building underground home.whats involved?

Research it online. Seriously?

This isn't a shelter forum and the answer to your question could take hundreds of pages that have already been written with diagrams, photos, arrows and smiley faces.

Why do you have Internet access and not use it for it's fundamental purpose... the sharing of information?

Start here: https://www.google.com/search?q=oscilloscope+input...

in case you reside in a community that has a intense water table, then residing underground in a leaky basement is tough. maximum homes equipped in those factors do no longer actually have a basement or a hurricane cellar, because of the fact preserving an underground room dry is complicated, if no longer impossible. moist basements breed mildew, illness, and at last rot and crumple. ===edit== the possibilities of any particular domicile (which includes yours) being the only that is definitely hit by skill of the twister is so small, that it is not nicely easily worth the rate to construct underground. maximum folk needless to say take their possibilities.

2-3 inches thick is absurd - you don't need as much as 1/2" The dirt covering supports the walls.

Gravel floor is absurd - concrete merely to give a level surface and possibly to enclose pipes and electrical conduit.

You don't put it in a spot where water accumulates, you put gravel underneath to encourage drainage.

Sewage is a major problem as it is gravity flow in most places.

Underground homes are fairly common these days for energy savings- read up online about choices