Cat Urine - How can I remove completely?

[Sarah W.]

I had a tenant who brought in 2 cats and an unapproved dog. Upon her move-out after a year, it appears that the cats and dogs were having turf wars. There was a HORRIBLE stench in the stair landing that has no windows. I took a black light to it and it just lit up the hallway with all of the streaking, dripping, and puddles. I had a contractor to come and remove the carpeting in the stairway and the entire downstairs. He said the whole back of the carpeting had urine stains and there was some dampness still on the subfloors in the stairway. DISGUSTING.

So, he applied Zorbit on the stairway overnight and the next day, he applied 2 coats of

oil-based kilz original. It helped a lot but did not get rid of the smell completely. You can still smell it in the air. Next step, we plan to apply a coat of the Zinsser Bin on the staircase and walls in the staircase, hoping that will get rid of it.  Then use a deodorizer in the paint to help freshen up the smell, and open the windows to flush it out.

I have no idea what else to do to eliminate the odor. Any other ideas?? Get the air ducts cleaned or use an ozone treatment? I am hoping the shellac primer works, but worried because the smell is so pervasive. 

[Sarah W.]

To follow up, here's what I did. I thought this was smell was never going to go away!

I believe some of the residual smell was coming from the stair seams not being caulked up yet AND we discovered there was another big spot at the hallway near the stairs that were stained . So, my contractor did the following:

1. Blacklighted all carpeted areas, stairways, walls, baseboards to find spots 
2. Removed all carpeting, treated the subflooring with enzymatic cleanser.
3. Caulked all openings, seams.
4. Applied BIN (which worked way better than Kilz original) to walls, baseboards, and stairs.
5. Repainted everything and used an air deodorizer in the paint.
6. Ozone treatment to shock all the smell out. Worked AMAZINGLY!! It went from this nasty cat smell to clean fresh smelling air. We aired it out all day and overnight to get the ozone treatment cleared, but it really did the trick after all these steps.

Tenants came in and said they stood outside the door, saying "Here we go again..." with the smell, but were surprisingly pleased that there was no smell!