Whether you’re getting ready for a nuclear exchange between superpowers or just some destructive high-wind events, there’s hardly anything more comfortable, or reliable, under those circumstances, than your very own underground bunker.
But as most preppers know by now, most underground bunkers that we see advertised are solely the province of the very wealthy: Costing tens of thousands, hundreds of thousands, or even millions of dollars, most of us normal folks will simply never be able to afford one.
The good news is that it is possible to get much of the protection, if not the amenities, of an underground bunker by building it yourself, affordably, using commonly available components.
I’ll be sharing with you one such time-tested and proven design below, based on a design found in one of the DoD booklets from the 60s.
Will This Shelter Protect Against High Wind?
Yes, it will. If there is an approaching tornado or other high-wind event, this shelter will provide excellent protection. Being partially underground at the surface level and then covered with several feet of soil, it will withstand virtually any conceivable wind speed.
Will This Shelter Protect Against Fallout?
Yes, it will. Radioactive fallout is one of the most insidious and serious risks associated with a nuclear accident or nuclear warhead detonation.
Being layered with several feet of soil this shelter will provide a modest protection factor, and includes a hand-operated ventilator to keep fresh air moving in.
Will This Shelter Protect Against Bomb Blast?
Yes, to a degree. Although shelters of this type are usually only good for about 5 to 6 pounds per square inch of pressure, that is enough to provide significant protection assuming you are not very close to a nuclear- or massive ordnance detonation.
However, if you are near ground zero or in a high-damage radius, it won’t guarantee survival.
Is This Design a Good SHTF Bunker?
No. Not only does this bunker lack any sort of secure door and secondary exit, it is not suited for a long-term habitation when you need to retreat to your bunker and live inside with all the comforts of home, more or less, as society is going to pot around you.
Also, not for nothing, the mounded earth over the bunker combined with the open entrance is highly conspicuous and difficult to camouflage against observation except from the air or from quite a distance away.
Basically people are going to know it’s there once they are close as long as they have their eyes open.
Bunker Specs
If you follow the plans below, this shelter will be reasonably comfortable for three people with 32 feet of floor space and approximately 122 cubic feet of space internally, including the short open length of the entrance tunnel.
The total surface area footprint of the bunker including the dig site and the soil you mound over top will take up a rectangular area that is about 24 feet long and 12 feet wide.
Estimated Cost
Around $1,500, not including the cost of tools, heavy materials, delivery and help if you need it. Depending on the quality and grade of the materials, and if you already have some of them, you might spend as little as a thousand dollars on your bunker or even less.
How Long Does it Take to Build This Bunker?
About a week if you are digging it out by hand and reasonably competent with tools and light fabrication.
If you are a seasoned pro at working with sheet metal goods and are excavating the dig site with multiple people are using heavy equipment, you might be able to get it done in as little as 3 to 4 days.
Before You Dig! Assess the Site
Apologies for the delay, but this is mandatory. Before you ever put shovel to dirt you must take the time to carefully assess the site where you’re going to place your bunker.
It is critical that you do not locate it in any low-lying spot that is flood-prone or any part of your property that gets lots of moving surface water during heavy rains.
Even when you’ve got that figured out, you want to make sure you orient the entrance tunnel away from any such water that might accumulate or sweep over your bunker.
Also consider the presence of any other potential hazards like buried electrical or gas lines. Think this through and use common sense to avoid costly and time-consuming mishaps.
Likewise, if possible, you don’t want to locate the bunker so far away from your house that you might not be able to reach it in time when seconds count.
Similarly, don’t locate it so close to your house that your house might get knocked down by the event that sent you fleeing in the first place, entombing you inside the bunker.
Once you’ve got all this figured out, then it’s time to grab your tools and get to work.
Tools and Materials
You need quite a list of tools and materials to complete this project, but it’s absolutely achievable for anyone with basic construction or DIY experience, and all of the tools and the components are commonly available from the usual retailers of such goods.
Corrugated Steel Pipe, 16 gauge, 48” diameter: this type of steel pipe offers an excellent combination of strength, protection, weather resistance, affordability, and easy handling. It’s ideal for our project.
You’ll need a 9-foot section which is suitable for holding three people comfortably for a short amount of time. If you have a larger group, or want greater comfort for those three, increase the length.
Corrugated Steel Pipe, 16 gauge, 30” diameter: a smaller diameter version of the above pipe is used as the entrance tunnel to the main shelter.
Regardless of how many people you have, you only need a 3-foot section of this. Remember that if you are picking up the larger pipe yourself, you can nestle this pipe inside it to facilitate easy transport.
Sheet Steel, 16 gauge: you’ll need corrugated or non-corrugated sheet steel of the same thickness as the piping above. It is used to make the end caps or “walls” of the main shelter. You’ll need enough to cut two roughly 4-foot circles, and one 3-foot circle.
2x4s: a few 2x4s, a few inches shorter than the 9-foot length of the main shelter pipe above. Two or three should be sufficient.
These form the floor joists on top of which you will lay the thin wooden strips to form the floor of the shelter, making it much more comfortable to sit or lie down on.
Wood Stakes: wooden stakes are helpful for marking the corners of your dig site. You can use any scrap wood you have at hand as long as it’s durable enough to be driven into the ground.
Wood Strips: plenty of 1- to 2-inch wide wood strips will allow you to easily lay a simple floor inside your shelter.
These don’t have to be the same length as your shelter, because you can cut them and lay them end to end and side by side to make them fit as needed. For this use, smoother is better, so don’t hesitate to sand them to make a nicer surface for your backside.
Sandbags, Large: large sandbags are used to create a retaining wall and support around the entrance tunnel of the shelter. These bags should be capable of holding about 75 pounds of soil or sand. You’ll need about 40.
Sandbags, Small: smaller sandbags are used to block up the entrance tunnel to the shelter behind you after you’ve entered it.
Considering the cramped quarters, they must be lighter so they are easy to maneuver. These bags should be capable of holding anywhere from 15 to 20 pounds of soil or sand. You’ll need about 20.
Plastic Sheet, 6mil+: heavy-duty, weatherproof plastic sheeting will give the shelter a high degree of water protection and also help keep out tiny creepy crawlies that might slip in through cracks.
Your plastic sheet should be at least 12-feet wide and 12 feet long if you’re building the standard-size shelter detailed here. If you’re making your shelter longer, the length should equal the combined length of the entrance tunnel and the shelter pipe itself.
Screen Door Mesh: common screen door mesh will help you keep bugs out of your ventilation pipe and the entrance tunnel.
Hand-cranked Ventilator Kit: a hand-cranked ventilator kit is necessary to provide fresh air while you’re inside the shelter. These are commonly sold by retailers of prepper gear, shelter kits, bunker fabricators, and other such sellers.
Make sure your kit comes with vent piping and a hood for the end of the exterior pipe, necessary to keep out rain and small animals. Double check to see if it includes a mesh insect screen; if it doesn’t, you’ll have to repurpose the screen door mesh above.
Hood for Vent Pipe (if needed): if the pipe for your ventilator does not include a hood, you must get one and install it, no exceptions.
Luckily, you can use a cheap and common water heater exhaust hood or similar component that can be bought from any hardware store. Make sure it has an adapter or is sized to fit the pipe that came with your kit.
Dirt: you’ll need lots of extra dirt to cover your shelter after you place it in the hole that you excavate, and the amount of dirt that you remove won’t be sufficient.
Plan on at least 11 cubic feet for the standard shelter plan. Clean fill dirt is adequate for mounding, but consider covering the whole thing with topsoil so that you can grow grass on it. That will help keep your soil in place by preventing erosion.
Sand: I strongly recommend you get your hands on sand for filling your sandbags. It works better, is easier to handle, and greatly reduces the likelihood of pest infestation.
½” Bolts, washers and nuts: 1-inch long, half-inch diameter bolts suitable for metal work will be needed for attaching components together if you aren’t going to weld them. See the next entry.
Welding Kit (optional): a welding kit and supplies suitable for welding your chosen steel pipe together.
Specifically, you can weld the end caps together and the entrance tunnel to the one end cap for a sturdy, permanent installation. It is not strictly mandatory, but definitely a good idea.
All-Weather Sealant: all-weather sealant suitable for use on metal will help keep moisture and insects from leaking into the shelter at connection points. We will be covering the shelter with a single uninterrupted piece of heavy-duty plastic, but this is cheap insurance.
Metal Snips: heavy-duty metal snips or “aircraft snips” can help you easily cut through the metal piping and the sheet metal for fashioning it to size and helping with connections. Though laborious, the control is unmatched.
Angle Grinder: an angle grinder will help you make quick, rough cuts through metal, saving time. You can also use it to cut off the ends of sharp bolts or screws that might be protruding inside the shelter and eliminate sharp, jagged edges which could compromise your plastic wrap.
Jigsaw w/ Metal Blade: a jigsaw is helpful for cutting out holes needed for your ventilation pipe and the one end cap where you’ll connect the entrance tunnel. Make sure the blade is rated for metal and get several because they wear out fairly quickly.
Drill with ½” Metal Bit: pre-drilling the holes for your bolts, if you are fastening the end caps and entrance tunnel with bolts, is a lot quicker, cleaner, and easier than trying to simply power them through.
Metal-rated Hole Saw Bit (optional): if you have one, a metal-rated hole saw bit that is the necessary size for the installation of your ventilation pipe can save you some grief when it’s time to install the ventilator. Again, not strictly necessary; you can use your jigsaw if you have to.
Shovel: you can always count on a shovel for moving lots of earth as long as you have the muscle. A few helpers with their own shovels will go a long way, too.
Excavator (optional): if you’ve got the machine, can afford to rent one or if you have a friend that has one and that friend owes you a favor, now’s the time to get an excavator.
Although the digging is not particularly terrible for this project, it’s still going to be a heck of a workout if you’re doing it by hand.
Yardstick: a yardstick is useful for quickly and roughly measuring depth for your excavation and other measurements besides.
Marker: Any kind of permanent marker or paint pen that can help you make spots and lines on metal. This will better enable you to measure and cut with accuracy.
Metal Scribe (optional): if you prefer or don’t have a marker, you can also use a metal scribe or other hard, pointed tool to mark your cuts and holes in the sheet metal.
Not too bad, right? And aside from the materials and a handful of tools you’ve probably got everything you need already. Now, let’s move on to the steps but before we do there’s just one more thing to cover.
Building Your Own DIY Bunker, Step by Step
Step 1: mark dig site. Once you know where your bunker is going to be located and how it is going to be oriented in the ground, mark your dig site.
Measure out a 12 foot by 4 ½ foot rectangle, and place a stake in the ground at each corner. Run string between them if you want to if it helps you stay on target while digging.
Step 2: measure and cut end caps. With the dig site marked, take the time to measure the actual diameter of your main shelter pipe, the larger one.
Once that is done, scribe or mark a circle on the sheet metal that is 4 inches greater in diameter than your original measurement. Repeat the process, duplicating another circle elsewhere on the sheet metal. These will be the end caps.
Using your jigsaw or metal snips, carefully and cleanly cut out the end caps taking care to keep them as uniform as possible. If you want to err on the side of caution, cut them out slightly oversized.
Step 3: cut holes in end caps for entrance tunnel pipe and vent pipe. With the end caps cut out, it’s time to cut holes for the entrance tunnel and the vent pipe.
Consult the instructions that came with your ventilator kit for extra guidance, but generally cutting the hole for the vent pipe just off-center on one cap will be satisfactory.
For the entrance tunnel, measure the actual diameter of the smaller pipe as you did above, then scribe or mark another circle using that measurement exactly on the other end cap (notthe one you cut the vent pipe hole in).
The edge of this marking should be about 2 inches away from the edge of the end cap. Cut it out just outside the line, then check the entrance pipe for a snug fit in this hole. Hog it out a bit if needed.
Take the time now to cut away any jagged edges or burrs on both end caps.
Step 4: attach end caps to main shelter pipe. With your end caps completed and finished, establish which side of your shelter pipe is “up”.
You’ll install both end caps on the shelter pipe with the holes you cut out biased “up” (said another way, at 12 o’clock) relative to the shelter. This is critical!
If you are welding the end caps in place, spot or fully weld them. If you are bolting them together, make a series of cuts around the edge using your metal snips, each about 2 inches long, to form tabs that you can fold over on the shelter pipe.
Make 12 such tabs evenly spaced around the circumference of each end cap. Starting on the tab side, drill a hole through the tab and through the metal of the shelter pipe.
Run the bolts with washers through the holes and secure with nuts.
Step 5: attach entrance tunnel to end cap. Double-check the fitment of the entrance tunnel to its matching hole in the one-end cap. If the fit is good, protrude the entrance tunnel about 2 inches into the body of the shelter, then weld in place.
If using bolts, use your metal snips to create 12 more tabs as before in the prior step, then drill, insert the bolts with washer, and secure.
Step 6: cleanup sharp edges with angle grinder. Take the time again to go over all of your connections and modifications, judiciously using the angle grinder to cut away any jagged edges that could snag you or the plastic cover you’ll be putting over it later.
Step 7: Seal all connections with sealant. Once you have deburred the shelter and all connections, use your sealant to close up all gaps for better security and moisture resistance.
Step 8: excavate hole. Now it is time to dig. Using your shovel or the excavator, dig out a 9-foot length to a depth of 2 feet. Remember that you’ll need to dig out a longer run if you are using a longer pipe.
For the remaining 3 feet of the dig site, only dig it out to a depth of 6 inches. This shallow depth will be needed to support the offset entrance tunnel.
Step 9: place and support shelter. Carefully maneuver and lower your assembled shelter into position, placing the main shelter pipe into the deeper section. If it won’t fit, don’t force it and risk crushing or warping; just excavate a little more dirt until it will.
Once it’s resting on the bottom, carefully rotate it to make sure it is upright and level, and that the entrance tunnel is likewise resting in the end of the site.
Double-check and make sure that the hole you cut in the opposite end cap is clear of the surface and not obstructed.
Step 10: install ventilator kit. Run the pipe and mount the unit with handle according to the instructions that came with your kit.
Don’t forget to put your screen over the end opening if the kit didn’t include it. If you need to climb inside your shelter at this point, do so carefully because it’s not fully supported and might shift.
Once the ventilator is installed, move on.
Step 11: cover shelter with plastic sheet. Take another moment to double check every installation so that it is satisfactory and sturdy.
Once you’re happy with it, unfurl your plastic sheet and cover the entirety of the shelter, from the end of the vent pipe where it rises (if applicable) to the end of the entrance tunnel.
Your plastic sheet should drape all the way over and touch the ground on both sides of the shelter inside the excavated pit.
Trim where necessary, and be very sure that you don’t cover the end of the vent pipe. Inspect for snags, tears and rips, addressing them and, if necessary, using a new sheet of plastic.
Step 12: backfill. Now take the excavated soil and additional soil where needed to backfill around your shelter for maximum support. Carefully support the vent pipe from beneath before covering it with soil, and work carefully to make sure the entrance tunnel is fully supported.
Bring everything back up to surface level, then tamp and add more soil if needed.
Step 13: install shelter flooring. Carefully slide your 2x4s inside the shelter at this point. Pre-cut them to just a couple of inches short of the length of your shelter pipe.
Positioning them inside the shelter evenly spaced on the bottom, blocking up the middle one with scrap wood or another 2×4 if needed to make a level surface.
Then take your wood strips and lay them over the 2x4s perpendicular to them. Arrange them so that you create a solid floor from edge to edge and end to end in your shelter.
Step 14: fill sandbags. Fill your large and small sandbags with sand. A sandbag should only be filled about 3/4 of the way at most with sand so it is flexible and deformable for maximum strength.
Step 15: place small sandbags inside shelter. Load your small sandbags inside the shelter at this time, stacking them neatly near the entrance tunnel. You’ll use these sandbags to block up the entrance tunnel behind you and take cover in your shelter for real.
Step 16: layer large sandbags around and over the entrance tunnel. Place the larger sandbags as retaining walls on either side of your entrance tunnel.
The retaining wall should be two sandbags long on either side, parallel to the entrance tunnel, with about half of one sandbag extending past the entrance of the tunnel. Make sure you leave a “flap” over the entrance that can be easily and quickly lifted for entry.
Stack them up on both sides, then create a “bridge” going across the top of the entrance tunnel to join the two walls. Make the bridge at least three layers high. Make sure all of the sandbags are stable, then move on.
Step 17: cover shelter with dirt and mound. Cover the entirety of your shelter, including the top of the entrance tunnel, with a layer of soil that is at least 2 feet deep or thick on all sides.
Add the soil carefully until you have the plastic fully covered to prevent tearing. Gently tamp as you go. DO NOT USE HEAVY EQUIPMENT TO TAMP YOUR SOIL OR YOU WILL CRUSH YOUR SHELTER.
And just as a reminder, make sure you don’t seal the entrance to the shelter by weighing the plastic down in front!
Step 18: check depth. Check everything to ensure you have the required 2 feet of soil on all sides. You can check the depth easily using a piece of stiff wire as a probe that is marked at 2 feet.
Remember: this soil covering is absolutely vital for protection from wind, radiation and blast effects. Check it and do it right!
Step 19: install screen mesh in entrance tunnel. Cut out and install your screen mesh inside the entrance tunnel to keep bugs out.
You might want to hang up a couple of overlapping layers at the entrance and then another set where the tunnel ends inside the shelter for maximum protection.
Step 20: finished! Your DIY bunker is finished and ready to use. If you have to take shelter inside, get yourself and your family in and then use the sandbags you pre-placed inside to block up the entrance tunnel behind you for maximum protection. Practice makes perfect here!
Maximizing Longevity
You can expect your underground metal pipe shelter here to last about 10 years assuming you have cited it properly and it is not subjected to any destructive events such as major flooding or something heavy driving over the top of it.
If you want it to last longer, consider investing in higher quality steel pipe, or even having it weatherized by encapsulating it in various metallic or synthetic coatings that will resist rust, abrasion and other wear and tear.
Also, keep in mind that even though this design is proven and has been around for quite a while, if you have the money, you might consider investing in a similarly-sized subterranean shelter module that is purpose built for the task.
Shelter modules of this other type can last 20+ years when set up correctly.
Tips, Tricks and Improvements
Increase length for more people or comfort. If you want room to lay down, room for more people, or just more comfort, make the shelter pipe longer. You’ll have to make the 2x4s longer to support the floor, and you’ll need more plastic wrap and soil for coverage, but every other step stays the same.
Cover with more soil for better blast and fallout protection. If you want even better blast and fallout protection, add another foot of soil on all sides.
Grow grass on your soil covering. I urge you to get grass growing on your soil covering as soon as possible. It is vital to keep the soil in place long term since the root system will prevent erosion by wind and rain.
Make use of underfloor storage. You’ve actually got a little bit of useful storage under the floor of your shelter, easily accessible by simply lifting up a few of the planks. It’s more than enough to stash some clothing, blankets, food, water, and the like.
Think twice before covering the entrance with a door or panel! Time may be of the essence. I know it’s tempting to craft some kind of covering or door for your shelter entrance, but keep in mind that if it gets stuck or you can’t remove it in time you might be trapped outside with no protection when the fateful moment arrives.
Tom Marlowe practically grew up with a gun in his hand, and has held all kinds of jobs in the gun industry: range safety, sales, instruction and consulting, Tom has the experience to help civilian shooters figure out what will work best for them.