Five bills made effective on January 1, 2020 have significantly streamlined the ADU construction and approval process.Plus: The budget agreement (enacted June 27th 2023) restores $50 million for the California Housing Finance Agency’s ADU Grant Program, which provides up to $40,000 to help cover the planning and permitting costs involved in an accessory dwelling unit.- BP thread relating to your question: https://www.biggerpockets.com/...- LA County has multiple different cities with different RSOs, so this will really depend.

We currently are under contract to buy a .3 acre lot in downtown that is in a frequent transit area, which means we are allowed to build two accessory dwelling units on the lot. we are also zoned for a duplex, so that’s the plan!

If your configuration is such that you have 2 couples and a single occupant in your converted triplex, you may be conforming to a duplex use.Another thing to explore is an accessory unit.  

@Nikki Closser similar story: we recently closed on our first investment property three days before closing on our new primary residence lol :-) We also relocated, sold our house in Los Angeles - which we had rented out with Airbnb and had built an Accessory Dwelling Unit in the backyard, and moved to Columbus Ohio.

I explain that on my condo, house and accessory dwelling unit alone here in Los Angeles will net approximately $100,000/year with 3% appreciation in 30 years.   

You will have to go out and visit your properties even if you have good management and those costs can really take a chunk out of your cashflow when it's just a property or two.Yes Denver is tough right now, but you might consider another condo (maybe turn your current one into a full rental and do another owner occupied loan to keep your out of pocket costs down) A house with an accessory unit that you could rent out might be practical.

 Arlington County should soon allow accessory cottage type building to be built in the backyard ..  

This is the most cost effective option.You can go the Accessory Dwelling Unit (ADU) or the Accessory Family Suite (AFS) route.ADU/AFS are two similar routes that require you pulling the permit for one of these designations and getting inspections along the way.

Seattle does have a Accessory Dwelling Unit rules; however, it requires that the property owner live in one of the units. 

ADUs are easier to permit, but they result in an accessory unit (not an SFR).