Tornado/Storm Shelter - Underground

Ghost River Retrievers · May 6, 2025

It seems that we are now in "tornado alley." Last month a series of tornadoes tore through our area, with massive destruction and loss of life. One came within a mile from our home.
It's time for me to seriously consider constructing a shelter for people (and a few dogs). Probably around 100 sq. ft. will provide the space we need. Due to my wife's concerns about appearance, it needs to be underground (frankly, those seem safer to me anyway).
Have any of y'all build an underground shelter ... or had one built?
I've looked at the pre-fab shelters and they're pretty pricey, even without installation, which is why I'm considering building one or contracting for one to be built.
Factors that I know to be conscious of:
* level of the groundwater
* sturdy door
* ventilation
* lighting (I may put a generator in a hole nearby which could be used for electricity if necessary)
If built for lengthy storm:
* storage for a little food & water
* potty

I appreciate any thoughts, particularly (but not limited to) those from folks who have underground shelters.

Thanks,
GRR

bcp · May 7, 2025

Due to my wife's concerns about appearance, ....

Your wife probably wouldn't go for the increasingly popular idea of burying an old school bus.

buried school bus shelter - Google Search

Neither would I.

Maybe start with prefab box culverts.

prefab box culverts - Google Search

Bruce

redman135 · May 7, 2025

Would it pay to setup for overnight stays so you can sleep easy? In the event of a tornado warning for night time.

oldnslo · May 7, 2025

Do you have the option to put something in a side hill or is your ground flat? I have never built one but have seen several side hill dug out root cellars that double as storm shelters.

LittleBittyBigJohn · May 7, 2025

We are in tornado alley also. There were a couple of deadly tornadoes in 2011 and 2014 where I'm from. I have been fortunate enough that I was able to build a safe room into our house. It's above ground and easily accessible.

Typically shelters are used for a short time. I personally don't see the need for provisions or a toilet. Generally around here you watch the news or listen to the radio and if one is getting close you may go in the shelter for a few min to let that round pass. For light most people will either get by with a flash light or have solar landscaping lights nearby to just grab on the way down.

When you are thinking about location, remember you will likely be in a hurry, it will usually be dark, wet and raining. If it's too far you won't want to deal with the hassle and inconvenience of getting to it. That in mind a popular shelter that people install is flush mount in the floor of the garage. They are handy because you don't have to go out in the rain to get in them. But you have to make sure there is not a car parked to where you can't get in the door if you need to get in.

I noticed on your list you noted a "sturdy door". Please don't use a sturdy door. Use a Shelter door that is installed correctly. There was a family in a shelter that died because the sturdy door was ripped off the shelter and the family was sucked out by the tornado and were killed.

Ground water is just something you will have to deal with. Most are sealed pretty well at installation but will eventually either leak from the ground water seeping in or from rain coming in the door or vents. The installers will add a type of anchor strap that is designed to keep the unit from floating out of the ground if the water table gets too high.

gsganzer · May 7, 2025

I'm sure you can build one, but what's your time and money worth? I have a backhoe, so I dug my own hole to their specifications. They just drove up and dropped it in the hole. I think I paid $4000.

Mine is one of the sloped front concrete models, like this.

MossRoad · May 7, 2025

Just be sure you have a way of opening the door if something large falls on it. Like a very, very large hydraulic jack.

If you have an inward opening door, something heavy can put enough pressure on it so that the locking mechanism can get jammed. It doesn't take much.

If it's an outward opening door, that's self explanatory should something heavy fall over it.

My father built a bomb shelter in his basement back in the 50s (The Russians are gonna bomb us). It was all concrete with a concrete reinforced ceiling. It had a 4x8 wooden trap door that he eventually was going to replace with a cement slab door with dual hydraulic rams and a hand pump to open it but never did. It was large enough that you could go around a corner quite a ways and be out of the way if anything collapsed the trap door and stairs.

We spent many a time in that shelter during tornadoes. And when you're down in that hole, it's really quiet. And then the lights go out. And then every kid flicks on a flashlight and dad tells them all to save their batteries and we only use one at a time. Good memories.

Just be sure that if you go the underground route it has adequate drainage should you have a major flood event. Perhaps even a dike wall around the entrance should a flash flood come from a neighbor's property. And adequate ventilation.... that would be more than one source.

I'd just keep some comfortable seating or benches to rest on, a few gallons of water per person, some emergency blankets, and some flashlights with spare batteries. A radio would be nice if cell service died.

Good luck in your planning.

Blue Mule · May 7, 2025

Here in KY, underground shelters begin at about $5,000 INSTALLED and go up from there depending on how many people you want it to be able to hold. I doubt you can build your own for that price. So I would strongly suggest looking into a pre-fab and pre-engineered solution like so many companies offer these days. Also, there are some that they install under your garage floor. That way you don't have to run outside in the weather when the tornado warning is issued.

As far as the door goes, what people do around here is notify the local authorities that you have a storm shelter and they put you on a list. That way if there ever is a tornado they know to come look for you and if your shelter door is blocked rescuers outside will free you. To me the door would be a minor concern, as the companies selling these shelters have already done their homework.

drumminj · May 7, 2025

If you haven't seen it before, check out FEMA P-361 and P-320 documents on tornado shelter construction. It's focused on above-ground designs if I remember correctly, but does discuss necessary ventilation and such.

MossRoad · May 7, 2025

drumminj said:
If you haven't seen it before, check out FEMA P-361 and P-320 documents on tornado shelter construction. It's focused on above-ground designs if I remember correctly, but does discuss necessary ventilation and such.

Yep...