Preparing for Nuclear war – the 15minute shelter

The reality is that most people will do no preparation before a nuclear attack, especially a pre-emptive attack as seems likely.

Assuming we hit the ground

Hit the ground!

Still not doing it?

Then you have a high chance of avoiding the serious burns. If you survived you were not affected by the blast wave. And, you now have at least 15minutes to prepare a shelter to save your life from deadly radioactivity.

It’s simple if you have a cellar … that’s where you go.

It’s simple if you know some underground place you can get into within 15minutes. That is where you go

If however, you live on a boring estate of modern houses none of which has a cellar and the only underground space anywhere near is a pub with doors built like a fortress to keep out the most determined intruder. You have a problem.

This article is to explore what is possible in 15minutes.

Sensible approach

I’ll start with the boring answer, which is there is no way on earth that one person can build a shelter from scratch and equip it, unless they happen to have a working excavator and can dig out something in five minutes. Alternatively, if you happen to already have a purpose made hole.

And it’s not as if there’s not a lot else to do. There’s the original ground level all the water containers to fill (which you just happen to have lying around .. no?), whilst gathering bedding, warm clothing, food, cooking, toilet, washing things. And then you have to get them all into the hole and cover it over with a roof that stops dust and better still has earth on it.

Realistically, the only sane approach if you only have 15minutes is to find a space in your house that is least exposed via windows and doors to the radioactive fallout lying on the ground around your house.

Mad hatter approach

But let’s indulge my madness. You have a wife partner … we assume they will do everything else that is needed (they are a miracle worker). You have 15minutes, what do you do?

Let’s be honest, none of this is possible in 15minutes, but you might manage something if the wind is travelling 30km/h and you are 30km from the epicentre. That suggests you have an hour, but I wouldn’t bet more than 30minutes.

Also, remember, the very first minutes of the fallout are by far the worst. No “I’ll just finish this” … when it comes, you have to be in the best protection you have at that time, no matter how bad it is.

The only place that can give anything like good protection is the soil. And, unless you have an excavator or a purpose made hole, you have to dig one. Realistically, even a fit purpose is going to struggle to dig more than one spade deep by a couple of square meters in 15 minutes.

Find the place

The ideal place is grass, with two things sticking out the ground onto which the tarpaulin can be strung, which aren’t trees which will collect fallout dust. And, obviously close to the supplies (we don’t want to overstress the wife who’s got the easy task). It also must not be overlooked by any land. So don’t put a shelter in a steep sided valley. If the ground where the shelter looks onto a 1 in 3 rising slope, then if sidewards on, a 3ft wide trench has to be 1foot deeper for the same protection. If end on, then a 8ft long trench has to be 2’8″ deeper (80cm). Even looking end on to a 1 in 16 rising slope requires an extra 6″ depth.

Put up a simple but large cover

Basically, you start by putting up a large tent. This will sound mad as tents don’t attenuate radiation. It’s certainly not recommended in anything I’ve seen. The reason is two fold:

  1. To cause any fallout dust to settle well away from the shelter
  2. To attempt to produce an air/wind tight space for the first 12 hours and reduced air flow after.

But although it does keep the fallout further away and it does reduce dust breathed in, it does nothing to stop radiation directly. To do that we have to get below ground.

You need a tarpaulin with a slope sharper than 45degrees, which will cause any fallout dust to tumble down the tarpaulin onto the ground at the far side of the wall you are about to build. That wall is going to be 3x4m and so the tarpaulin has to be something like 5x 8m with the edges buried to stop air flow. Likewise the ends have to be taped up. You also need a line strung up so the “ridge” is over 2m high. And, you don’t want it blowing down in the wind. So, keep it robust.

Realistically, unless you are practised and have a place prepared to hang it, putting up the tarpaulin will take the entire 15minutes. But it means the ground under the tarpaulin will not be contaminated by the fallout. It also gives your wife has a place to put her supplies.

Ideally, the tarpaulin should be dug into the ground so that no air flows through with external trenches to take the dust. Yes, that does mean you will suffocate, but not for a few days and not until after the fallout dust has settled and is far less likely to be blown into your shelter. You should be fine for the first 12 hours, during that initial period every hole to the outside should be taped over.

After 12 hours, you can add ventilation, but on the down side of prevailing wind.

Break down your neighbour’s fence

Addendum: After thinking about it, I’ve realised that when constructing a very quick shelter, there isn’t a lot of point having a roof. (see end)

You need stout timbers ideally 6-8foot long and material to support earth between the stout timbers. Fence posts are adequate supporting struts, fencing material can be spread over them to support soil. Alternatively a carpet. If you don’t have fence posts, then stout wooden doors will have to do.

Realistically, unless you are a builder with gorilla arms and a crowbar, this is never going to take less than 15minutes. But let’s assume you are a gorilla (and your neighbour is away).

This material now needs to go in the tent, but out of the way from where you are digging. I am not sure how the large sheets of covering material go in. A carpet roll is easier to imagine. At this point, all the material should be in the “tent” and it can now be taped shut … although your wife, who is no doubt having a cuppa as she finalises the packing before moving for the rest of her life, might have a view on the subject.

Place four fence posts around the hole to mark the inner edge of the wall you will make. There should be a 1ft gap from the inner edge to the edge of the shelter trench. (A 3ft wide trench, the distance inside the walls is 5ft. Place the remainder of posts at one end ready to be lifted over the hole as supports for the roof. Ensure the struts go at least 6″ beyond the line of posts, otherwise there is nothing to hold them up!

Dig a hole, roof it and get in

The hole is 1m (3ft) by ~2.4m (8ft). Start by removing a strip of  turf down one side of the hole and place it just beyond the poles at the side to form the wall with the gap of 1foot from the edge of the wall to the edge of the shelter trench. Do the same at the other side. The shelter trench now has a line of turf down the centre. Use this to build the wall at each end (leaving a 1ft gap). Now finish removing turf and building up the surrounding wall as high as you can. The end walls should be about a fence post higher than the side

Now dig down till you have a space just big enough and deep enough that all the occupants can get in below ground level before the fallout

Place the stout timbers across from one wall to the other, put the roofing material on it, get all your supplies under the roof (not necessarily in the hole) …  now get in a lie down.

… before the fallout!!

You have to get into the hole before the fallout, so no matter where you have got to, you get into whatever hole you dug. And, then you work whilst lying in the hole. BELOW the original ground level or if you can’t get below, as low down as you can get.

If you’ve done the above in plenty of time, what to do now you’re twiddling your thumbs?

If by some miracle, you finish the shelter in 10minutes, the wife has stocked the entire kitchen supplies in it and there is still room to get in. What do you do with the remaining time?

Don’t work in the shelter. Instead as long as there is no chance of fallout on the soil, take earth from around the shelter and extent out 1foot and cover the roof with as much soil as the timbers will easily support. But do not overstress the roofing timbers. Whatever you do, do not use soil that has fallout on it for this.

On the roof, you leave a gap of about 1foot at the end so you can get in and out … find something that makes a simple “hatch” to cover this, but leave it open with the hatch where it can be flipped over to cover, so you have light. You probably won’t use the hatch, unless the tarpaulin gets damaged and dust gets through it.

Finish the shelter

The fallout has arrived, and you have to give up all external work and get into a shelter that I said should be 1foot deep with 1foot walls, but strangely it has shrunk. Tough luck! Did I mention to stay in the bit below the original ground surface?

Get in and now start digging down. Your first priority is to fill all the gaps you left in the wall (through which daylight is pouring). Then you fill the gap between the wall you created and the trench top. If you can squeeze it over the top, do that as well. By the time you have filled the void around the top edge of the hole, the hole you are digging should be an average of about 2foot deep, but it would be better if it were 1ft at one end and 3ft at the other. Half a hole 3ft deep is far easier than a whole hole 2ft deep. With the roof 1foot above the original ground surface, you could have a hole 4ft of headroom. A palace! But only if the walls are straight up to the roof. More likely they will probably be sloped. That halves the protection at the top and so you should keep your head below the level of the original ground surface.

Once you’re in the shelter, work will be slow, particularly if you don’t have short spade like an entrenching tool. Once the gap around the top of trench under the roof is filled, you then have to throw material out of the hatch and onto the roof.

Sky back scatter and dust-to-ground radiation

This trench shelter is very good at stopping radiation from fallout lying on the surrounding ground, but the protection in the trench is much less effective for any body part above the level of the old ground surface (albeit far better than a house) and even 6″ of soil on top gives very little protection from back scatter from the sky and radiation when there is fallout in the air (albeit 6″ is still far better than a house). The deeper and narrower the trench, the more it protects from sky radiation. The thicker the roof soil, the better. But the very worst radiation occurs at the very start of the fallout. At that point, your entire body must be below the ground surface, ideally well below it, if the trench is too shallow or small to work, don’t work. Leave it 12 hours and then restart.

You really want as much soil on top as you can. Your immediate focus is not a living space, it’s a way to get below ground, ideally with soil covering that place. The smaller the hole you need to dig, the quicker it will be to get down and the deeper you can go so the more protection you have.

Absolute minimalist 15min shelter

This is an existing hole with a sloped surface above to shed any dust. The hole needs to be deep enough to get your body below the ground surface. The surface is sloped and large enough to cause falling debris to tumble onto the ground at least 1m beyond the hold. So, basically it is putting up a tent over a ditch or drain.

If you don’t have a tarpaulin, drive a car onto a ditch and get under. Once under, start digging down and filling in the ends and the gaps between the ground and the car base. Remember to fill around the wheels, because rubber is very poor at stopping radiation.

The problem with this approach, is that you will quickly run out of clean soil from within the trench and/or risk the soil collapsing. Also, a ditch has a tendency to fill with water.

Ways to speed it up

If you have premade walls that are just far enough apart to place stout fence posts so they just rest on the end, and they happen to be 1-2ft high, and you happen to have fence posts ready with sheeting ready, You can place the posts, place the material and get in and then start digging from inside. But you still need a tarpaulin which sheds fallout beyond the wall. In this circumstance, I would start digging from one end to make the minimum size hole you can just lie in crouched. Now dig down and place the soil inside the wall (it needs to go all around, or soil piled to make ti go all around). Just before the fallout, cover over  the top and get in the “foxhole” with your body below ground level and keep digging down till you have working space and then either continue down, or work sidewards until you can lie stretched out, and then keep going down.

The main reason this speeds it up, is because you are not trying to build the wall using the top turf. The earth is just chucked against the already built wall. You also have more headroom, which means you have more space around the top into which to put material from the trench. This speeds up digging the trench, but you may run out of material in the hole to cover the roof.

The advantage to the following is that the soil within the walls is protected from fallout dust. So, you can continue working on the shelter after the fallout. That minimise the work needed to be done before the fallout.

The flowerbed shelter

Another speedy shelter is to remove all the soil from a 8’x3′ flower bed, place it around the flower bed, build it up to give walls of soil 2′ thick and then to get in. But there are a lot of problems with this type of shelter. It certainly needs a cover to stop dust getting in. But worse, the flower bed walls may well collapse if you dig down below their bottom. You also cannot continue working on the wall after the roof is on and you are inside. So, you have to do most of the work before the fallout, and then there is very little opportunity to do more.

If you are planning on surprising the wife with a 8’x 3′ flower bed, make sure the walls go down something like 5′ into the ground, or you are in some other way shoring up the sides.

The concrete base Shelter

If you have a garage or driveway, with a base created from reinforced concrete, then there is the potential to dig a tunnel under it. There is also the potential it will collapse on you. But it might be an option.

The extendible trench

If you have the time to make a basic trench before the fallout. One thing you might consider is to create a second rectangle of walls at the end of the first and to cover this over entirely. The entrance should be at the end away from this extension. This extension is just to the sides and extra end wall. But, this allows you from within the safety of the trench to extend the original trench. However, to do this, you have to burrow under the end wall, and that means that stout timbers must be laid under this end wall to support it. Also there should not be a direct line of view from one trench into the other. A zig zag with thick (2ft?) walls is required, Firstly that is because when you first break through the extension trench won’t have the thick walls, but secondly, a long trench lets in more sky radiation. Also, with long trenches you need to ensure that there is no rising land around, so that no land surface, which has collected fallout, overlooks. You must not be able to see any surface overlooking land looking down the trench.

With an extendible trench, it will be difficult to cover with tarpaulin. The best way around this, is to pile up earth on the supports or perhaps put straw or other material, and then lay the tarpaulin on top

Surrounding Trenching

Ideally, rather than the fallout dust rollout down onto the ground surface, where it could be washed in by rain, you should dig a trench so that the dust rolls into this. The trench should be well over 3ft or 1m from the edge of the living trench.

Improved Entrance

The simplest entrance to make is a vertical exit, so that you climb up above the ground. It then helps to protect those inside, if the end walls are slightly higher than the others and ideally thicker. (1m)

After you have added soil to the roof above the living space end of the trench, the exit will remain as a gaping hole through the defences. If as I suggest, you have a tarpaulin and the tarpaulin remains either wind tight, or with minimal ventilation to stop wind blowing through, then the amount of dust entering the shelter should be very small.

The problem with doing much more than building up the walls, is that you should not be leaving the shelter and it is likely you are running out of material to use.

One of the simplest ways to improve the entrance, is to get your dining room table and to place it above the entrance, leaving just enough room to get into/out of the shelter. You then cover it with as much soil as the table can support. The problem is working out how to support the table on the trench side. On this side, the soil will very likely collapse tilting onto the shelter. The alternative is a joist across the trench.

The Shelter in the earth beneath a house DON’T

Whilst a purpose made cellar is a good idea, generally, whilst it may seem a good idea, to dig into the soil within a house, it is not advisable. This is because the walls of the house create a region of stress which spreads out beneath the foundations. If you dig into this region, you could cause the house to collapse. It might be possible to do it safely, but because of the risk to people and the house, I can’t encourage it.


Writing this article I kept finding that I had allocated time to make a roof, but the roof wasn’t doing anything, because there hadn’t been time to do it. The roof dictates the walls, the walls constrain the design so that there is space to work under the roof, but the roof doesn’t do a lot, because there isn’t time to put soil on it before the fallout and it isn’t needed to keep out the weather.

By ditching the roof, the time to get the roof timber goes, the walls go, it becomes a lot easier to excavate the hole and I may be getting near to achieving an actual 15minute shelter.

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