Basement apartments are problematic from a fire code perspective, especially if it's a "true" ADU that doesn't connect into the main house.
Re:I hate living in my tiny house
by alistairSH on Monday October 07, 2019 @08:47AM
(#21180102)
Correct. The basement ADUs I've seen in this area are on partially exposed "walk out" basements, so there's a dedicated door and window(s) for egress. Most retain a door to the main area, just dead-bolted (so no use in a fire).
Similarly, most towns and counties are subdivided such that tiny plots aren’t available.
There is a growing movement to allow ADUs in urban spaces, but it’s far from universal. If memory serves, Arlington VA (next to DC) allows an ADU within the main house (converted basement) with some fairly strict limits. No ADU in the back yard.