How to make a basement unit legal in chicago?

[Michael D Valadez]

I bought and rehabbed a 2-flat in chicago this year and now I'm turning my attention to the basement. It was a legal 3-flat but the last owner had it decoverted to storage a year before the sale. I was told there was a plumbing problem in the basement and a clean out had to be installed.

When the last owner had it converted to storage, the took out the bathroom/kitchen plumbing and electrical. They even poured concrete in the toilet and shower drain. 

Where do I start to get it back to a legal 3?

[Bruce Woodruff]

I googled it and it said something about 2500 SF of lot size per unit...I didn't read it all though, go check it out