Need help with tornado shelter idea.

[bryanj58]

Here in the south we do not have basements. My garage is 4.5 ft lower then my house. I was thinking about cutting out a section of center block and excavating (by hand) under the house for a tornado shelter. I would like to get a 10w x 10l x 7h room.

My question is how do I safely support the concrete floor so that it does not fall on me while I

[Matt In Oklahoma]

First check your water table and make sure you wont drown while doing it. Then I would look at the way old mines are done and the cartels use tunnels with wood bracing and good plywood. make sure you stay away from load bearing walls and supports so you dont ruin the foundation. Your insurance may not support this decision of going under the foundation either.

[SeldomSeenSlim]

Honestly, and I'm not trying to be a jerk here, but I think this is an area where if you have to ask then you should probably not try it yourself. It's certainly doable, but it is a huge undertaking with a lot of risk.

[barfife]

As opposed to digging under your slab, consider building a small concrete building (either poured walls and roof or concrete block walls with rebar and filled with concrete and pored roof) with a steel door. Make it look like a tranditional backyard storage building. It would work as well without the inherit dangers of digging under your slab. Just a thought.

[tech]

Some excellent replies...a garage 4.5 feet below a house here is called a swimming pool.

Seriously, an excavation as large as you are hoping for is going to require additional footers (below grade) and support pilings to even think about being safe. The small concrete bldg would be better, especially if earth was graded up to (or over) the roof level to divert high winds.

[barfife]

The small concrete bldg would be better, especially if earth was graded up to (or over) the roof level to divert high winds.

I worked for Barnett Bank in Florida when hurricane Andrew came through. I had a bank in a community that was completely flattened, nothing but slabs left! The only structure more than 6 inches tall remaining was our bank vault. The rest of the bank was gone but the vault remained.

[NewHampshireLady]

Its probably to late for this to be of help but.....my relatives live in Georgia and they built a tornado shelter by buying a new concrete sewage tank kept the top in place and the installed some solid stairs, door and then built a small shed over it. Its close, its been used twice and has kept the family safe.