Are american sycamore roots a problem for foundations or pipes?

Big, vigorous and shallow near the surface, exactly as you would expect from a floodplain species, and the standard guidance is to keep it well away from walks, drives and foundations. Note that the setback advice is often misunderstood: roots cannot crack a sound sewer lateral, they only exploit joints that are already failing, so the honest reason not to plant one over a line is that you do not want to remove a mature sycamore the day that line needs excavating.