Utah Shelter Systems - Because Survival Is The Highest Priority

Paul & Sharon's Office


© 1987 - 2014 Utah Shelters Inc. All rights reserved.

Concrete shelters are comfortable and can be designed to accommodate large numbers of people.   The Swiss, almost exclusively, build concrete shelters that are placed in deep underground basements of homes, hospitals, schools, hospitals, public buildings, hotels, and most all other buildings.   The entire population of Switzerland can reach a shelter in a matter of minutes. These concrete shelters are built to last for hundreds of years.  Homes and buildings in Switzerland are built to the same standard; therefore, the shelters do not need to be re-built. On the other hand, the expected life of steel shelters is only100 years.  However, the average life expectancy of homes and buildings in America (because they become outdated) is approximately 70 years.  It, therefore, would not be cost effective for the United States to mandate a national concrete shelter program under our homes and buildings.      

Swiss shelters for private homes must are built to a minimum code of 1 atmosphere (15 psi), and government civil defense shelters are built to a 45-psi code. Military and critical mission personnel in Switzerland are assigned to heavy blast shelters in the 200-psi plus level. Please take note that our ‘All Hazard’ steel shelters, if installed correctly, also protect to the 200-psi level. We believe these Swiss codes should set the standard for shelters in the United States.

Governments that mandate a national shelter program can afford the luxury of building large population concrete shelters.  They build in mass and tax their citizens accordingly.  They build and install these shelters to last for long periods of time.   When people move and purchase another home, they can be assured that the shelter in the new home will be built to the same code as the shelter they have left.

Shelters constructed of reinforced concrete are very effective; but, when built even to the minimum Swiss code, these concrete shelters cost four to five times more than the same size steel shelters.   Steel shelters, by virtue of the small diameter, angled entrances and the deep burial depth, achieve a much higher level of protection than is found in the Swiss public shelter systems.

People in America mistakenly believe that shelter ceilings and wall slabs of an 8-inch thickness will protect them from the effects of radiation and blast.  They have been misinformed.   Eight inches of concrete, with no building overhead, will give a radiation PF of less than 8.  Even in low radiation risk areas, this level of protection is not adequate to save lives.  The accumulated dose for one week would reach between 300 rads and 600 rads, with an expected probable death rate between 50% and 100%. The minimum blast and radiation requirement, with no building overhead, is 22 inches (see chart below). 

Shelters built under a building, however, have an automatic PF of approximately 15, because of the mass of the home and roof above.  An eight-inch slab roof under a building will give a PF of about 100.   People in low to medium fallout risk areas will most probably survive with no symptoms. People in high fallout risk areas, however, will receive about 200 rads, with some deaths.  They will also be expected to have an 11% increase in survivor cancer deaths later in their lives.  This concrete level does not meet the 14-inch minimum blast and radiation requirements for shelter slabs under buildings.

The following are the minimum concrete thickness for Swiss standards of 15 and 45 psi. 

15 psi (minimum requirement)

45 psi

Roof slabs (not under building)

Roof slabs (under building)

Interior shelter walls            

Exterior walls (underground)

Ext. walls (partially exposed)

Exterior walls (exposed)

22 inches

14 inches

14-20 inches

10 inches

20 inches

32 inches

Roof slabs (not under building)

Roof slabs (under building)

Interior shelter wall         

Exterior walls (underground)

Ext. walls (partially exposed)

Exterior walls (exposed)

34 inches

22 inches

20-26 inches

10 inches

28 inches

48 inches

The interior wall thickness is dependent on the window exposure in rooms exterior to the shelter.  The specifics of this information are offered in the manual,  ‘Technical Directives for the Construction of Private Air Raid Shelters’.  See ordering information under the section entitled ‘Pricing & Ordering’.

Rules for Installation of Concrete Shelters:

  • Concrete shelters should be as deep underground as possible, to protect against the effects of radiation and blast.
  • The shelter should have as much of its external surface against the ground as possible; to protect against radiation, fragments, projectiles, conduction of heat generated by the occupants, and protection of heat caused by external fires. 
  • The shelter should be located under the massive parts of the building to protect against radiation, conventional bombs and fire.
  • The shelter should be located as far as possible from potential fuel concentrations and flammable materials.
  • The shelter should be placed so that emergency exits and air inlets can be extended from the building into zones free from debris to better the possibility of unaided exit and intake of fresh air.
  • Doors must be constructed of 8-inch thick concrete, with gas-tight gaskets.  The living area should not be in ‘line of site’ of the door.
  • Doors to the shelter room should be off-set from doors to the air lock. 
  • If there is no airlock, entrance doors to the shelter room should be turned 90 degrees from the entrance hall.  

Doors must be constructed with no less than 8-inch thick concrete, with gas-tight gaskets.  The living area should not be in ‘line of site’ from the door.  

Airlocks & Decontamination Rooms:

Air locks are interim rooms designed to gain safe access from the outside to the main shelter room.   Airlocks should have two gas-tight doors, which are never to be opened at the same time. This assures protection of the shelter room from radiation, blast pressure and war gasses.  People entering the air lock from the outside, must close the outside door and stay in a closed down condition until the air of the air lock has been purged and the air pressure has reached a positive state equal to that in the shelter room. The airlock should be small with a maximum area of 54 square feet, to assure the proper purging of the air. 

The air lock, in small shelters, can also act as the decontamination room, which serves as a cleaning and dressing room for people contaminated by poison gas or radioactive dust.  The decontamination room should be used to store protective clothing, which must be worn at all times by persons leaving the shelter.  In larger shelters, the decontamination room should have a shower and toilet area built into the room.  For shelters housing more than 100 persons, the decontamination room should be a separate room, having access to the airlock.

The airlock and decontamination rooms should be constructed of the same thickness of concrete, and same protection levels as are prescribed for the shelter room.  Filtered air from the shelter room should be exhausted into the air lock (or from the shelter room into the decontamination room, and then to the air lock).  Air from the airlock should be exhausted to the outside or into the basement.  This allows for a continual movement of filtered air throughout the shelter and airlock.  Each room has the same volume of air entering as it does exhausting.       

People often use a concrete airlock to gain access to their steel shelters.  The air lock is placed at the basement level.  The steel shelter is placed 10 feet away from the house, and 8 to 10 feet below the air lock, depending on the diameter of the steel shelter. Entrance is gained to the airlock from a gas-tight concrete door in the basement wall. A steel door on the floor of the air lock leads to a 7 ft. stepladder, accessing a 10-foot long horizontal tunnel leading to the steel shelter at the lower level. The steel shelter should also have an exit to the outside.

Safe Rooms:

Safe rooms should be built to the same standard as air locks.  After completing your risk assessment, if you find that security from home invasion is your main concern, you may wish to build the air lock without the attached shelter room.  You may wish to replace the 8-inch thick concrete door with a safe door.  Either will lock from the inside.  Common safe doors are not a good solution if you are building against earthquake or nuclear blast.   Under these conditions, the door could warp and block your egress.  We prefer to have both an exit and entrance into any room built for the security personnel.    

There are creative ways to hide the door to your ‘safe room’ and/or ‘air lock’.   Please contact us for suggestions.  Hiding this door is as important as securing the door.

Basement Shelters:

It is next to impossible to retrofit a basement shelter into an existing basement and achieve the proper shielding and blast protection needed to meet minimum Swiss standards for 15 psi.  The maximum blast protection achieved is usually well under 5 psi., as the shelter walls and ceiling must be self supporting and independent of the building in order to reach protection from those blast levels.   Significant radiation protection factors, however, can be achieved, by placing enough mass overhead and around the shelter. Some areas of low blast may receive high levels of radiation from rain out, local winds, or fast moving prevailing winds.   To reach a minimum PF of 100, place at least 14 inches of concrete (or 18 inches of dirt) overhead.  The walls receive radiation from windows and door openings.  They must, therefore, be thicker than the ceiling.  There are formulas for figuring the thickness, according to the number of openings, but a good approximation would be 18 inches of concrete (24 inches dirt equivalent).  You may want to frame a 24-inch wide wall with wood and fill the interior of the wall with dry sand.

Be sure to provide adequate ventilation in your shelter.  See the sub-title, ‘Ventilation’ under ‘Shelter Components’ on our web site.   Carbon dioxide builds very quickly and may drive you out of your shelter before it is safe to leave.

You can find a basic plan for a basement shelter under ‘Pricing’.  These plans are meant only to guide you, and are not engineered to a specific size.  Walls, ceilings and floors of homes came in many sizes, thickness and strengths of materials.  It is mandatory that you consult a civil engineer to draw your engineered plans, before beginning the construction of any basement shelter and before cutting into foundation walls.

© 1987 - 2014 Utah Shelters Inc. All rights reserved.