Are your cats annoying you by spraying in the house? Are you framing spraying rules for your cats which are not being followed by them? Well, all of these might cause you to break you head wondering how to stop cats from spraying in the house. But, you need to have some patience in order to stop cats from spraying in the house.
You may not succeed in stopping cats from spraying in the house, but you can alter their behavior in such a way that you make them spray only at certain places in the house. This is actually a far better way of how to stop cats from spraying in the house than trying to make them go out of the house just for spraying. You can actually train the cats to use the bathroom for spraying. Even better, you can build a small bathroom just for the cats and train them to use that bathroom.
Cats are usually not subtle when they spray. The smell of the urine will reach you wherever you are in the house. Smell of ammonia would be similar to the smell of ammonia. Cats would spray wherever they feel like. If you are not able to alter the spraying behavior of the cats, then you can try your luck by hiring a cat specialist.