I used Odorxit on a plywood subfloor. There was definitely cat and dog urine from previous owner, but later I realized that some of the wetness was a plumbing leak. So I can’t say for sure that it was the Odorxit, the plumbing fix, or the carpet removal that solved the problem, but I never smelled the pet urine again.

I've used Odorxit also, on a concrete floor. The process they called for was not simple, but it worked like a charm. Worth a try IMO.

We used Nature's Miracle for the dog urine residue in our current home. The previous occupants left the carpet in and had 5 dogs, two of which never went outside. Couple that with leaks in the basement windows and completely full gutters, the basement was a HUGE mess. Hazmat gear to remove carpet/pad and three gallons of Nature's Miracle and zero odor---and no biological hazard since the product chemically changes the urine/etc.

For a plywood floor, just apply enough to leave the surface wet and let dry. On our upstairs(hardboard over subfloor), we used a string mop to literally slosh on the product and let dry for two days.

Then installed hard maple flooring over 15# builders felt underlayment and rosin paper.

Almost ten years later, still zero odor/etc. problems.

I hope you got it for a good price. Odor is the biggest thing that will stop someone from buying a house. Good luck!

I sealed my old subfloor with layers of paint I picked up for next to nothing that were mixed wrong from paint stores and second hand remideling stores. Just pour the paint onto the floor and push around to cover. Repeat a few times to completely seal the subfloor. Last expensive way I found to fix my issue.