Adding a basement bathroom to your home has a lot of benefits. You'll be adding value to your home - houses with more than one bathroom have a real advantage, even in slow markets - and you'll be increasing livable area and convenience. The basement is the best place to add a new bathroom to just about any home. After all, it's less costly than expanding the existing house, and easier than sacrificing upstairs living space for another bath. However, before you jump into this project, there…