(You can also download a free PDF copy of the How to Build a Fallout Shelter guide.)

There are a growing number of companies producing readymade storm shelters and fallout shelters, but these can be expensive. The advantage of a professionally manufactured shelter is that they are typically quick to install, carefully engineered, and durable. If you have the money to spend and don’t want to do-it-yourself, seriously consider a readymade shelter.

If you want to keep your shelter on a frugal budget, consider building it yourself with concrete blocks and your own sweat equity. This approach can also give you a sturdy, safe, and flexible design while keeping the overall cost low if you can acquire some basic skills and professional assistance when needed.

In this illustrated step-by-step guide you’ll see one way to build a concrete block fallout shelter using commonly available building materials. This shelter design is presented for your information only; we are not responsible for the shelter you build.

This shelter measures 8′ x 16′, has a main entry hatch, an inward-opening emergency hatch, requires no outside power or fuel source, and could shelter four people and their supplies underground for about 28 days – which happens to be the magic number for surviving a nuclear war.

28 Day Maximum Stay

Hollywood script writers have been telling nuclear end of the world stories since the 1940’s – shortly after the first nukes were used to bomb Japan. Stories of global annilation and armageddon have sold millions of tickets at theater box offices over the years, but the reality is that 28 days after the last bomb explodes the radiation levels will have dropped to levels safe enough for survivors to return to the surface full time.

For more about decay rates from atomic weapons see The Effects of Nuclear Weapons (1977), a publicly available document published by the Department of Defense. For details on residual nuclear radiation and fallout jump right to Chapter IX which begins on page 387. You can also learn more about nuclear weapons testing on Wikipedia.

29 interior living space 30 interior from entry

Design Overview

A tiny shelter like this would not be ideal or terribly comfortable, but we wanted to show how much function could be packed inside such a small space. It has four 2-foot wide bunks. The upper bunks would fold-up and out of the way when not in use – making the main living space less claustrophobic. The lower bunks would open to reveal food and gear storage. During the day the lower bunks would also serve as seating.

Also inside the shelter would be a pre-positioned water supply, a basic food preparation area, sink, cabinets, and composting toilet. This design concept uses no outside utilities to show how simple solutions for waste, water, and electricity could be used to lower the cost and dependency on public utilities or off-grid systems on the surface. Any upgrade in utilities would add cost, complexity, and comfort.

If the option for more comfort were desired the owner-builder could rough-in power, water, and waste lines at the time of construction, and then complete those more complex and costly amenities when time and money allows. If the shelter were needed before these enhancements could be completed, the shelter would still be functional with the basics shown here.

31 interior view of kitchen and toilet


We recommend using a non-electric composting toilet, camping style porta-potti, or simple sawdust toilet for low-cost fallout shelters. These options use little or no water, often cost less than a complete flush toilet system, and when properly used create little or no offensive odors. The only disadvantage is that you’ll need to manually dispose of the waste in a dedicated compost pile or sewer dump after your shelter stay.

27 shelter access way view down

Main Hatch

One main entry with a vertical ladder would be the entry point. This shaft would be sealed off by a blast door at the bottom to add additional protection to the interior during a nuclear blast. An interior blast door is also an added buffer against raiders looking for supplies in the aftermath.

A grenade sump would be located on the floor of the shaft to help contain explosives dropped into the shaft. This sump could also act as a simple yet limited drain for water – depending on how deep your make it. If you have a high water table (ground water) be sure to seal the bottom of the sump to prevent flooding the shelter – and seriously consider a sealed commercially built shelter. A concrete shelter like this would be subject to flooding, just like a basement, in areas with high water tables.

A shower head could also be added to the area at the bottom of the shaft to help residents wash fallout off themselves before re-entering the shelter. Ideally shelter residents will remain inside the shelter during the disaster and avoid ingesting or inhaling any fallout – which elevates the risk to health tremendously.

42 emergency hatch open 41 emergency hatch

Emergency Hatch

An emergency hatch would be located in the rear of the shelter. This shorter shaft space could be used to store gear and essentials – like a closet – when not in use. The emergency hatch would only be used if the main hatch were blocked by debris or if the main shelter entrance needed to be defended. The emergency hatch would open inward, under a foot or more of sand. On the surface the emergency hatch would be completely concealed below ground but when opened, the sand would drop into the shelter allowing the residents to exit. Resetting the emergency hatch would take time and the clean-up inside the shelter would be difficult – so opening the emergency hatch would only be done in an emergency.

In the following pages we’ll take you through the steps for building this design.

Next Page

Tagged with →