I installed the nail down engineered hardwood downstairs and did an OK job as far as leveling the subfloor is concerned. I sanded a few high spots down and even used a planer on an especially stubborn spot.
I'm now moving on to the upstairs and I am weary of the same situation. Is there anything else I can do to ensure the subfloor is level?
What are leveling compounds? Are they worth it -or- more of a mess?