ALWAYS, ALWAYS, ALWAYS get a Survey!!!
We are now working to get the property line moved and the adjoining owner is being very cooperative. There is however no assurance that the adjoining owners in other cases will be as helpful. In fact, if the house (or more commonly a driveway) is over the property line it can be a 5 figure expense to make things right. Just like any other form of insurance, you don't really need a survey until you need it and then you REALLY need it. Because we live in the mountains here in the Gatlinburg area, placing a house isn't as simple as it is on flat land and builders do make mistakes (as proven via the link above). Take my advice, get a survey, and we'll both sleep better!