Compass Rose logo for the Compass DeRose guidesThe Compass DeRose Guide to Emergency Preparedness: Basic Shelter Info

This page was written by Steven J. DeRose in early 2003, and was last updated on 2005-10-07.

This page covers the basics of making a simple shelter, generally in your home. You may also want to read the page on expedient shelters, the page on hardened shelters, and Nuclear War Survival Skills.

The main page on emergency preparedness has links to the sections on what equipment, skills, and features you need overall. This page covers the basic walls-and-roof enclosure aspects of a shelter.

To plan a shelter, you have to decide what dangers it must work against. These days it makes sense to try to protect against nuclear, biological, and chemical ("NBC") problems. That's most of what this page is about. But don't forget the more likely and common dangers: hurricanes, tornados, floods, power outages, lightning strikes, fire, being snowed in, hazardous materials spills on a nearby railroad or highway, and the like. And don't forget the even more common and even more easily overlooked dangers of the modern home: gas leaks, stove, furnace, or clothes dryer fires, and so on.

So, before you even start spending time and money on protecting yourself against uncommon threats, make sure you take care of common ones:

In short, be prepared as the Boy Scouts say.

Once the basics are under control, then start improvements for non-basic emergencies -- gradually. Test yourself by turning off the electricity for a day, or refusing to use your car, or spending one night in your best approximation of a shelter room. Keep notes on what you lacked or wanted. Camping is great practice as well, since it simulates being cut off from the technology infrastructure. If you can live out of a backpack for a week, you shouldn't have much trouble figuring out what you need to live in a single room shelter for a week. If you don't know how, then learn (this approach also has the important advantage of being fun).

Make a list of everything you think you might want to do to prepare your shelter, with ballpark cost estimates, and what it's useful for. For example:

Improvement Cost Guess Benefit Simple steps
Water supply $50 Useful in storms, utility outages, floods, some chem/bio attacks. 1 gal per person per day; 14 days? A bottle of bleach to purify with. Learn how to get water from water heater.
Stock way ahead on non-perishable foods you eat already $150 As for stocked water Peanut butter; crackers; dried/canned fruit, jam, flour, salt, honey; canned meat/fish
First aid $100 All the time Take a Red Cross or similar first aid course. Get a bigger kit than you think you'll need (the price isn't so different).
Strengthen house $200-$2000 Hurricanes, tornados, floods Hurricane ties, sill tie-downs, diagonal braces, extra support pillars, slope dirt up to house; have plywood cut to window sizes.
Provide for lack of electricity (light, heat, crucial tools) Variable Depending on where you are, this may benefit you often. Try a practice day without electricity. Generator (how much gas supply?). Batteries don't last. Recharging? Wind-up flashlights? 12-volt lighting/appliances? Car battery on trickle charge, or Computer UPS you can use in a pinch?
Communications $100 Don't get stuck inside with no news Radio antenna wire and phone wire into your shelter area. Radio or radio/flashlight that can do without batteries.
Heat 0-100 Furnace or gas failure Stock up some firewood; sterno fuel; safe place to build fire; matches
Low-grade bio/chemical hazards $20-2000 Reduces chances of flu, new illnesses like SARS; less annoyance from sawdust and such. Good quality workshop masks (not the same as a real NBC gas mask!), up to whole-house air-cleaner.
Basic tools for escape, reinforcement, or rescue $20-$200 Useful for lots of things Big pry bar; bow saw; hammer; vise-grips™; channellocks; shovel; rope; etc.

After you've taken care of basics, then it's time to think about the shelter itself

Find the most secure area your house already has. Consider these factors:

What will it take to seal the area off from external air, and install a separate filtered ventilation source (with a "blast valve")? Windows, doors, ducts, electrical wires and boxes, and openings of any kind each make this harder. If you're not going to go all-out and provide a filtered air supply system, you may want to choose an upstairs room, in hopes of avoiding heavy gasses.

Is there enough room for the emergency supplies you want?

How stable will the room be if the rest of the house basically falls down? Or rather, how solid can it be made against such situations? Remember that diagonal bracing massively increases the strength of frame construction.


If there's radioactive dust covering every horizontal surface outside, how much raw weight of material (dirt, concrete, whatever) is there between you and most of the dust? If you're even an inch below ground level, you're way ahead because only radioation from dust within a few feet of you has much effect; anything further away has to penetrate a lot of ground before it can get to you. Consider the lay of the land; consider dust on the roof.

I like the idea of installing a sprinkler head on the roof, that you can turn on from your shelter. You can then wash off most of that dust, and bring it down to ground level where it doesn't get such a clean shot at you. In other words, such a system can make ceiling shielding far less important.

If you choose a basement shelter, pick a back corner where the basement is deepest and least exposed. A recent FEMA publication suggested that it is impractical to reinforce existing basement walls, but I disagree. The critical stress point is where the wall emerges from the ground, and i suggest here how to strengthen that area.

Buy a couple hundred 4x8x16 solid cement blocks, and stack them to make radiation shielding on the least-defended sides of the shelter room. Make sure you have something to keep them from tipping over on you, though. You can massively strengthen a wall of stacked blocks with "bonding cement" -- it will actually be stronger than a mortared block wall, though weaker than reinforced concrete (if you use hollow blocks, add vertical rebars and fill all voids with concree). If you keep some extra blocks and a radiation meter, you can use them to add protection as needed. Full bookshelves, tanks of water, or anything else very massive also makes good shielding.

Better, put in real brick, block, or cement internal walls -- just make sure the floor and foundations can take the weight (this will likely require some new footings, and a couple thousand in services from a structural engineer to be sure your work will be safe and legal).

Reinforce the ceiling over your shelter. A beam down the center will make the effective span of the rafters half what it was, vastly increasing their strength. Use hurricane ties to make sure the ceiling doesn't get lifted right off. You can keep an extra screw jack (or "lally column") handy, or a pre-cut 4x4, to lend the added beam even more strength when needed.


Make sure the doors, air ducts, and all other openings (not to mention the walls!) are designed to handle a 30psi pressure shock, followed by a negative pressure shock. 30psi is a lot: a 2x2 foot opening has 2x2x12x12 = 576 square inches of surface area, or in effect a total force applied of 17,270 pounds. Think of dropping about 8 cars onto such an opening at once to get the general idea. Even if the door material is plenty strong, consider what it in turn presses against, and how it's attached, and how much overlap there is, etc.

Make sure you know how you will get out of the shelter, for example if the rest of the house collapses. It is wise to have 2 separate air intakes, 2 separate air outlets, and 2 separate exits (some of these might be shared; for example an escape tunnel or hatch with an air outlet built into it). It is also wise to keep tools like a sledgehammer, saw, and shovel within the shelter area.



Warning: Chemical weapons are designed to be heavier than air; many hazardous chemicals that could be accidentally spilled are also heavy. In either case, they'll drift toward low areas, like basements. So the downside of a basement shelter is you're a prime target for poisonous gasses. Plan for this when sealing the shelter.

The key issue is to avoid letting any gases in except through an adequate cleaning and filtration system. The sure way to keep other gasses out, is to pull in enough filtered, cleaned air so that whatever hidden leaks you missed will be letting the clean air out, not dirty air in. If you have too many leaks, this "positive pressure" will be hard to maintain. So go over every surface in detail, find every opening, and caulk it. Don't use cheap caulk that will dry and pull away. Use flexible latex or silicon caulk with a long life. Expand-in place foam sealers are good, too.

For bringing safe air in, there are some nice systems pre-built with the right filters, a blast valve to protect the filters from over-pressure, etc. See for example the Andair "Safe Cell" unit, available at American Safe Room.

Some places to check:

Other references

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