I am a new member on this site and have a question about particleboard basement subflooring.
I have removed the vinyl floor to find that the previous owner used particleboard as the subfloor in our basement. The joints are sealed well and it appears to be dry on the surface, although I have not checked the underlining of the subfloor. I plan to install long laminate flooring, likely 3/8'' click type maple and was wondering if I should replace the particle board with 5/8'' plywood, or could I nail down 3/8'' plywood on top of the particle board. Also, what is the best way to determine if the particle board is damp underneath, short of ripping it up.
Tricks of the trade or suggestions would be greatly appreciated!

Is this on top of concrete? If so, it must come up before installing another floor over it. P. board is terrible over concrete. In time, it turns to dust. If you desire a long term installation, best to remove the P.board.

Thanks for your advice Gary.
Funny thing is about this press wood or particle board is that it has been there I believe since 1975. And yes, the cement floor is under a 2 x 4 frame with 12 or 16 on centres. Also it doesn't give and yet 2 contractors have said, you have gone this far, tear it out! Decisions, decisions!