Wife and I just purchased a home and moved in on the 23rd of December. We noticed a stank coming from the ac vents but choked it up to a stagnet unoccupied home in Florida. Boy were we wrong! We traced the smell to the entry way closet where the previous owners stored a very neglected litter box (Gross!! by the front door?). The cats urinated all over the dry wall, carpet, padding, to the concrete and into the 2x4 wall supports. Unfortunately that closet shares a cavity with my HVAC plenum and intake. So when we turn the AC on it circulates throughout the house. I have stripped and cleaned the area, took out a foot of drywall, and removed the urine soaked insulation. The smell is still in the concrete and 2x4s. I have used enzymes, and tried vinegar with baking soda already and it hasn't worked. I need industrial sized help so please do not tell me to use vinegar or enzymes.