Wood – How smooth should I expect final finish to be on an new hardwood floor install

Here is a link here for the kit and instructions on its use, if you feel this may do it. Depending on where the damage is, once touched up, furniture placement or rugs may do the rest which I would not recommend, but it is a shortcut instead of the alternative.

The alternative is selective plank replacement. I have seen this done in a few different ways, brute force with chop axe and hammer, more delicate but the same with chisel and hammer which I have done a lot of repairs myself with a chisel. My preferred way now is to use a set to depth circular saw to cut the middle of the plank length wise with 2 cuts about a 1/2" apart. This will keep the blade away from nails or staples that hold the floor. Of course, do not cut into the adjacent pieces, unless they need replacement too. Then with a sharp, wide chisel, say 1-2" wide, split the ends the rest of the way to the neighboring planks. when making this cut, angle the chisel so the crack is wider at the top from both directions so the center piece is easier to remove. There will be a tongue and groove joint to deal with on the ends, so with a smaller sharp chisel cut the center rip in the middle to allow to draw the tongue and groove apart from the adjacent planks. This 1/2" rip from the middle when cut in the middle and lifted out will provide a good "handle to grab to remove the center. Once that is done the groove side of the damaged plank is easy to remove. The tongue side take a little finesse and a dull chisel.

To reinstall the new section, remove the bottom half of the tongue. You will most likely need to cut it to length also. Slip the new piece in and nail the back edge where the modified groove is and use a colored wood filler to fill the set nails.

You could apply a few coats of a water-based clear finish to the floor. This you can apply with a roller and it dries fast so you can probably do two or three coats in as many days. Then later, if you choose to to a more complete job, you will fix the sag and then re-sand the entire floor and apply finish again. This would only cost you the price of the can of finish and a paint roller.