29 interior living space

How to Build a Fallout Shelter

(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

24 thoughts on “How to Build a Fallout Shelter

  1. Jane

    Error msg when I attempt to access any additional pages- says there are too many redirects to make a connection.

  2. George.singleton

    Me and my mum been watching Syria on the news and were thinking could be world war 3 so I thought I really want a underground fallout shelter and also fallout new vegas got me into nukes and stuff but I want a proper birds eye view easy design anyone help

  3. jenn

    I’m thinking about building a large log home n sealed very well…log homes r considered great warm n winter cool n summer…would that b a survivable home and safe w the logs?

    1. Michael Post author

      More mass is better, so a log home would be better than a stick built home. But wood isn’t as dense as one would think.

      For comparison the following thicknesses of material provide one halving thickness: 11 inches of wood, 2.4 inches of concrete, 3.6 inches of dirt.

      Ideally you want at least 10 halving thicknesses of a material for a fallout shelter. So to get to ten halving thicknesses with those materials you’d need 9-foot thick walls of wood, 2-foot thick walls of concrete, and 3-foot thick walls of dirt.

      This also doesn’t take into consideration the roof, which would also need that amount of shielding. It might begin to make sense why fallout shelters are usually underground.

      But why 10 halving thicknesses you may be wondering? That’s really only needed if you are near a blast and subject to the initial radiation of a bomb. Fallout has a half life measured in hours, not years. So fallout decays to safe levels very quickly. So if you’re up in the woods and days away from a blast a log cabin with one or two halving thicknesses in the walls and virtually zero on the roof would provide more shielding than stick-built cabin, especially if it was raining and the fallout on the roof was washed away. But if that log cabin had a small root cellar built into a basement with concrete and/or dirt on all sides, it would provide far better protection. The occupants might need to stay inside for a few days or even sleep there for a few weeks, but the rest of the house should be fine and definitely a better place to live after the bombs stop dropping and the fallout outside continues to decay.

      1. jenn

        Thank u for the feed back I am going to build a shelter within my basement floor a plan for at least 6 people… wish me luck just have to put n air flow to it right?

      2. jenn

        Thank u for the feed back I am going to build a shelter within my basement floor a plan for at least 6 people… wish me luck just have to put n air flow to it right?

  4. jim

    Im helping a friend up north with a underground fallout shelter he wants to bury a house trailer would someone please get back to me and tell me how to do it right.and if it can be done.thanks so much.jd

    1. Michael Post author

      Sorry for the delay, I just spotted your question.

      Just my opinion, but I don’t think there is any good way to bury a travel trailer. I know that folks have done this, but the water-proofing and external forces would be just too great.

      Even a shipping container isn’t designed to take the pressure of earth pressing in on the sides and roof. It’s designed to take weight on it’s 4 corners.

      So I’d think of the shelter more like a big underground garage that you happen to have permanently parked a trailer inside – if you choose to go this route. Then engineer that garage to take the weight/moisture of the earth backfill around it.

  5. William

    Also if you do something like this take into consideration that you can double the sqft without doubling the price. Or just taking an 8×16 and adding an extra 4ft to each of the 8ft walls you can increase the sqft by 50% for very little extra cost. While it might not seem like a lot of room every little bit helps.

    1. Michael Post author

      I agree completely. The small examples I’m showing here are small to show how easy an effective shelter could be.

    2. William

      As a quick example to my above comment. Lets say a 10ft wall takes 100 blocks and a 20ft wall takes 200 blocks. So to make a 10×20 structure it would 600 blocks to get 200sqft of space. That is 2 walls at 200 blocks (400) and 2 walls at 100 blocks (200). If you were to increase the size to 15×20 using the above numbers you would only need 100 more blocks and that would give you 300sqft. That is a 50% increase in space for 1/6 of the blocks it took you to build the entire 10×20 structure.

      One other thing to take into account is that a concrete company will charge extra for half and quarter loads so it is best to build your structure if money permits to use a full load of concrete.

  6. Rick Fowler


    All of you need to look at Armor Screen as a protection for windows in earth shelter or even underground homes.

    As most of you know, one of the inherit weaknesses in building earth shelters is the windows. Unless you can afford bulletproof glass, providing real protection against high winds is a serious problem for earth shelter dwellings.

    With that in mind, consider the following:

    I have been watching the development of Armor Screen since its inception and would seriously consider it as a means of protecting the weakest part of the earth shelter – i.e., windows.

    Please check it out and consider adding it to your lists when designing an earth shelter structure.

    Here’s the link: http://armorscreen.com/

    Rick Fowler

    PS – I found out through those who have installed it on there above ground homes that they now have an “automatic” drop down system allowing the screen to robotically operate thus covering all of the windows before the winds hit the home. Is it possible to “hook up” the system with a storm warning modulator that detects suddenly changes in pressure zones warning of a potential tornado?

    Just some food for thought…

  7. William

    I was wondering what the round about cost was for you to build the size structure you talk about in this article. I’m just curious on the cost of the block and concrete to build the basic structure. I am not worried about the costs to dig the hole or beds or any of that. Just the basic structure costs.


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>