I am installing 3/4 inch oak throughout my first floor. The install is over the original pine, which sits directly on the joists. I put 1/4 OSB over the pine (due to a number of factors 5/8" wasn't practical).
I removed a tile hearth pad where there used to be a fireplace. That left me with a roughly 2 ft x 5 ft concrete patch that I had to deal with. I placed 1/4 hardiebacker concrete board to get it roughly even with the floor and then patching compound to level it out. There is also 1/4 OSB over the patch area, which I secured with concrete screws. The long side of the patch runs perpendicular to the floor boards against a wall.
What is the least-bad way of securing the hardwood over that patch? I'm a relative newbie to this, so any insights are very much appreciated!