How to build an underground room in your backyard?

How to build an underground room in your backyard?

Sometimes people get some eccentric ideas but pull them off nonetheless. Hey – whoever heard of building rooms – underground?! And no, we are not talking about basements.

Well, it may be more likely than you think. The first thought you may have about underground rooms will probably be bunkers, and you would be correct in your assumption.  For the longest time, people have sought shelter. What better shelter than what is already provided to us by the Earth? If you think about it, people have used caves to protect themselves in their times of need for the longest time and underground rooms are just an extension of that. Nowadays we have the technology to build underground and “hide” from anything that may come our way. Well – the best defense against nuclear threats is indeed nuclear shelters – whether you have seen those in the movies or in real life does not really matter as they exist and are a legitimate line of defense against some threats. Not only this, but energy efficiency is crazy in these types of buildings – as in winter the earth keeps you warm(er) and in summer the heat simply bleeds out.

Now, you may not want to build a bunker per se. You may want to simply have an underground room because – well, let’s face it – how many people do you know that have a cool room underground? It is doubtful that you would not be a or at least amongst the pioneers on that front.

So – whatever your motivation for building an underground room might be, there are a couple of steps or rules that you should keep in mind in order to make this process as straightforward as possible. This article will outline most of them, but be sure to do more research into this subject if you do end up deciding to dig an additional room.


Potential location issues

Before anything else, please be clear that this is a huge project. You cannot do this on a whim, as you may face consequences that will make you regret even thinking about it in the first place. 

One of these potential issues is how deep you are even allowed to dig. Let us assume you want a room that is at least 2 meters high (or deep, in this case). Depending on where you live, you may or may not be legally allowed to dig that deep. Therefore, be sure to check this with your local governmental office.

Secondly, the issue goes beyond how deep – you must also think about where you will be digging. Imagine digging just to strike a water or gas line - besides being a bother it will also require repair and, of course, complete abandonment of the site you chose. Therefore, be mindful of where you will be digging. Again, the local government can help you with this by providing the exact placement where these utility lines are located, so you can avoid them.

Thirdly, the location itself must be suitable for such a project. Flood zones or sandy terrain are a big red flag and will cost you your money, time, and nerves. It is imperative to find zones that have good drainage yet are not completely rocky as you will have trouble digging.


Other issues

Even after you have cleared the location, have a long think about it and if this is the right thing for you. Underground rooms have a whole swath of different issues than regular housing does. You do not want to build a room just for it to get completely drenched later due to moisture build-up. You also do not want to build a room that has bad air circulation so you cannot really stay inside for long. If you do not take proper precautions, small landslides may occur which may ruin your project or even endanger you. If you simply need a storage room, a shed is much easier to build, not to mention remove.

But okay – let’s say you are not daunted by these issues and are ready to tackle this beast. What to do?



When digging, you have two choices – either use professional excavators or do it yourself to save money. The latter may be an attractive option since professional excavation can cost a lot depending on the size of your future underground room, but it will take much longer – especially if you are lacking equipment – and may not be as precise as you want. It is also stated that imprecise digging will cause the earth to settle which will not look great later.

Never forget too, when done for the day, take proper precautions to cover up your work – ideally with a tarpaulin. You’re building a room, not a pool – an unexpected rain can set your work back for quite a while.


Shaping the room

The following depends on whether you want this room to be a proper room with stone walls or not. If yes, then your hole should be a bit bigger than you have planned your potential room to be. You can lay the blocks with no real concern – it does not differ a lot from laying blocks when building above-ground. You should tar them on the outside, especially if you live in a wetter climate. Do not forget to include ventilation in these kinds of buildings!

If not using blocks, then be sure to shape your walls into downward slopes. You want your roof to be wider than your base, so the walls will not collapse. The danger is still there but is significantly smaller. Be mindful that these kinds of rooms are not as permanent.

You can dig small holes in the walls as makeshift shelves – if you are not using blocks it is not likely you will be using any real furniture besides maybe some stools and tables, so you have to make do with what you have. Shaping small holes will provide you with space to keep your things inside the fort, yet not in the way when walking around the already small area. 

Finally – be sure to make a good plan for an entrance and an exit. More professional projects, such as the one with building blocks, will definitely want a more professional entrance with a stairway whose placement was pre-planned, whereas the less permanent ground-based shelters can simply use blocks, rope, or dugout steps.


Putting down a roof

Again – this is a matter of what kind of underground room you want. If you have decided on a professionally built room with concrete blocks, you will want a concrete roof. The best kind of concrete roof for these kinds of projects are certainly arched roofs which will steer the condensation to the sides of the building. This is done by building a form for the roof, assembling it on the roof, putting in the rebar structure, and pouring the concrete. This is not an easy job so be sure to find help. It will be well worth it since the structure will be nice and secure.

If you are not interested in this type of underground building, then you will be glad to know there are a lot of other options. You can use simple wooden covers if you have some that are big enough. Be sure to plan how you are going to lift them up since they might be heavy. Some rope put through drilled holes will do. Lastly, do not forget to insulate the wood – as if it is left in the rain for too long it will not last. Putting moss or grass on top will do the trick.

Another solution is to use a tarpaulin as roofing, although it is only recommended as a  solution to keep out the water during rainfall since if you use it as roofing on its own it can give under the rain, dirt, etc. To rectify this, put your tarpaulin on some poles or trees and slope it to drive water off it. Creating these sloped “A” structures (the basic shape of a tent) is a good way to proceed with any roof, so do not be afraid of using other materials such as wood to build a more stable and permanent “A” structure above the entrance.


Enjoy your new room

That is it. Whichever type of underground room you decided is the right for you, you are now done and can enjoy your new underground shelter. 

Be sure to pre-plan a lot before you decide to undertake such an endeavor. Building placement, type of terrain, and legal issues may all come into play here, not to mention the cost of the whole venture. Be mindful of what you want to accomplish here – if you want a permanent storage solution there are cheaper options to be sure – however if you want something different that you can be proud of and brag to your neighbors or simply enjoy life in – an underground room is certainly something you will enjoy.