cigarrettes and cat pee
Quite a few years ago my wife and I rented a house with the same problem. We spent a month and hundreds of dollars cleaning and painting along with everything else we could think of to get rid of a cat urine problem. It turned out we could not do it and we never moved in.
If you do find a good solution to this problem please return and post it so others will know. Cat urine is one of the most difficult odors there is to get rid of.
I'm assuming the cat urine soaked into the hardwood floors. In that case I don't think sanding and refinishing would help. Does anyone else have suggestions on that? Maybe the sanding and putting a couple coats of polyurethane on it would help.
Anyway, there IS a solution to your problem. Bleach and Polyurethane. I got the industrial strength Clorox available at Home Depot. This stuff kills everything from TB to HIV so I figured it would do for cat pee! I put on several applications of the bleech over a 2 day period. Beware, the bleech reacts with something in the cat pee and makes sort of a toxic cloud..lol. Seriously...wear a mask.
After that, and this is the KEY step, I applied two good coats of the polyurethane. Poly will lock in anything..smoke, odors, etc.
In your case you would want to bleech, stain then poly. I'm not sure how the wood will look after you bleech it compared to the rest of the floor but a few good coats of stain should get it looking right. In my case it was just a plywood floor and I recovered with carpet.
In any case, that solved my problem 100%. Even on hot, humid days there is no odor.
NATURES MIRICLE is an enzyme based solution SPECIFICALLY for CAT URINE. Using bleach of anykind will just cause a chemical reaction with the amonia that is in the urine. There are "crystals" in the urine that harbor the smell. Bleach alone WILL NOT get rid of them. You can find the nature's miracle @ PETCO. Spray on the urine areas and really soak the wood. Cover with wet towels then plastic. You want to keep the area wet and warm. You should notice a difference within 24-48 hours.
Our situation was a little extreme - I had never experienced anything like it. We definitly had to remove ALL the flooring, but someone who might have a small problem area can hopefully benefit from our experience.