Building a bunker is a bit extreme, but it's one way to guarantee safety for your family in case of a major disaster. Whether the zombie apocalypse is coming or not, it's never a bad idea to prepare for the worst. In places where tornadoes are common, having access to a resilient, sturdy structure can be practical, or even life-saving.
Bunkers can be used for other purposes, too—from storage, to playtime with the kids, to housing guests. An underground fortress of any size will take significant investment, though, from the design process all the way through construction.
Zoning and Licensing
Construction rules vary between municipalities, so before you even start planning a bunker, contact the zoning and construction planning offices in your county, city, or town. Ask about any restrictions or requirements on dugout structures. Some places don't allow underground structures at all.
Conduct an Underground Survey
You might never see your bunker project to completion if you fail to plan in detail. You'll need to account for every single aspect of your new lair before you start working on it. Building underground means you're likely to encounter obstacles like rocks and water. There are also the factors of space limitation, ventilation, and utility connections.
If you don't get the entire plan right, you might end up with an uninhabitable structure. Since the point is survival, you want your bunker to be as spacious as possible, and habitable for as long as you can manage. Before investing in the design, figure out what kind of soil and/or ledge you'll be excavating, and how much room you have to work with.
Carrying out a detailed survey of the ground in your backyard will tell you what if any groundwater, rocks, or utility lines are in your way. You could just start digging and find out yourself, but that's a risky proposition. It's almost certainly worth the upfront investment to retain some underground surveyors to establish how much space you have to work with.
Entrance and Escape Routes Must Be Detailed
A good bunker should have multiple entrances. You might want one to connect to your house, but at least one should lead to the outside world. You should also ensure that they are made from strong material for safety purposes.
The Big Dig
When it comes time to break ground, you may use blasters and excavators to get through hard rocks. The digging process can be done using a simple shovel if you're not in a rush. However, if you happen to be in a rush, the best way out is renting heavy-duty machinery. You can use excavators to get the dirt out and have canters transport it to the damping site.
Wall Structure and Materials
Underground structures must be made from the most durable materials. Concrete walls reinforced with steel are ideal. Steel bars play a major role in holding the concrete in place for the longest possible time. However, building concrete walls may be a bit costly if you're on a low budget.
On the other end of the scale, the most affordable material is container crates. Shipping containers can be partitioned to create an entire residential structure. If you don't have access to a container, or you wish to create your own design from scratch, you can also try using steel sheets. Simple 4-6 mm thick steel sheets are ideal—they're as strong as any container crate.
A weak ceiling structure may be dangerous to you and your family. If there's an earthquake or a nuclear explosion, the ceiling should be strong enough to withstand the tension. The best option when creating your bunker top cover is more concrete slabbing. Concrete, reinforced with steel bars and sheets can make your bunker strong and waterproof. To prevent water from penetrating the ceiling, use waterproof covers such as polycarbonate panels or steel sheets before laying the concrete on top.
Pay special attention to the possibilities of rainwater penetrating your structure. Waterproof sheets can be incorporated into ceilings and walls. Drainage mats and airtight spaces can be integrated into wall structures to prevent moisture from seeping in.
In case you are in a situation where you have to spend days in the bunker, it should be self-sustaining. Two important aspects of survival underground include water and electricity. If possible, develop a private water supply system and device an electric source apart from the grid.
If your bunker is near the water table, you can use an internal water pumping system to ensure that there is always a sufficient supply of water. You can use a generator for electricity just in case of an emergency.
Another factor you must consider is ventilation. If you have to survive underground with your family, you'll need to create room for the continuous flow of oxygen. When excavating your bunker, create space for the fresh air vent. You should also install an air filtration system to ensure that the quality of your air is as high as possible. In case of any disaster, such as an explosion, the safety of your air might be compromised. The filtration system will help you make the best of a tough situation.
You should also think about the sewer system and waste disposal mechanisms. It's a good idea to create drainage systems both above and within your bunker. You may be forced to invest in a water and sewer pump system since the bunker is built underground.
Given that the sewer will be below the municipal sewer level, you'll have to either build a private disposal point or invest in a pump. The most viable option for small families is using a biodigester, which turns waste into energy. If you have to survive underground without electricity for some days, turning your waste into energy might be the best option.