the root system of a wild tree will generally match the branches/twigs to sustain the foliage... and the root system can still be contained in a smaller volume soil if water nourishment is sufficient.
Either way, even on the ground floor, Miker777 will need to contain and control the root system. Little water will seep through under the house, and the roots must be prevented from interfering with the foundation, sewerage etc. not to mention the pool in the next room. Even so, it is true, that an elevated atrium would need a quite large "flower-pot" to sustain a ceiling height tree..
Entirely agree with you. Either way, even on the ground floor, Miker777 will need to contain and control the root system. Little water will seep through under the house, and the roots must be prevented from interfering with the foundation, sewerage etc. not to mention the pool in the next room. Even so, it is true, that an elevated atrium would need a quite large "flower-pot" to sustain a ceiling height tree..
But I think not to an extent where it would be impossible.
And I didn't speak about the weight of the raised structure (foundations, ground, structure, ...). 
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SH3D 7.1 and nothing else - W11 64b in 4K
