In-Law Suite/ADU Laws in the DMV?

[Joseph Ayoub]

Hey all, I'm looking for my next house hack in the DMV and since inventory has been pretty low, I'm considering adding an in-law suite or ADU to a potential property. My question is does anyone have experience doing this in the metro DC area (PG County, Montgomery County, Washington, D.C. Alexandria, Arlington, or Fairfax County) and if so, can you tell me about your experience? Specifically, I want to know what the process looks like, the legalities behind it, zoning considerations, etc. I want to make sure that if I add an in-law suite or ADU it is legal and if I move out, the property will still be legally rentable. So depending on the ease/information, it will help me narrow my search to a more specific market.