foundation elevation problems on new build

huangyhg

foundation elevation problems on new build
i have bought a residential new build and the foundation poured does not match the footprint for my house.  the house comes with the option of converting the three car garage to a two car garage with library in place of the third bay space.  i selected the library option but they shaped the foundation elevation as if it was going to be a three car garage and now the elevation in the third bay is not even with the rest of the "living space."  it is a post tention slab and i am not sure what the appropriate and acceptable corrections are for this mistake.  what options do the engineer and superintendent have?  i'm worried they'll just pour another layer of concrete on to fill in the elevation difference and am worried about the lack of bonding between the two pours. the elevation difference slopes from 3" in the front of the garage and blends in at the back of the garage.  i have too many questions and this post is already long enough.  hope it makes sense. -thanks
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you did not say what part of the country you are in.  if you have a post-tensioned slab you must have expansive soils.  you need to find a structural engineer that can look at the plans and the as-built condition.  the engineer you select should know something about prestressed concrete.  anything else is guess work.
i know it's going to be tough, but you're never going to have more leverage with the builder than you do now.  i' assuming this because you haven't paid him for the whole amount yet.  i'd make him tear out the post tensioned slab and do it right.  you're going to be living with his work for a long time.