TheKeith wrote:

actually those aren't exactly surface roots--tehy dug their backyard deeper
which is what exposed that big root (it used to be completely buried). I
don't think they should have touched the tree at all, particularly not a
major supportive root, which by the way, they want to completely eliminate.I
posted the pictures more to show the situation than the damage that already
occurred which it's obvious is worse than the pics convey, since a certified
arborist referred to the current damage as severe.

Could be far worse. Can you bypass graft the notch with branches
cut from the same tree?