But how it got that way matters not. How to fix it matters alot.
Dan began by removing the hardwood floor and pulling ALL the nails stuck in the subfloor. Then came a layer of plywood.
We were beginning to think it was possessed. A little more build up was required with more leveler.
My tile guy agreed to put one final coat of leveler down around the edges to feather everything as smooth as possible.
Whatever dips and bumps showed up after that dried would have to smoothed out with adhesive.
Finally it was deemed level!