What is the span of the joist, 16" of 24"? that right there makes a big difference.

16"

Sounds like your subflooring is too thin. Is it OSB? Have never been happy with just OSB subflooring. Might check to find out what is the thickness of the subfloor and check that against local codes and your flooring installation specs.

I believe my subfloor is 5/8" thick. Also, what is OSB subflooring?

Thanks for your help

John

Right there is your problem. OSB or Oriented Strand board is garbage wood glued and pressed together to make a smooth strong sheet of plywood. Problem is when it gets wet it tends to expand. The problem your having is due to the fact they used 5/8" instead of 3/4". 5/8" is good if your using it on top of an existing subfloor, but tends to bounce when used by itself on anything greater than 12" OC.

No, it is not normal to be able to tell when you are standing on a joist or between joists, ESPECIALLY in a new construction house. ACD is also correct that 5/8 is not enough for a subfloor by itself.