I would like to widen existing ground floor garage in a two-family house further into basement/utility area. Ground floor is not connected to either of the apartments above, there are stairs outside of the house. At the moment it’s 6 inch slope over 44 feet of garage depth. Would it be legal to level the garage floor with basement floor?
Seriously though sounds like you would want to contact a concrete contractor. They would know more about this.
Like Simon said contact your building department to discuss your plan.