Help! I have recently bought a old house that has hand hewn oak beams and joists and I have several rooms that need to have the floors leveled.THe unlevel floors are due to the beams beams & Joists being milled by hand and also settling of the house. The house was renovated & remodeled prior to my buying it, and the builder did not address the floors properly. One room is downstairs and 3 are upstair bedrooms. All have a plywood subfloor and are currently covered with carpet. Due to the weight of concrete self levelers,I have thought that shims and another layer of plywood would be better. How do I go about doing that to ensure it is leveled properly.