Does anyone know of effective barriers to a new floor to keep kitty kats away?

https://www.urinegone.com/

this product really does work. it comes w/ a little black light to find the smell and then it's chemical removes all the bio enzymes that create the smell. After treating you then use the black light again and make sure it's gone. I only needed to use it once in my home. My sister bought a house and the old owners let their dogs defecate and urinate on the side porch w/ wood and carpet and we needed to use Urine Gone twice to eliminate the smell. That house was nasty, but Urine Gone did work finally to cure the problem. her hubby also had allergies to the dogs and this product finally solved the problem left by the old owners. Try it for $20 you might just save yourself having to sand and refinish.

You're going to need to make sure you get the smell completely out of the wood before refinishing it... or you'll simply be covering the odor so that humans don't smell it, but the cats will.

Are the cats spayed and neutered? If not, you need to do that first or they'll simply mark their turf again.

Urine Gone does a good job of getting rid of odor.