It can be done...but you may find that it is more trouble than it is worth. The main problem I see is that the new flooring material may not match the tone of the "same" hardwood, and the thickness might not be precisely the same. If it weren't prefinished, it could all be sanded and finished and then it would likely all look the same, but, as it is, you might find it looks like you patched it in. In addition, the new material will look a little shinier than the existing. It's admirable that you want to reuse this material rather than trash it, but you may not like the result.

We did just what you are proposing and it turned out very nicely. Our entire house was 1918 hardwood and when we reconfigured a room, we saved the original hardwood and used it in the hallway. We also have some extra that we're going to use as a staircase landing when we refinish our attic.

This isn't, however, a DIY job. You'll need a hardwood flooring guy who knows what he/she is doing.

As mentioned above it is possible but you'll probably end up paying more in labor to have it removed without damage than if you just trash & replace it.

Assuming say $6/sq ft for the materials @ 20 sq ft is $120.

Also, that material will most likely not match as closely as you'd like to the new material it will be installed with. And I doubt you want to sand & refinish the new material so that it matches up w/ the other 20 sq ft.

I agree; it's just not worth jumping through hoops for such a small amount of flooring.

If you aren't going to reuse it, please at least try to remove it and donate to someone who will like Habitat for Humanity's Reuse stores or a salvage company or something. Although it *does* grow on trees, it's a valuable resource not deserving a dumpster. When I remodeled my kitchen and DR and added about 30 sq ft to my dining room, I went out and bought vintage hardwood in the same dimensions as my existing floor. The hardwood guys did an amazing job of incorporating it into the floor (the whole thing was sanded and refinished after installation.)

I did exactly this in my DIY kitchen remodel. The wall between the kitchen and the dining room was moved 2 feet into the dining room space, and I removed the 3/4" oak flooring in that area. Also down at the end of the kitchen where there is now an opening between the kitchen and the dining room, the space where the wall used to be needed to have some flooring, and I felt it would be better to cover that section with oak, rather than the tile that I was going to put in the kitchen, so that the wood floor/tile floor transition aligned with the corner of the angled peninsula.

It was fairly easy to reinstall a few of the old floor boards in that space, although I used stainless steel torx-drive trim head screws angled through the grooves, rather that putting the special L-shaped nails through the toungues.

Since the floor was originally site-finished, the new boards are not perfectly even with each other, but unless you look closely and run you hand over it, you can't tell.