My dog started peeing the the house, why?

I have three dogs, two cats and a chinchilla. A few months back I noticed my dog started peeing in the house. At first I thought it was a medical problem, I took him to the vet and found nothing wrong with him. Okay so the dog is mad. I can't figure out why he is doing this. I started giving him more TLC. He usaully only does when my husband is not home. Nothing new my husband has always worked. It shouldn't be because of the other pets they all been together for a few years now. I let him out all the time. He will pee if I am gone 3 mintues. He use to be a really good dog, he use to wake us up in the middle of the night if he had to go. He goes outside as much as he needs to. I can let him out and go drop the kids off at school and he would pee. Right now he spend most his time in the back room with a comfy bed and goes outside till my husband gets home. We already had to pull up all the carpet and get a new sofa because he would pee and pee all over the,. I can't afford to keep replacing the sofa. We got tile floor for easy clean with all the pets now. Anybody have any ideas why he is doing this? Any ideas what i should try to break him of this bad habit? I am also worried that my other dogs will pick up this habit, will they? thx for any help.

[Jaybay]

First, you need to take him back to the vet for a urinalysis and some basic lab work.  If he had the beginnings of a urinary tract infection months ago, it wouldn't necessarily have shown up back then.  

If the problem is completely behavioral, you'll need to take a good long look at what his life is like.  Now that he's contained in a cell most of the time, the problem will only get worse.  Dogs go nuts when their activities are severely curtailed.

If he doesn't go on daily walks off the property, that's the first thing you need to commit to doing.  Dogs are genetically wired due to the remnants of wolf DNA to travel for food ever day.  If you work with mother nature and satisfy that need, you'll be surprised how many other bad behaviors fall away.  Ideally you'll want to walk him twice a day - in the morning and in the evening for at least 30 minutes.  The routine is walk, eat, rest.  

What is a typical day like for him now as compared to before the peeing problem?