Foundation underpinning problem

Hi,
Half of our basement was dug down about 6 inches more than 30 years ago. I just pulled down some wall panelling in the dug-out section, and discovered that there is about a 4 inch gap between the bottom of the foundation wall and the basement floor. I can clearly see earth fills this gap.
Here are a couple of photos of the gap:
http://jjlloyd.googlepages.com/basement
The house was built in the 1920s, and the foundation is poured concrete. The basement floor is poured concrete. The earth is very sandy, and we do not have a problem with water via the gap. There are no cracks in the foundation wall, nor are there cracks in the exterior brick of the house to suggest bad settling. I have only uncovered a small section of the walls so far.
I've had a couple of contractors in who suggest an expensive "proper" addition of footings. Another contractor suggested the earth be dug out several inches past the exterior of the foundation wall, and back-filled with concrete to make a sort of 1/2 footing. Or I was considering just filling in a few inches of concrete on the inside to prevent the earth from spilling inwards. But I don't believe that will add any structural support.
Do I really need expensive several-feet deep footings with weeping tile, etc., to replace the earth that hasn't moved much in all this time?
Any opinions are appreciated.
Thanks, Jeff
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You certainly do have an unusual situation. Normal basement walls would be sitting on a footing, hopefully with a French drain system on the outside of damp proofed basement walls. It does not appear that this is what you have.
Perhaps you could do 4' sections at a time. Work out a detail that would accommodate your interior finish and allow you to excavate and pour sections of footing in a leap frog fashion. I am thinking you could perform this work and pour on the inside. Plasticizer and/or expansive concrete with a vibrator would insure good bearing for the walls. You would finally end up with a footing and dirt seal that extended below your present floor. The cold joints between pours will be natural avenues for water and I see no good way to waterproof the exterior other than excavation, but water has apparently no been a problem to date. I am surprised you do not have any symptoms and I do somewhat agree that if you have not had a problem, why worry now.
___________________________ Keep the whole world singing. . . . DanG

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I say if it ain't broke, don't fix it. many old houses don't have footings and are fine. footings are often overkill (not that I'd ever build a house without footings) it all depends on the bearing capacity of the soil, and yours must be fine. what would be the gain of adding footings? to prevent settling and cracking? but if it hasn't settled yet, why would it start now?
Don't go adding a second story or something like that though.
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