As I understand it, that is currently illegal. I used to own a rental house with a retired couple for tenants. They had a bed in the basement for visitors. On one county inspection, the guy said the be had to go because there was an interior door between the area with the bed and the outside, walk-up door to the back yard. So, several compartments in a basement sounds dodgy at least and dangerous at worst.
I believe there is a move afoot in the county to loosen the accessory apartment regulation that would allow more occupancy in what were single-family houses. I'm sure that's driven by the results of the county's sanctuary policies.
Montgomery County is a great place...to get away from.
