Do you Duplex?

[Jennie Testman]

Hi all!!

I'm in need of some advice. I'm looking to purchase my first property as a live-in flip/upgrade. I found a property that is a 4 bed 2 bath, an addition was made without permits to make a 2 separate 2 bed 1 bath units. If I purchase this property could I make it into a legitimate duplex if the property is zoned for it? 

What would be the benefits of making it a legal duplex as opposed to just keeping it as is and renting out the other unit as is. Would the value of the property go up with as a legal duplex? How would I even go about making it legal?

The property is in San Mateo County... Please help!

Thanks!