component of our society, the nation would be much more subject to nuclear blackmail under these circumstances. The threat, or implied threat of a nuclear attack by the Soviet Union could be very coercive, particularly if the Soviets adopted protective postures for their civilian population (i.e., evacuation of the civilians and sheltering of their critical workers and elites).

OPTION 1 is described as “best available” shelter. It is Option 0 with the addition of shelter marking and some information and education. This option is effectively the present civil defense program. It could add a small percentage to the survivors of an atack on congested urban areas if the attack were not too massive. It can add significantly to survivors of the fallout outside target areas.

OPTION 2 is described as crisis upgrading, although it would certainly include the use of space that required no upgrading. The precrisis investment is listed as $1 to $20 per space and would consist principally of local planning efforts. The U.S. civil defense capability has a large component of this option in it at the present time. When coupled with evacuation, this technique is capable of producing space for the entire population for protection against at least fallout radiation.

The principle advantage of this technique is the low precrisis cost. In a sufficiently tense political situation, planning and instructions for crisis upgrading could be developed and disseminated in a few weeks. The principal disadvantage of this technique is that for the target area populations, it has to work in conjuction with an evacuation and thus would require at least a week’s strategic warning in order to make maximum effective use of the approach. It utilizes existing buildings with modification in some cases which can include the dumping of large amounts of dirt on the first floor for additional shielding. If war did not occur, there would be sizeable cleanup cost associated with the use of the technique.

OPTION 3 is described as expedient shelter. This technique employs the construction of the various expedient shelter designs which are available in handbooks (Kearny, 1979). The cost is given as averaging $10 per space which would be a required investment by the indivdual families in digging tools and commercially available printed handbooks. The cost to the government would be much less. In conjunction with an evacuation, this technique combined with crisis upgrading of existing buildings has the potential for sheltering the entire population with much better fallout protection than can be attained by crisis upgrading alone. Its advantage is that the cost to the government would be small. The information required could be disseminated in days.

Expedient shelters also have the advantage of providing high levels of protection–in one case, comparable to the best civilian blast shelter designs. Fallout protection factors in excess of 200 are relatively easy to achieve.

The disadvantage of expedient shelter is that it does require several days’ strategic warning for the evacuation and construction of the shelter. Expedient shelters, once constructed, would have a finite lifetime in most locations of months to a year or two, although more than adequate for any crisis. The majority of designs include wood structural members which would be greatly weakened by the decay and by boring insects in contact with the soil, except in very dry ares.

OPTION 4 would involve the incorporation of fallout shelter into new construction. The National Fallout Shelter Survey has already located over 245 million shelter spaces in existing constuction where adequate protection from the fallout is currently available. However, most of these shelter locations lie in potential high-risk areas ( in other words, cities). A “new construction” option would supplement this existing shelter with additional spaces in those areas where shelter is needed the most. Such an option has the potential for providing fallout shelter outside of the risk areas for the entire U.S. population.

Every building contains construction materials which provide some inherent shielding against radiation from fallout. In some of these structures, adequate fallout shelter spaces could be provided at little or no additional cost. Buildings with basements appear to fit perfectly into this category. Other structural modifications to new buildings might involve more cost, but 1960s Office of Civil Defense programs have demonstrated that the incremental cost of adding fallout shelter can be small in a large number of cases.

Legislation requiring or providing incentive for fallout shelter in new construction outside risk areas would be controversial. Furthermore, the time to construct sufficient shelter space in those locations where it is needed would be controlled by the general construction trends.

OPTION 5 is to modify concrete aggregate quarrying techniques to produce usable underground space near population centers as is being done near Kansas City and Indianapolis. The cost for space production alone is extimated from $20 to $100 ( in 1985 dollars ), and it is estimated by Krupka ( 1965 ) that up to 100 million spaces could be produced in this manner. Krupka estimated that this could be developed in 2 to 15 years, depending on the government incentives offered the limestone miners. It is esimated by Wright, Chessin, Reeves, and York ( 1983 ) that approximately 35 million spaces could presently be developed in existing mining operations.

The advantage of this approach is cost, which is the lowest for any high-quality permanent protection. The other advantage is the level of protection available–an effectively infinite fallout protection factor and very high blast protection.

The principle disadvantage of this approach is that it is not useful for the entire popluation. Some areas simply do not have the necessary geological features that are adaptable to the economic mining operations that produce usable space. In most cases, to use such space would require some evacuation.

OPTION 6 is the slanted earth-sheltered residences and small commercial buildings. Once a decision has been made to adopt earth-sheltered structures for their energy conservation or aesthetic features, the modificaions of the design to provide fallout protection and modest levels of blast-upgradeable capabilities involves very little additional expense. It has been estimated by Chester, Shapira, Cristy, Schweitzer, Carnes, and Torri-Safdie ( 1983 ) that such a shelter could be produced using this approach for $60 or less per space. Earth-sheltered constuction is applicable almost anywhere there is land available to build detached dwellings; it has the potential for sheltering the entire population.

The advantage of this approach is the cost per space and the fact that an aggressive Federal program of incentives, which succeeded in mobilizing the entire housing industry, could produce enough space in two years for the entire population. The Federal incentive payment to replace frame constuction with earth-sheltered construction would cost approximately $300 per space.

A major drawback to this approach is that it would be necessary for people who participated in this program to accept others in their home during the crisis. Agreements between the homeowners and the government to accept a Federal subsidy in exchange for accepting refugees in a crisis would have to be carefully worded to avoid legal challenge.

OPTION 7 involves dual-use basements in new construction. In this option, the entire basement in new buildings would be hardened to whatever level of weapons effects is expected: approximately 30 to 50 psi in target areas. The incremental cost per space is extimated in various studies from $250 to $750 ( in 1985 dollars ). The technique is applicable to the entire population; although, fully developed downtown areas may not have enough construction for several decades to provide new basement space for their entire population. The major advantages to this approach are cost and construction of the shelter space where shelter is needed. It is also applicable over the entire nation whenever basements are feasible.

The main disadvantage to this approach is that there may be rubble and fire problems for such shelters in central cites. It would also take several years to build enough of this space even assuming that Federal funding was not limited. Costs will be higher in areas with high water tables.

OPTION 8, a Swiss basement shelter in new construction, is a carbon copy of the Swiss program. One of more rooms are constructed of concrete in the basement of new buildings to provide sufficient shelter area for the expected occupants of the building. It is estimated by the Swiss that their program costs between $350 and %500 per space ( Federal Office of Civil Defense, 1983, 1985; Heinzman, 1985 ). This cost, developed after 25 years of constuction experience in Switzerland, does include blast valves and rather elaborate air filtration equipment.

The Swiss shelter system has the great advantage of requiring only minutes, since the shelter is located very close to the people. The largest disadvantage is the cost, which implies a program of $80 billion. Shelters under basements also are put at risk from rubble and fire unless they are very carefully designed with rather elaborate escape tunnels and air intakes. The other disadvantage is that the price of even $500 per space is only possible when it is constructed in the course of new construction. to turn over the U.S. inventory of buildings may take from 30 to 50 years in some areas.

OPTION 9 is a retrofit family blast shelter program. The estimated cost varies from $500 to $2500 per space, depending on the type of shelter and the number of people that would be using it. It would be applicable to that part of the population that live in one- and two-family detached dwellings, approximately 160 million people. Its advantage is that it could be deployed in approximately 2 years.

The system of family shelters, supplemented by some other shelter construction in the multi-family housing areas, has the advantage that it would be very effective with only tactical warning of a nuclear attack. It has the disadvantage that the cost becomes fairly substantial, even at $500 per space characteristic of corrugated metal shelters. A program to house the entire population would cost $120 billion. The more elaborate dual-use family shelters can cost upwards of $2000 per space implying a national program of almost $500 billion. The retrofit family blast shelter generally requires a detached dwelling (a yard to dig in) and is not applicable in most built-up central cities.

Option 10 is the construction of single-purpose shelters holding from 100 to a few thousand people. These can be constructed as concrete pipes, corrugated metal arches, or concrete boxes belowgrade or bermed. A number of studies have estimated the cost of this type of structure for critical workers as $1500 to $2500 per space, although this price should come down in a large program and for larger numbers of shelters. It would be applicable in most places, except densely built-up central cities. Its principal advantage would be a relatively rapid deployment, perhaps 2 to 5 years, since it doesn’t depend on the construction of new buildings. The principal disadvantage is cost; a program relying exclusively on this technique for the entire population would cost more than a Swiss program.

Option 11 is the construction of interconnected tunnel shelters under cities. This has been proposed by a few American investigators and has apparently been carried out to a considerable extent by the Chinese under their major cities. The cost is high, approximately $2000 per space. If the program were poorly managed, it could escalate to several times this amount. The system would be only used in very high density population areas, since its cost per space becomes prohibitive in low population densities.

This program produces the Cadillac of civil defense shelters. Given enough entryways, people can get into this system in a very few minutes. The interconnectedness of the system gives excellent protection against rubble and fire: if one entryway or ventilation air intake is blocked or in a fire, then it can be simply closed off and air drawn through the tunnel from other unblocked ventilation intakes. It also permits movement within the shelter system so that very high-density population can be moved out to lower density areas.

To a first approximation these different shelter options can be broken down into three classes: (1) those in the range of 1 to 20 dollars per space, (2) those in the range of a few hundred dollars per space, and (3) those in the low thousands of dollars per space. Those costing one to a few dollars per space, if acquired over several years, imply an annual expenditure in the vicinity of FEMA’S present total budget. Useful space could then be developed with only a modest increase in FEMA’s budget. Shelter options falling under this category are the dissemination of crisis upgrading information, the dissemination of the expedient shelter information and plans, and the low end of modifying quarrying activities near cities.

Shelter options costing a few hundred dollars per space involve an expenditure for the entire population of a few tens of billions of dollars spread over ten years. Annual expenditures for civil defense approximating 1% of the 1986 Defense budget would be required. This amount is the low end of the expenditure on major strategic systems. Monies in these quantities might become available if the United States decides to deploy a ballistic missile defense and go generally to a defensive strategic posture. Shelter options in this category include earth-sheltered structures, dual-use basements in new construction, and Swiss basement shelters in new construction.

Systems requiring $1000 or more per space imply total expenditures of hundreds of billions of dollars and are unlikely for the whole population under present circumstances. Shelter options in this category include retrofit family shelters, retrofit dedicated blast shelters, and tunnel shelters under cities. Shelters of these types may be built by wealthy individuals or do-it-yourselfers or constructed for small numbers of selected personnel required to remain in very high risk areas in a crisis (critical workers).


While a great deal is known about shelter from nuclear weapons as a result of extensive research conducted over the past 40 years, there is room for additional work. In addition to important gaps in knowledge (e.g., the potential for the production of shelter space by changes in concrete aggregate mining practices around cities), there have also been changes in the threat and the possibility of dramatic changes in the political and economic environment in the country.

The threat is changing from large-yield weapons fired against urban areas to intermediate-range weapons targeted with greatly improved accuracy on more specific industrial concentrations and military targets. The advent of the cruise missile means that an active defense system is apt to cause many nuclear explosions outside of presently recognized risk areas. There is indication that the biological weapon threat may need to be reconsidered. Lastly, the upsurge of terrorism, including that not related to the Soviet Union, holds the potential for large-scale threats against civilian populations involving either nuclear, biological, or chemical weapons.

The political and economic climate may change in such a way that interest in shelter is restored. In particular, if the President’s research program on missile defense (the Strategic Defense Initiative) proves that a defensively oriented strategy is technically feasible, a “bottom layer” of passive defenses for the civilian population is logically unavoidable.


A review should be made of concrete aggregate mining practices in the vicinities of population concentrations. Those mining areas where the geological formations permit conversion from open-pit mining to sub-surface mining should be identified and the cost of the conversion estimated. Monetary and other incentives for the conversion should be explored with the possibility of recommending its incorporation in the FEMA program.

The information data base on caves maintained by the American Speleological Society should be reexamined and the identification of potential shelter areas brought up to date.


Experience in shelter construction should be obtained, including actual construction of slanted shelter space in buildings built with 1980-1990 technology. In particular, some actual earth-sheltered residences or small commercial buildings should be constructed using designs slanted for protection against nuclear weapons. It is expected that the cost to the government in this endeavor would be that of providing architectural services to those who want to build earth-sheltered or slanted earth-sheltered residences and that of documenting the construction and costs.


An ongoing effort to expand and maintain a compendium of family shelter plans which would be available to private citizens on request should be established. The plans should be on 8-1/2 X 11 sheets to permit economical reproduction on widely available commercial copiers and should include documentation of construction experience, cost, and critique by experts where available. Emphasis should be on dual-use construction with peacetime functions such as root cellars, wine cellars, study, music room, etc.


It has been decades since experiments have been done with people actually living in shelters for more than a day or two. Some experience should be obtained with modern habitability equipment, particularly that developed for recreation vehicles and boats, such as improved equipment for sanitation, lighting, electrical power generation, water storage and purification, and bedding. The same is true for the expedient versions of these technologies.

FROM YOUR WEBMASTER/EDITOR: There you have it. A massive amount of new information heretofore NOT available on the web. If time allows, I will do my best to get this entire, multi-hundred page book online, including the huge bibliography that makes up a third of the entire volume. Be sure to contact FEMA to get your very OWN hardcopy version of this book. Enjoy, and remember, as long as there are nuclear weapons in the hands of MANY nations that are friend AND foe, there will ALWAYS be a need for shelters to protect FREE people from being killed by them, should any maniac, tyrant, or terrorist resort to actually using them against us.

With over 36,000 warheads on this planet, and NO real tracking of every single weapon available to the entire world, there WILL be a time when the first one gets used on unwitting civilians. This page, and the rest of this website, makes sure you have the information you need….WHENEVER the need might arise.

Richard A. Fleetwood
Founder – SurvivalRing and Civil Defense Now!

Updated: June 21, 2009 — 12:56 am

The Author

Rich Fleetwood

Rich is the founder of SurvivalRing, now in it's 24th year, author of multimedia CDs and DVDs, loves the outdoors, his family, his geeky skill-set, and lives in rural southern Wyoming, just below the continental divide (long story, that...). Always ready to help others, he shares what he learns on multiple blogs, many social sites, and more. With a background in preparedness and survival skills, training with county, state, and national organizations, and skills in all areas of media and on air experience in live radio and television, Rich is always thinking about the "big picture", when it comes to helping individuals and families prepare for life's little surprises.

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