Q&A for How to Build an Underground Bunker

Waterproofing is a nightmare. Water is especially dangerous when it come to building integrity, and it's very hard to waterproof spaces underground if there isn't a building on top of it to divert water away.

It depends on where you live, but it's typically illegal to do this. Homes usually have to have windows, which means you can't put an entire house underground. For a regular building, you wouldn't be able to build it out underground to be especially large, but again, it's a moot point since you won't be legally allowed to build it.

If you know how to access it from your crawl space, it will be protected and hidden there. But you should still do some digging, as your crawl space will not be tall enough.

You may have a faulty design that was not considered safe, or you could need a better cover for it. Your city probably doesn't want a dangerous structure or one that looks bad from the surface. Your best bet is to redesign it and ask again.

Yes, you can call it a deluxe root cellar as it is underground. Just make sure to follow the restrictions for that structure type.

Concrete and metal are great radiation blockers and can survive other disasters.

Yes, you can make a small overground mudroom with windows, then a hatch to your real house underneath. Just properly ventilate your space and it should be legal.

Yes. It is the safest and easiest location to access. You won't run into property restrictions either.

See Build an Underground Bunker , Build a Bomb Shelter and related articles.

It would need extreme reinforcing and could exceed $500,000. It could be prone to cave ins if you build it wrong.

As cheap as $10,000 to as expensive as you want. A good one might cost $25,000-$50,000.

It is not the government, but robbers. The government would fill it in. Remember to keep your tools and materials safe.

You can save up for a cheaper version. You could probably build one for $10,000, if you build it right.

Yes, just get the right permits and stick to your plans. Shelters are legal types of structures.

It might take a few days if you do it by hand, or hours with friends and an excavator.

During natural (tornadoes, parasites, etc.) or manmade (bombings, nuclear fallout, etc.) disasters.

That is not optimal as enemies can find your bunker easier, but you would need less waterproofing.

Yes, it would be hard -- even dangerous -- for an 11-year-old. See what your parents think and show them your design. They may offer to build it for you.

Yes, you absolutely can. How you do this depends on your basement, but it's a good idea.

That could make a very good bunker, especially if you could use all the utilities from the old building. Here are some steps: 1. Assess your space. 2. Create a design for your new bunker. 3. Check for damage in the basement. 4. Seal any cracks. 5. Divide it into rooms (optional). 6. Reinforce the walls. 7. Install a new roof. 8. Redo all the utilities. 9. Cover it up. 10. Put in your furniture and supplies. 11. Check for anything else that needs work. 12. Enjoy your refurbished bunker.

HEPA air filters are used in nuclear power plants and hospitals. That would be your best bet. $5,000,000 would provide you with a pretty good bunker!

The materials shown above should help you keep the costs down.

Reinforced concrete and a lot of steel. You will need to make the wall quite thick.