Most home projects involving any major changes to the structure of your home will require a building permit. These permits are required for your safety and that of your neighbors. If you don’t obtain a permit when one is required, you could be facing major fees down the road. Building and construction permits vary greatly based on the city or county you live in. Check with your municipality’s building and permit office to know which permits are required for your remodeling project. In general, permits are required for these bathroom remodel situations:
Changing the structure of your home. This includes demolishing/removing walls, changing the use of a room (like changing a closet into a bathroom), or additions.
Creating new holes in your house (for new windows, doors, or vents/fans).
Moving plumbing or wiring (even just moving an electrical outlet).
Adding a water heater.