We have removed old tile in preparation for new ceramic tile in our front entry way. Once the tile was broken up and removed, we discovered particle board underneath. We tried to bring this up, but it has been set on the plywood underneath with mortar! Any tips or tricks for how we can get this up? New plywood has been laid everywhere else to reinforce the subfloor, and the plan is to put down Ditra, however there is not enough room to put plywood or Ditra down on top of the particle board at the front door where the tile was as the height would then be level with or above the door jamb.