Brooklyn, NY Basement Conversion Project

[Inemesit C.]

I'm looking for insight to a current project we are working on as I haven't been able to fins much info on it. We are looking to purchase a one family house that is reasonably below market value. The basement is above grade but currently incomplete with a height of only 6'5ft. We are looking to excavate down to bring the height to 7.5ft which would then in turn allow us to change the C of O to a two family and rent the basement out as a unit. We have an architect that proposed underpinning the basement. As we are looking for the most cost efficient way to complete this project, we have also spoken to numerous contractors that stated, first we would need to see where the foundation is below the property by completing borings tests. The contractors are stating that underpinning is not required if we do not need to excavate past the foundation. If there is at least 2-3 ft of soil below the current slab and the foundation, we would only need to excavate, place new insulation and gravel then a new slab. Is there anyone that has faced a situation similar to this or have any insight to this type of project?