How to Replace My Home's Subfloor

Remove the main floor in large pieces so you can easily reconstruct it, if possible.

Tear away the subfloor using a crowbar. If the subfloor is heavily damaged, then this should be a relatively easy process.

Rip away from the damaged parts any parts of the particleboard or plywood. The flat pry bar and cat's paw will come in handy for this task.

Use a circular saw with a carbon-tipped blade to cut out pieces of the floor if the plywood continues beneath a wall. Next, cut the plywood along the center of a joist. Alternately, cut next to the already existing floor joist in a place devoid of nails. Put a 2 by 4 on the joist's side. This will present your saw from going through any nails.

Replace damaged floor joists. Whenever possible, cut away the damaged part of the joist and add splices to the sides to save money. You can use reciprocal saw for this activity.

Remove loose nails from the floor joists. Get ready to put new plywood down. You will likely need to accomplish this by blocking with 2 by 4s. Secure the 2 by 4s you use down with the help of galvanized framing nails. Paint trouble spots with creosote.

Cut the pieces of plywood. Put them in place. You can substitute particleboard for plywood, if they are of the same thickness. The plywood should be just as thick as the former subfloor.