Double Height Basement Dig Outs : How ???

[rideforever]

I saw this documentary about double height 5 star basements being dug out in flash Kensington houses, sometimes 2 floors like this, and I wondered how the hell this is possible ?

Please don't tell me they jack up the ceiling and get a spade out ?

How can they do it without 4 floors of house coming crashing down on their heads ?

And how can they extend the foundation slab etc... going down ???

I would be interested if someone can help ?

Thanks

 

[KenGMac]

I suppose it would be possible to sheet pile front and rear elevations? but what about the two "party Walls??"

Or Boring in a Diaphragm wall may work??

But drawback of both is the vibration that will affect the property being worked on and the two adjacent multi-million £££ residences, plus there is the minor factor of what is holding up the external and internal cross walls of the property being worked on.

Must admit, my immediate thoughts about this type of "Adaptation" is to avoid it like the plague

 

[John D v2.0]

Presumably just keep digging out and underpinning until you're down as low as you need. Not rocket science, more like heavy work.

 

[rideforever]

In one documentary they talked about techniques that are used on skyscrapers, so I think sheet piling is more likely.