Just had new engineered hardwood floor put into my renovated basement and the floor is very uneven in places and is sometimes even squeaky. Do I need to rip it up and redo?

What did they put under it ?

There is a thin blue foamy underlay, don't know the brand name.

There are also spots where you can actually feel the dip (feels like the floor will break soon) so I'm assuming there was no evening poxy poured before. The contractor says it's a "floating floor"... I do NOT believe him!

A "floating floor" does not mean it is in middle air. It refers to type of installation(not nailed or glued down).

The blue foam is to aid with the movement for expanding and contracting.

To releave the up and down movement, floor would have to be removed and substrait straight edged.

Have contractor come back and correct it.

Chuck