Looking to buy a duplex and convert large garage into studio

[Mario F.]

Hello, I'm looking into buying a duplex in Los Angeles.  My offer has been accepted but I'm still debating whether to take it.  This duplex has two small units and a large spacious lot in the back along with a three car garage. I was thinking about converting that garage into an extra studio/lounge space for myself while using the extra empty space on the lot for a carport.  Would this be illegal?  I could rent the space to an artist or just use it for my own studio since the apartment is so small.  What do you guys think?  

Thanks

mario