ClarkKent

I just wanted to check... You seem like a great person, as does everyone here, but I am new to this site and needed to make for my own sanity if for no other reason.
There ARE some real weirdo's out there as I'm sure you know. It sounds like we are going to be great friends !
I'm so excited for you.
Go for it!

Hey Clark?...

I just wanted to say one more thing here on the subject and then I'll leave your to your madness.
There is a HUGE amount of responsibility that comes with a room like this.
You will be tempted to do things down there that just should not be done.
Please, do not lose yourself and the good person that I know you are.
Just don't do it if you feel the temptation will be too much to handle.

You understand what I'm sayin here sweetie?

You could always go with the overseas container idea, and forgo all that BS. Just coat it really well with hot tar before you bury it.
This, you can do by yourself with a rented machine (excavator).
Just make sure you put a garage or something on top of it.

Happy building....

During the construction phase of the basement, make sure you are ready to answer any questions that might arise from inquisitive minds. Create an reason you are doing it this way and stick to your story. I would make sure it makes sense too.

When you are ready, cut into the dead space, and break out the concrete saw.
I suggest that you keep the size of your secret entrance to a minimum. Just big enough to get what you are going to need down there and that is it. The smaller the space it takes up the less noticeable it will be, and the harder it will be to find. Most importantly, be creative in hiding it.

Good luck.

Make sure you allow room for all this to sit on with a shelf designed into the wall structure, and allow the wall to continue up until it will be flush with your finished sand floor. Everything should fall inside this wall structure except the finished concrete slab, which will be poured by a different crew of Mexicans (very important). You must act as your own Contractor throughout this entire build so study up.

Let the framing crew get to work on the architecturally approved blue prints (this will not show a basement), which there will be a record of in the county records office, and make sure there is a closet sized dead space over your future entrance. Let the all the other Sub-contractors finish and move into your new home.

Now you need to think about the entrance. I would use brick and mortar to frame out the entrance, 3 courses high, right on top of the steel.
Once this is done, cover the whole thing (just the corrugated steel) with about 6 - 8" of sand and pack it down with a vibrator (this will prevent settling latter on), including the newly formed entrance, so the whole thing is nice and leveled off with the top course of your bricked entrance. Lay down a moisture barrier (plastic sheet) and roll out your wire re-enforcement. Pour concrete over the entire floor 6" thick (which now forms the roof of your secret room), let it cure and apply a sealer.

If new is where you are going then you are defiantly on the right track.
What ever you do, DON'T place it outside of the floor plan. It will show up like a Roman candle under an infrared scan from the air.
Next: Do you have a trusted friend that knows how to run heavy equipment, or do you think you can handle it yourself? If so, then draw your own plans and dig it out. Pour the footing yourself. Then (this is very important) hire some Mexicans to put up the walls. I would suggest pouring solid formed walls all at once as this will make the entire structure water-proof (you still need to do the parching on the outside though).
Then on your own with a little casual labor, put up the support trusses for the floor w/lolly-column supports, and place corrugated steel for a sub-structure. Don't worry about any entrance yet, but keep in mind as you lay out your floor trusses.

Ooooh... I'm sorry about that... It kept telling me there was an error.

I hope I'm doing this right?
So, you want to build a secret room? No problemo...
The trick is not so much the room itself as making the entrance secret.
If you have a basement that is not noticeable from the outside of the house, YOU'RE IN BUSINESS !!!

I hope I'm doing this right?

Nope.

No problemo...

Thanks for the rep. That photoshopped pic of her in a Superwoman costume is super