urinating everywhere

Question
I have a 4 1/2 year old black lab, he came from a pet store at approx 2.5 months. He does not seem to understand not to use the washroom on the floor. I bring him outside all the time (at least once an hour) to use the washroom, sometimes within mins of coming inside he will pee all over the floor. I tell him NO sternly and then he starts peeing! I'm at my witts end, he is not abused or  nor has he been abused, if i speak to him sternly he starts peeing everywhere. He will never ask for the door, the only time he whines to go the the bathroom is if he is in his crate. I need help!!! I'm sick of walking in pee!

Answer
This will be very difficult to straighten out.  It is a well entrenched habit.  At his age, he must make a lake.  This is going to take a lot of attention on your part.  He sleeps in the crate and keeps it dry?  Take him out the first thing in the morning.  Walk him around, letting him stop to sniff.  When he goes, praise him.  Really go on about what a good dog he is.  Keep an eye on him constantly inside.  Close door or put up gates to keep him in the same room as you.  Some people even leash the dog to them.  Watch for the usual sniffing behavior, and take him out when you see him.  Again, walk him around letting him stop to sniff, and praise him if he goes.  When he gets up from a nap is a good time too.  Continue the scolding when you catch him in the act, and take him out.  

You might go ahead and have the carpeting cleaned or rent a steamer.  This will make it harder to find a good place inside.  As he establishes new ''good places'' pay extra attention when he is near them, and be quick to take him out.  Also praise him and take him out when he get near the door.  I am not sure it is obvious to dogs that if they go to the door, you will let them out. You are not going to fix this in a few days.  Keep at it.