Yesterday, the Raleigh City Council approved an ordinance that allows any detached house or duplex to add a second, smaller, "accessory" dwelling unit with its own kitchen and entrance. It can be in a separate building (e.g., a backyard cottage or above a detached garage), an addition to the existing house, or within the same house; it can be rented separately, even as a short-term rental or as a live/work. Any construction still has to comply with the usual UDO regulations, notably setbacks, and do note that this change to the UDO does not go into force immediately.

As has been pointed out here before, the Raleigh area has a very limited selection of multifamily properties. The housing stock in Wake County is heavily tilted towards single-family properties, and now this law means that those can legally become 2-unit properties. It's easier to rent out a fully separate, legal apartment than to rent out a room/suite within a house.

You can read the original ordinance text and background from the Raleigh City Council agenda, but per IndyWeek, the ordinance as passed does not include items 3, 6, or 7 under "D. Accessory Dwelling Unit Regulations."

Raleigh now joins Durham, Charlotte, and even Cary, which has long allowed one "utility dwelling unit" within the same structure.

ADUs have long been popular on the West Coast, so there's already lots of people here on BP who know about them:

https://www.biggerpockets.com/blog/accessory-dwelling-units-tips
https://www.biggerpockets.com/blog/accessory-dwelling-unit-cash-flow