Almost 5 yr Old is Urinating in Room

[Momof2boys1girl]

I have an almost 5 yr old little boy. He is very smart, and uses that to his advantage. I have caught him, 3 times now urinating on his bedroom floor. Then when he is caught, he has blammed it on his younger brother or the dog. I dont know what has brought this on, and I had no clue how to address the situation. I told him, this was unexceptable and it wouldnt be tolerated. And My husband and I took some things away from him. Lately he has been very snotty and rude to us. Mostly myself, when my husband is at work. In the past we have been known to buy something when we go to the store, even after a fit. It was like we were rewarding it. We have stopped and made stricker grounds. So I dont know if he is rebelling on that or what. I will place him in his room in time out, and I will address the situation when he calms down. But seems that no matter what I do, the punishment isnt strong enough and he doesnt take it as a threat, nor does he take it seriously. Please if anyone, has exp this type of behavior give us some adivce! We have a one yr old and another one come in a few months. We dont want this to affect the other children.