When we purchased the house, the existing floors were an assortment of carpet, laminate, bamboo, concrete and natural, original stone. The natural stone, which resembles slate with the metallic properties of Mica or Pyrite, was still present in the entry way and around the fireplace. Thankfully, we were able to keep the awesome, original stone but everything else was too worn or out of date to salvage.
For the living floor, landings and master bedroom area, we chose a walnut engineered hardwood. When the installers came to preview the space, they warned that they might have issues which would prevent theem from being able to install the hardwood due to the intolerence level of the subfloors. Since most older lake front homes, including ours, have sloping and/or uneven floors, they anticipated such isses.
The day of the hardwood installation, they were only able to install three rows of the 5″ planks before the unlevel floors caused them to bow and flex so much they began to crack. At this point, they would not continue installing the flooring and gave us two options: 1) carpet everything or 2) level the floors.
After weighing the options, we decided to have them level the floors in the living, bedroom floors and entryway. They first appllied liquid cement to level the uneven areas and then applied 1/2 plywood on top of that. In some areas, the correction was as much as 3″.