That is a whole lot of moisture for being empty for over 3 months. Are you 100 percent positive that you dont have a water leak somewhere, that has activated the urine smell. Is that an exterior wall, in the one picture that shows very wet? Have you gone over that entire floor with a black light, to identify, any other areas?

Hi cat_ky, the wall in the picture is an interior wall, right next to the stairs. Yes, there's no water leak, purely just pee. The seller has a large dog. Every floor board we took out is stinky and it even contaminated the trash can. We had three different contractors working in the house. Everyone was complaining and disgusted by the smell. That's why we ripped out the subfloor.

Yes, I scanned the whole area with a black light. For some reason, it doesn't work well on HW floor. It works on the wall. I had to sniff the floors...

Maybe something here that should help you. https://www.hunker.com/13423519/how-to-treat-subflooring-for-pet-odor-and-stains-before-installing-new-flooring

What is wrong with people? That poor dog. I hope you find a solution, but it's shocking that anyone would have to be dealing with this.

I had a customer, years ago, who owned a very nice home in a high end neighborhood (they rented after moving to a new home). The renters apparently only moved their dogs into the house and locked each of them into a bedroom, where they allowed/forced those poor dogs to use the hardwoods for their bathrooms. For months. The house was pretty much a tear down after that. Besides the floors the dogs had tried to dig their way out through the bedroom doors.

I know that doesn't help you, but I empathize with you having to deal with this.

While you have stuff opened up, rip out anything that was even remotely affected by the dog pee. Not removing everything will have you unhappy every time the weather changes and you can still detect a trace of the urine smell.

HI olychick, this is in the a higher-end neighborhood. We gave the seller 3-month closing and let them stay rent-free for 4 days post closing. I can't begin to explain various emotions as I deal with this. When I told my realtor about this, while she was empathetic, she said "well, it's a seller's market..."

Hi Chispa, I know what you mean, but stains are on the floor joists and the base plate for a structure wall. I can't remove and replace them.

“When I told my realtor about this, while she was empathetic, she said "well, it's a seller's market..."

isn’t there some kind of disclosure law that could help here. ? They lied t

Well that's another red flag for me - no houses that had pets in them! UGH. Thank goodness I am not planning on ever buying another home!

Look for dog urine enzyme cleaner to use on the areas you can't remove and then shellac after.

"We gave the seller 3-month closing and let them stay rent-free for 4 days post closing."

Wait --- do you mean that this dog urine damage happened during the 3-month closing and/or rent-free 4 day post-closing period of time?

Given the high moisture level, I would guess, yes, during the 3 month closing period

I was advised years ago to wash down with white vinegar to neutralize cat urine, worked a treat! You can only give it a try.....

Cat urine is completely different than dog urine. It's actually much worse! You can't even GET it out of a carpet. FAHGETABOUT IT. ;-)

"Given the high moisture level, I would guess, yes, during the 3 month closing period"

I would think that your real estate agent should have suggested this, but have you contacted a real estate attorney to inquire about suing the seller for the cost of all repairs? If you had a signed contract to purchase I would think the seller would have some sort of legal obligation to keep the property in the same, if not better, condition that it was in when you signed the purchase contract. To allow that much dog urine seems willful and deliberate. I'm really sorry you're going through this.