Underpinning-Lowering basement will benefit your family or your pocket! Increase your living space or make it in to revenue by finishing the space as basement apartment.
In a case like this picture above you will have to underpinn the neighbour foundation wall as well.
Ideally your house should be at least 20″ from your neighbour.
First example shows the houses at 1′-0″ from each other-in which case it’s impossible to do the traditional underpinning.
You can either do a bench system or get a Structural Engineer to design the underpinning to withstand the pressure from the adjoint foundation wall.
This example shows the benching system. In this case you would have to bench the foundation wall or when a party wall agreement has not been reached
This example shows an optimal situation where a traditional underpinning can be excecuted and achieved an aprox. 8′-0″ ceiling (assuming neigbours ceiling heigth is approx. 6′-5″)
This example is the best case scenario when you’ll have a min 2′-0″ or more distance from foundations
In this case you’ll need a party wall agreement in order to underpinn.
Oterwise a bench system is required.
Some times we have a situation where an existing crawl space is found and most of the times you will have to dig 3′-0″ or more down to achieve the desired height