Adding a new bathroom can certainly add to your home in many ways from comfort to added value to your home.
Some things need to be considered when thinking about adding a bathroom in your home:
Location of the new bathroom—You will need to consider the layout of your home and where the existing plumbing is located.
Is there a crawlspace or basement in the home—having either of things may give you more leeway in determining the location of your bathroom as it might mean that plumbing and wiring can go mostly under the house instead of in the walls.
What is your budget—the further you have to run plumbing away from existing plumbing or cut into slabs, the higher your budget will need to be if you are adding a new bathroom.
When considering a new bathroom, or even a remodel of an existing one, consult your plumber before beginning the project to get professional advice on the plumbing work that will be required to complete your project.