I've got high spots that appear to be poor subfloor prep. In investigating those spots I've discovered the section that slopes down in both directions from a steel beam. The hardwood floor runs perpendicular to the beam and parallel to the joists.
I'm still trying to understand how to apply the "less then 1/8" in 6' or less then 3/16" in 10'" spec. My GC is reluctant to address the issue and is interpreting the spec different then I believe it should be.
This is an excerpt from the National Wood Flooring Association guideline:1. For installations using mechanical fasteners of 1 1/2” and longer, the subfloor should be flat to within ¼” in 10 feet or 3/16” in 6 feet.
2. For glue-down installations and installations using mechanical fasteners of less than 1 1/2”, the subfloor should be flat to within 3/16” in 10 feet or 1/8” in 6 feet.
Do you want to check it? Get a long (6 foot) level or a shorter level and a straight board. Put one end on a high spot, rotate the level and check the gap from the bottom of the level to the surface of the floor. If any of the gaps are greater than the tolerance for the distance ( 6 or 10 feet) and fastener length then it is out of spec. It's probably not totally accurate to do this on the finished floor as some of the boards may not conform to the subfloor. But if boards were installed parallel to the joists the low spots may be more pronounced.
Do the high spots seem to be on the joists with valleys between the joists?
GC can blame whoever he wants i.e. flooring guy or framer but they work for him. Did the inspector give you a written report?