ABOVEGROUND
HOME
FALLOUT
SHELTER
H-12-2 / November 1983
(Supercedes H-12-2 dated June 1980)
General Information
This family shelter is intended for persons who prefer an aboveground shelter or, for some reason such as a high water table, cannot have a belowground shelter. In general, belowground shelter is superior and more economical than an aboveground shelter.
The shelter is designed to have a protection factor of at least 40, established by the Federal Emergency Management Agency for public fallout shelters. It also provides significant protection from the effects of hurricanes, tornadoes, and earthquakes, and has sufficient space to shelter six adults.
The shelter can be built of two rows of concrete blocks, one 12" and one 8", filled with sand or grout, or of poured reinforced concrete. Windows have been omitted; therefore, electric lights are recommended for day to day use.
The details and construction methods are considered typical. If materials other than shown are selected -- for example, concrete blocks faced with brick -- care should be taken to provide at least the same weight of materials per square foot: 200 lb. per sq. ft. in the walls and 100 lb. per sq. ft. in the roof. The wood frame roof over the reinforced concrete ceiling probably would be blown off by extremely high winds such as caused by a blast wave or tornado. However, the wood frame roof is intended primarily for appearance; the concrete ceiling provides the protection. When using the shelter for protection against high winds, DO NOT place the concrete blocks in the doorway or windows.
This structure has been designed for areas where frost does not penetrate the ground more than 20 inches. If 20 inches is not a sufficient depth for footings, one or two additional courses of concrete blocks may be used to lower the footings. Average soil bearing pressure is 1,500 lb. per sq. ft. Most soils can be assumed to support this pressure without special testing or investigation.
The baffle wall outside the entrance to the shelter is extended out 7'-4" to allow storage of lawn equipment such as wheelbarrows and lawn mowers. If additional space is desired, extend this dimension.
Before starting to build the shelter, make certain that the plan conforms to the local building code. Obtain a building permit if required. If the shelter is to be built by a contractor, engage a reliable firm that offers protection from any liability or other claims arising from its construction.
GUIDE TO CONTRACTS AND SPECIFICATIONS
It is generally advisable to have a written contract with your contractor as well as specifications to supplement the drawing. A widely used and convenient contract form for construction of this size is AlA Document AI], "Short Form For Small Construction Contract Stipulated Sum," which is available from the American Institute of Architects, 1785 Mass. Ave., Washington, D.C. 20036. It would be impractical to write a specification to suit every local condition; however, the following summary of generally accepted construction materials and practices is a useful guide:
CONCRETE
For details of concrete construction, follow "Building Code Requirements for Reinforced Concrete (ACI-318-7l)." This publication can be obtained from the American Concrete Institute, Detroit, Michigan 48219.
DAMP PROOFING
Damp proofing the bottom slab is necessary to make the room more comfortable in most areas. Any contractor will be accustomed to compacting gravel and applying a polyethylene vapor barrier course. In areas that regularly experience high humidity, the outside walls of the block or concrete should be treated with a colorless type of protective coating material which is readily available at building supply stores. In areas of very low humidity, damp proofing might be omitted.
VENTILATION
Ventilation is obtained by natural convection. Air will enter the doorway and be exhausted through the holes at the ceiling. If a roof exhaust ventilation system is desired, it can be procured from commercial sources.
OPTIONS
To accommodate additional persons, increase the shelter length 2' -6" for each two-shelter spaces. Do not increase the 8' -0" width.
Lighting and receptacles may be installed with electric service obtained from a separate residence circuit. A branch circuit breaker should be installed inside the shelter.
MATERIALS LIST
Item Quantity
Concrete:
footings
4.5 cu. yd.
floor
2.3 cu. yd.
ceiling
3.4 cu. yd.
Total: 10.2 cu.yd.
Steel Reinforcing:
footings (3# deformed bars)
198 lin. ft.
ceiling (3# deformed bars)
257 lin. ft.
walls (4# deformed bars for hurricane,
tornado, or earthquake resistance) approx 300 lin. ft.
Total: 755 lin. ft.
tie wire 100 lin. ft.
Masonry:
8" X 8" X 16" hollow concrete
blocks 800
12" x 8" x 16" hollow concrete
blocks 430
8" X 8" X 16" solid concrete
blocks
75
sand (to fill cores)
12 ½ yd.
Mortar:
sand
1-1/2 yd.
portland cement
9 bags
lime
2 bags
Lumber: ("construction"grade)
2" X 4" X 8'-0" roof rafters
32 pcs.
1" X 6" ridge
26 lin. ft.
2" X 4" X 12'-0" ceiling joists
5 pcs.
4" X 6" X 8'-0" beam
1 pc.
2" X 4" bearing plate
36 lin. ft.
4'-0" X 8'-0" x 3/8"
"plyscord" sheathing
13 sheets
4'-0" X 8'-0" x 3/8"
"plyshield" soffit & ceiling 6 sheets
1" X 4" X 3/4"
48 lin. ft.
1" X 6" X 3/4"
84 lin. ft.
3/4" -1/4
24 lin. ft.
2'-8" X 6'-6" X 1 3/8" solid
core wood door 1
2'-8" X 6'-6" X 5 1/2" wood jamb
1
Miscellaneous:
15# roofing felt
4 1/2 squares
210# asphalt shingles
4 1/2 squares
½" X 8" anchor bolts
12
½" X 14" anchor bolts
2
copper screen
20 sq. ft.
6" X 6" - #10 x #10 wire mesh
200 sq. ft.
polyethylene vapor barrier (4 mil)
200 sq. ft.
gravel fill
2 ½ yds
4" butts w/screws
3
lockset
1
16d common nails
25 lb.
8d common nails
20 lb.
6d common nails
10 lb.
8d casing nails
5 lb.
exterior paint, primer
5 gal.
exterior paint, 2 coats
6 gal.
interior paint, primer
4 gal.
interior paint, 2 coats
5 gal.
