Removing Particle Board Flooring

I purchased a home built in the late sixties, and the kitchen floor left much to the imagination. I have recently removed 1 layer of vinyl flooring and 1/4" of particle board to find the original floor tiles and another layer of 3/4" particle board. This layer of particle board crumbles and you can actually dig it up with a spoon - if needed. The floor rises and dips in areas (around the fridge and sink), which I know is from the particle board aging - no water damage seen. Would it be my best interest to pull up that layer of particle board, are there any precautions that should be taken not to damage the subfloor, or should I patch the bad areas, seal and lay down 1/4" marine plywood. Any suggestions are greatly appreciated - It's not easy on your own again.

 

Particle board is not considered to be an appropriate substrate material for any type of floor covering. It tends to be found in older homes under carpet. Remove the particle board and install plywood subfloor.