DO NOT buy a SFR unless you have an approved accessory apartment attached that's livable.  

I recommend not adding those kinds of accessories in rentals.

Also you can look for SFR's that have an accessory apartment.  

Your agent can very easily get you the information in accessory dwelling units.

You can rent out accessory units to your primary residence (a carriage house, an attic apartment, etc), but you can't rent out the other side of a duplex.

It is possible with accessory unit but not part of the main structure.The planning department will not approve your plans.3ft set back is grandfathered and anything new will need to have 5ft.Some cities will allow you to match the 3ft setback.

If the factory isn't using, 5/16 or 3/4 inch plywood or at least CDX, 2x6 exterior wall construction, double pained tinted and rated windows, porcelain fixtures, granite or marble countertops, stainless steel fixtures, copper plumbing and upscale accessories they don't and will never git my biz. 

Consider Airbnb, renting by the room, creating a duplex in multi family zoned pockets, or creating an accessory dwelling unit if that is allowed.

I'm looking for information regarding existing companies that specialize in Accessory Dwelling Units in the Southern California area.

Hi DC BPers,I purchased a SFH in Deanwood with the intent of converting the basement into a legally permitted, separately metered accessory apartment.