What Size Building Requires a Building Permit

Do I need a building permit for a building under 500 sq. ft. with power or sewer in the County?

If the building is going to be habitable, you must have a room/area for cooking, bath and sleeping.  A floor of finished material and power and heating must be installed and yes, you would be required to pull a permit.  If the building is not habitable, i.e., for storage, a garage, cart port or workshop, you do not need a permit.  However, if there is any electrical involved for the non habitable room, a permit would be required for the electrical work, or if the room will be  heated and cooled, a permit would be required for the heating and cooling work.