Shelter Savvy, part 3

SHELTER SAVVY

Part III: The Shielding Showdown

by Hal Walter

After 12 years, three shelters and much trial and error, in 1969 we were finally ready to build our ideal shelter. After analyzing the terrain and soil composition we decided, with our contractor’s blessing, to integrate the shelter into the basement of our new home rather than dig back into a slope to build a separate structure sharing a wall with the basement. The latter choice, though not as expensive, involved hidden costs; it would have meant building an entirely separate foundation and not being able to utilize two corner walls in our basement. Also, the common wall between the basement and an external shelter would have required a thickness of at least 24 inches, or the shelter move out an additional 24 inches, to provide a dirt barrier between the two 8" walls.

Our main expense from incorporating the shelter with the home was a poured-and-rodded, 24" concrete roof, poured in three 8-inch layers. (Those who build a separate shelter can use either a 4- or 6-inch poured-and-rodded ceiling with a 36-inch earth pack on top to achieve the same Protection Factor.) If pre-stressed concrete beams are available in your area, consider using them for the ceiling, with extra thickness poured on top if necessary.

Integrating the shelter into the basement required that the two inside walls be 24 inches thick. We built two 8-inch block walls parallel to each other and filled all spaces in and between the blocks with concrete. As current cement prices are concrete are high, several extra inches of compacted sand may be substituted between the parallel walls to give a PF roughly equivalent to concrete. We poured a 4-inch concrete floor over the 6-mil vinyl atop the layer of compacted sand.

Our shelter now occupies approximately 365 square feet in a basement area of about 1680 square feet. For maximum security, all the outside basement walls are of poured concrete, with a double-opening steel-plated door 60 inches in width leading into the basement, and any windows eliminated from the side walls.

In order to reduce the possibility of vandalism during our extended absences from the home (six months each year), we originally did not provide an inside stairway from the first floor of the house into the basement. Later we decided this was a mistake, after several winter of wading through 5-foot snow drifts. Fortunately, we had provided extra space under the first-to-second floor stairwell, so we were able to add a basement stairway. For security, the bottom of this stairway was hidden in a closet, and the top fitted with a trap-door device.

At first we planned to use the main entrance and hallway of the shelter for decontamination and clothing storage, but decided against it because the entrance was not far enough from the main shelter to prevent contamination. Instead, we made the basement area outside the shelter into a decontamination area, as it contains a sink, a garden spray on the end of a hose, a washing machine that can be generator-operated and wash tubs with scrub boards for back-up, plus additional space. This area is also ideal for any post-nuclear attack periods when the radiation level has fallen enough to permit semi-protected activity - an option not available with an isolated shelter. Providing such secondary areas makes sense, assuming a scenario of repeated attacks on the United States over a 6-month period. When radiation levels are high, the outside basement area with its 8-inch poured walls would offer a degree of shielding permitting short forays to obtain supplies or equipment. Anyone venturing out of the main shelter during these conditions should wear a pocket dosimeter and have the results monitored and recorded on his exposure card.

It is imperative that your shelter design provide adequate baffling to prevent entrance of gamma rays. Few expedient-shelter designs have any baffling whatsoever, and most others are totally inadequate. Many books now on the market assume that, as long as a shelter is located in a basement corner, there is no need to baffle the entrance. This dangerous misconception assumes a "best-case" scenario instead of a far safer "worst-case" one. There are other shortcomings of these popular shelter designs:

1. When wooden joists are recommended to form the shelters, there is no mention of the fact that wood is a very poor shielding material. (Consider that only 0.7" of steel are required to reduce radiation intensity by one-half; for concrete, 2.2" and, for wood, 8.8".) If you put 1 ½" of wood on every 16-inch center, this makes approximately 10-percent of your shielding relatively ineffective. Whenever wood beams are used, there should be at least one layer of solid concrete block to provide additional shielding.

2. These basement-shelter designs assume no need for an air-filtered system, again resting on a shaky "best case" scenario. What about the possibility of chemical or biological attack? Anyone using such out-of-date shelter designs should provide extra shielding.

Our shelter design provides a 15-foot hallway from the entrance to the main area. We later added another lead-in hallway, perpendicular to the original entrance, that runs back along the 24-inch concrete south wall for 18 feet. We used solid, 37-pound cement blocks (8" x 4" x 16") to provide a shielding thickness of 11 inches throughout this extra hallway, also providing an additional baffle to protect the main entrance. The extra 50 square feet serve as makeshift sleeping quarters for impromptu guests and, in the meantime, for our dogs.

Separations of functions is at the heart of a livable, efficient shelter design. We have provided for privacy as well as communal interaction by using either single or bifold plywood doors at all key points, assuring everyone of darkened, relatively quiet sleeping quarters. Privacy has also been designed into the two toilet facilities. To prevent claustrophobia, the ceiling is of normal height (7 feet 6 inches). A Pullman-car design with hideaway beds, tables and chairs provides flexible eating and sleeping arrangements.

Other articles by Hal Walter

Shelter Savvy, Part 1,

Shelter Savvy, Part 2,

Shelter Savvy, Part 3,

Shelter Savvy, Part 4,

Shelter Savvy, Part 5,

Preparedness Evaluation,

SURVIVAL DEFENSE SAVVY I

SURVIVAL DEFENSE SAVVY II

SURVIVAL DEFENSE SAVVY III