Hardwood is a preferable flooring solution for many houses. It keeps the home warmer and away from noise between the floors. Very often, such floors had big problems with 'weaker' floorboards, and they usually have to be changed over the years. We did a complete restoration by reclaiming about 10 floorboards, sanding the entire surface, and gap-filling to fill all the holes. The final thing was the finishing, which we did with clear lacquer.
The job took 3 days.