Thought this might be useful to anyone who like my friend bought a house where previous owner was old lady with way too many cats. Carpets were chucked out but house still smelled in fact it honked. They tried numerous sprays that were supposed to use enzymes and other neutralizing agents and nothing worked. The smell was just masked. So in a kill or cure effort I suggested using pool PH reducer (from my chemical kit from kids above ground splash paddly pool) can be bought online and in diy stores.Upstairs was floor boards and downstairs was concrete slab. We mixed up warm water in mop bucket (half full) and added approx half a cup of reducer. Opened the windows and mopped the floors. As we were doing it the smell was going. It took about 5 mins to do each bedroom. Then we did down stairs. Just as fast. All windows were open to provide ventilation. The floors were left to dry. Smell has totally gone with no real effort. Floors have now been mopped with nice smelling household cleaner. We then went outside where the fake grass was also stinking. Mixed the reducer up in a watering can and it worked there too.They had spent a fortune at pet shop buying loads of products and they just didn't work. So if anyone else has the same problem this could save you time money and effort.