How much value does addding a second unit to a home add?

[Mark Lynch]

I know it would be hard to give me a solid number. But, can anyone on here give a round about amount you could expect to add on to homes appraised value if you add a complete second unit to a home. Let’s say a 2 bed 1 bath loft style unit.

I have home I have access too that is off market. It has a 2 bed 1 bath upstairs unit that is in great shape just needs cosmetic updates. Below it is a 2 bay garage with a separate office and bathroom. The downstairs already has its own separate electric service and meter. My idea was to make a second unit in the downstairs. I could get this place for substantially lower then appraised value. Older owner looking to unload.

I know every area you is going to have dinner deferent home values. But, is there some type of formula I could use to get close. Say, adding a second unit would add 30k, 50k to the homes value??

Any help would be appreciated!