Particleboard is a pressed material used during the 70’s and 80’s as a filler or shim beneath carpet. It can still be seen used in shelving or modular furniture. Because it is brittle, it is not a suitable substrate for nails or cleats which are used to install solid lumber. Before installing new solid lumber, the particle board must be removed. Oftentimes it was install over 1/2” plywood which, by modern standards, is too thin. In some cases 1/4” OSB may be added for additional support but it not always appropriate. Our quotes assume no underlayment exists unless specified in the bid. If specified that MHW is removing it, price assumes underlayment or floor is nailed down and not glued. If glued down, removal may not be possible and a floating might be a better option.