Build a garage with apartments on top?

[Mark Devens]

Hello all! I'm planning on building a garage on my personal property and had this idea: I need two stalls for myself which is doable, but what if I expand to 4 stalls, add 2 apartments above with 1 bedroom each or maybe make them studios, each tenant gets a stall, and rent is $600 per unit. Based on rough estimates of cost to build the entire structure, the $1200 per month pays off the whole thing in about 6 years after my own down payment and then can pay for the mortgage on the existing house. Anyone have experience with this? Good or bad idea? Do cities usually have a problem with this or no? I've done searches but haven't found much. Thanks for any advice and have a great day!