Two Houses-One Lot. What should we be concerned about?

[Sara Smith]

We are looking at purchasing a property with both a 3/2 "main" house and a 2/1 ADU in the back. Originally built as mother-in-law quarters. Separate driveways for both. Main house has a garage, ADU doesn't. ADU does have laundry. Called the city and they said it was "legal but non-conforming" and that permitting major renos could be a problem in the future and if one burned down we couldn't rebuild what would be a second living unit. But no issues with renting it to two separate parties. Anything else I need to check or be concerned with? It's one address. Dividing mail and trash? My guess is we'll have to pay utilities because we won't know how to split them. Thanks!