SDR, running utilities to your ADU could either be fairly simple or double the project cost, if your current setup is too small to be simply extended to the ADU.
I asked a developer about preserving my house and building a triplex behind it versus just tearing it down for 4 units. He said completely new hookups are needed and building around an existing one is extremely expensive and kills the economic advantage of building 3 instead of 4 units.
