Hi,
My son is also 12, he autistic, but recently started urinating on the floor also. He knows the behavior is wrong and is punished by having to shamppo the floors, also losing privelgdges of using the room we discovered the "puddle", along with no tv, no pc, no movies. He knows the behavior is wrong, and will repeatedly say only pee in the bathroom, but he doesn't seem to be able to stop himself.
At first I thought it might be a "confusion" of senses since he recently hit puberty, but I'm beginning to think it might be more of an OCD behavior (he tends to preseverate on things anyway), I'm starting to think we might have to have him evaluated for a low dose medication to see if that helps this very unwanted behavior.
Good Luck, this is an incredibly frustrating one, and we've went through a lot of behaviors in the past 12 years. lol
I wonder if there are any problems in the household in general. You isolate this habit, but give no other information. His behavior is so outrageous that there must be moe to it.
He is 12 year old and should know better so this a time when you tell him this is unclean and unwelcome behavior, No TV NO PC , nothing hs likes to do until the behavior stops, make him scrub the rugs ....