Hello,  

I purchased a legal 3 flat in Chicago (RS-3 currently zoned) that that we are gut rehabbing and are looking to convert the basement into a 4th unit.  We will have 2 means of e-gress, proper ceiling height (7ft. 6in), 1,500 sq. ft per unit, etc. for the basement.  I've heard different answers when it comes to adding this 4th unit and the main 2 are below:

1)  I should hire an attorney and need to re-zone the property to add the 4th unit.

2)  I can do this on my own and we do not need to change the current RS-3 zoning (if it was RS-1 or RS-2 that would not be possible) and I should reach out to the alderman to find details to have property changed from a 3-unit to a 4-unit. 

I would like to do make this a legal 4 flat as it will help tremendously with the ARV and allow me to get 80% of the money back out of this BRRRR.

My initial thought was to go to the alderman and speak with him regarding the project and our desire for the 4th unit. 

If anyone has done this or knows the process I would greatly appreciate any advice.

Thank you,

Tim