What is an ADU and is it legal in Johns Island now?

ADU means accessory dwelling unit, a smaller second home with its own kitchen, bathroom, and entrance sharing a lot with the primary house. Whether one is currently allowed on a Johns Island lot depends on that property's specific zoning district and utility capacity, since rules can differ from one part of the island to another. Brian Beatty can confirm the current zoning designation for a specific Johns Island address before you plan one.