Just around the corner from where I live in Tennessee is a little colony of houses that sit directly on the water in a quiet cove off the Tennessee River. These are 'regular' homes with dining rooms, bedrooms and baths. Unlike a house boat, these homes have no motorized power and cannot be used for travel. But, you can store your boat in your floating house garage. Each house floats atop large blocks of foam. Two long steel arms anchor each house to land and allow each home to rise and fall with the level of the river. Each house also has its own gangway for access to land.
These homes are registered annually with the state's fish and game department, just like any boat or jetski. Permits are no longer being issued for new development of these types of homes.
I wish I knew someone who owned one, I'd love to take a peak inside any of them. I'm sure there are some funny stories from people who own them, imagine getting drunk and loosing your footing and going for an unexpected dip.