How to Build Underground Bunker | Design and Floor Plans (2023)

If you’re thinking of building a safe haven inor near your house, hold off on digging a hole and constructing an undergroundbunker right now. In the end, a bunker might kill you.

Having a basement or cellar in your house mayprovide greater safety during an emergency. What should you do to prepare yourbasement to serve as a safe haven in an emergency, and what problems can youavoid?

Here’s a step-by-step guide to repurposing your existing basement into a safe nuclear fallout shelter. Let’s begin!

#1 Inspect the Foundation

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Having a safe haven in your basement is agreat idea for a disaster preparedness scenario. Just step downstairs and closethe door behind you if things feel a little shaky.

You need to make sure that the basement is structurally sound before using it as a safe place to stay during a natural or man-made catastrophe.

You may clean yourbasement from floor to ceiling by clearing off the clutter. Watch out forsymptoms of structural instability, such as sagging drywall or cracked floors,as well as any indications that water is seeping into the area. If yourbasement collapses in on you at the first indication of danger, you don’t wantto be stuck there with your emergency supplies.

If you’re not sure what to check for, you may want to contact the expertise of a contractor or building inspector. Bringing in an expert is never a bad idea, particularly if your safety is at risk.

#2 Take Care of Underground Moisture

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Because water may leak through the walls, basements are notoriously wet. In addition, since this area is often located below ground level, water tends to accumulate here rather than evaporate or dry.

If you want to utilize your basement as a survival bunker, this might be a major issue.

Mold and mildew may growin the basement if water is left unattended for a long time, which could bedangerous to anyone who is sheltering there, especially those who haverespiratory problems like asthma or chronic obstructive pulmonary disease.

Water in your basementmay originate from a variety of sources, including water breaches in the wallsand even the surrounding air. Find the source of the water and strive to stopit.

To avoid replacing yourdrywall and insulation because of leaks in your concrete walls, you shouldfirst strip the walls and paint them with a waterproof coating. Considerpurchasing a dehumidifier to keep the area dry if humidity is a problem.

It’s important to remember that beginning with a strong, secure atmosphere is essential if you and your family ever need to make use of your basement as a survival bunker.

#3 Install NBC Air Filter Systems

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Bringing in air from the outside might be deadly if you’re evacuating after a nuclear explosion or if you’re dealing with an airborne virus danger.

A self-contained air storage and recycling system or a set of great filters will need to be used in these situations to make sure that the air in and out of your building is safe to breathe.

If you’re serious about having an air filtration system that can withstand the devastation of a nuclear catastrophe, I recommend consulting with an expert. Castellex has extensive expertise in the design and production of NBC (Nuclear Biological Chemical) air filtration/air supply stations for various uses.

An NBC system by Castellex is intended to pull air from outside, filter it, and release it into an enclosed room with enough force to provide positive relative pressure. Let’s take a closer look at NBC filter use and advantages:

  • The military uses CBRN, which stands for Chemical, Biological, Radiological, and Nuclear, as an abbreviation for weapons of mass devastation.
  • A bomb shelter air filtering system was included in the system from the beginning. Intake hoses for room air filters have been available for purchase as a kit. Avoid them at all costs. Room air filters can’t be upgraded to NBC air filter systems.
  • It filters particles (such as radioactive fallout and biological aerosols) as well as gases over a wide range (chemical weapons and industrial accidents). It is common for activated carbon to be coated with chemicals to make it more resistant to high-volatility warfare gas emissions.
  • It brings in a clean outside air. The filtering system has an intake tube for bringing in outside air.

Air within the shelter ispressurized to a greater pressure than the outside air while the filter is inoperation, making it more stable. If there are any leaks, the filtered airwithin the shelter will flow outward, preventing unfiltered outside air fromentering the shelter.

Your shelter’s seals ondoors and hatches should not leak if there is no “overpressure.”Unfiltered (and potentially dangerous) outside air may enter the shelter onlyif there is excessive overpressure.

Air recycling and qualityare two of the most important considerations when converting your basement intoa safe haven. For the record, you may go days without food or drink, but justthree minutes without air will cause you to perish.

#4 Match Your Shelter’s Air with The Earth’s Atmosphere

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Carbon dioxide comes from human breathing as a byproduct.

Approximately 20% of the atmosphere is made up of oxygen, and the remaining 0.04% is made up of carbon dioxide.

To survive, oxygen levels must remain above 19.5 percent (195,000 parts per million).Both low oxygen and high carbon dioxide levels should be monitored in your shelter, and alarms should be installed.

There is a lot of cheap carbon monoxide (“m”), but we’re talking about carbon dioxide (“d”) when discussing ventilation. Make sure you grasp this distinction. For emergency shelters, the following equipment is highly recommended:

  • a thermometer;
  • a humidity gauge;
  • an oxygen depletion gauge;
  • a smoke alarm;
  • a low carbon monoxide detector;
  • a carbon dioxide alarm;
  • and a radon detector.

These instruments may be integrated into one unit if there are more than three of them.

#5 Determine Your Water Source

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The next step is to beginstocking your basement with emergency supplies after it has been made secureand equipped to withstand a disaster. Your survival region is a place where youwish to stay for as long as possible if you can.

Water shouldn’t be a problemas long as the air is safe. In a survival scenario, the typical person requiresone gallon of water every day. The other half is used for personal hygiene,such as washing your hands and brushing your teeth.

You have a fewalternatives here, but municipal water is likely to be hazardous orunavailable, so it’s a good idea to have another source of water. A basementwell may not be an option, so you’ll likely need to stockpile enough water foreveryone in the home.

The plastic bottles or jugs that the water comes in are more than enough for short-term storage. In the long run, you’ll need something a bit more substantial and cost-effective. A waterBOB or 55-gallon drum is a preferable solution for storing tap water.

With a waterBOB, you can store water in your bathtub without having to worry about spills or odors since the bag holds 100 gallons of water.

To guarantee that yourwater is free of toxins, be certain that it has been treated. Having to copewith an apocalypse only to discover that your water is contaminated with algaeor other germs is the worst possible outcome.

As a side note, I have a number of videos on water storage that may be helpful. The various free resources on water acquisition and purification are also worth a look.

#6 Assemble a Food Storage (or Freezer)

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Food preservation is thenext topic on our list. The foundation of every survival room, including theone you’re constructing in your basement, is a store of emergency food.

With an adequate foodsupply, you won’t have to scavenge around the post-apocalyptic wasteland thatwas once your home. A well-stocked emergency food pantry should include canneditems, bulk dry goods, and even freeze-dried meals.

Avoid dumping all of yourequipment into a corner. For a long stay, you’ll need a thorough inventory anda method for keeping track of everything you’ll need. To avoid wasting food,you’ll need to set up your kitchen like this. You may rotate expired items intoyour normal pantry and use them up while replenishing your emergency stockpileas they near their expiry date. Good shelving may help you make sense of youritems and keep them neatly arranged.

It’s important toremember that canned and dried foods are weighty. When it comes to organizingyour emergency supplies, a cheap set of shelves from Walmart isn’t going to dothe trick.

You may either buy someheavy-duty shelves or make your own, to guarantee that your food storage issafe. When possible, use anchors to attach your shelves to the wall, floor, orceiling. This is especially important if you live in an earthquake zone.

Cooking using typical off-grid techniques like camp stoves in your basement is not recommended since it is an enclosed room and the carbon monoxide will build up, which may be dangerous. If you are unable to leave the house, MREs and canned food that has not been cooked may be substituted for proper cooking.

#7 Try In-House Farming

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After a few weeks of dryrice and beans, you’ll certainly be yearning for some fresh food. If you’resettled in for a lengthy stay in your basement, you may want to look intoproducing some food.

This achievement may seemimpossible. How can you grow plants without sunlight? You’ll never know untilyou try.

All you need is a decentsupply of water and an off-grid power supply to keep your grow lightsoperating. With those two items, you can grow practically anything underground,as long as you’ve got the area for your plants.

In the case of anythinglike a nuclear attack, this becomes much more vital. Depending on yourcloseness to the fallout, cultivating crops in the soil surrounding your homecould be difficult.

Many plants absorbradioactive isotopes from the earth, which contaminate the fruit and make itharmful to consume. Following a nuclear meltdown or strike, some of the isotopesleft behind look a lot like the micronutrient’s plants get from the soil.

Hydroponics and aquaponics systems are particularly suited to indoor and subterranean conditions since they utilize water instead of soil.

Aquaponics may also incorporate fish. The plants filter their water, and in turn, the fish excrement functions as fertilizer for the plants.

Set up a few solar panelson the roof to keep your grow lights working, and you’ll find producing food inyour basement a lot simpler than you may expect.

Meat, fruit, veggies, and dairy should be purchased in free-dried #10 cans or something comparable. It’s a bit more costly, but the quality of the food is excellent, it takes up little room, and it will endure for a long time to come. Because freeze-dried food has to be rehydrated, you’ll need to stock up on more water than you would if you were storing fresh food.

#8 Keeping Yourself Clean

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Hygiene is critical in acramped location like a basement, particularly if it’s used by a large group ofindividuals. Bathing, brushing one’s teeth, and going to the restroom will allbe necessary. Many completed basements include bathrooms, but if the grid failsand you lose electricity and water, your toilet may be rendered worthless aswell.

Wet wipes and wash rags mayhelp keep your body as clean as possible in the absence of showers, so stock upon the latter if showers are out of the question.

A 5-gallon bucket with a cover and a clean plunger may be used to build a DIY washing machine, and then the clothing can be hung out to dry.

#9 Give Yourself Several Ways Out

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Your basement survival bunker isn’t the place you want to be stranded if the rest of your home falls on top of you.

Keep various escape routes in mind while planning your basement survival bunker—just in case.

At the very least, mostbasements have two ways out: a door leading to the house and a door leading tothe backyard. In certain cases, you may also be able to open the window.

In a situation, it mayfunction as an escape route despite its high location on the wall. To get toit, make sure you have a sturdy ladder with a wide enough opening.

If your basement only has one exit, add a second one on the opposite side of the room from the present one. If you ever need to leave your survival bunker, make sure you have numerous exits planned.

#10 Add Insulation to Help Regulate the Temperature

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How would your basementfeel if the grid went down and you were suddenly left without electricity fordays or weeks? Being buried far beneath provides a small amount of temperatureregulation.

This doesn’t mean thatyou won’t have to deal with hot summers and freezing winters. The outsidetemperature will get into your house and survival shelter.

Don’t forget to add some insulation to the walls and ceilings while you’re fixing and strengthening them.

Adding insulation to the basement walls, as well as the soil that surrounds them, will make it simpler to keep the temperature stable.

You may use this set-upto safeguard your food supply as well, since even food can be harmed by veryhigh temperatures.

You’ll also want to make sure you have adequate blankets, sleeping bags, and clothes on hand so that you don’t have to turn to potentially dangerous DIY ideas that might emit lethal carbon monoxide.

#11 Maintain the Shelter for Emergency Preparation

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Sheltering in place is afantastic choice if you’re far enough away from the tragedy that might spellthe end of civilization as we know it. Having a basement makes things evensimpler.

When deciding whether ornot to take cover, use caution. Decide when to shelter in place and when toflee, and be prepared for either scenario. When it comes to the end of time,it’s better to be prepared rather than caught off guard.

Basements don’t have to be damp, cold, or uncomfortable places to take refuge. With a little forethought, you can transform your basement into a safe haven for you and your family in the event of an emergency.



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Every prepared personshould look into how to build a ground bunker. It is something that we can’t ignore,even if it’s out of reach for most of us financially. Escaping and avoiding thenuclear fallout and other disaster might be your top priority someday.

In any case, you’ll be safe and sound in a bunker under the surface. There is a lot of work involved, but the end result will be worth it in the long run, even if it takes some time.


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