Yesterday my brother decided to pull up a piece of the particle board in the living room, (which is a converted carport/garage) and found this underneath. The plan is to install laminate flooring over the entire floor including the stairs. Don't worry, I only have 3 steps down. My question is would I necessarily need to install a piece of thick moisture resistant plywood on top of this before laying the laminate or can I get by with something not quite as expensive or thick as 3/4 inch plywood, but just as durable and acceptable for putting down the laminate flooring? These planks run all the way over the room. Actually I fully expected to see just 2x4s laid flat underneath the particle board on top of the concrete, but not the case. It looks like cedar planks to me, but I could be wrong.