The City of Chicago provides homeowners with the "tools" one needs to build a porch or deck that meets the requirements of the Chicago Building Code. Based on whether one has a building that is one unit wide or two units wide, and whether your building is frame construction or masonry construction, you will be able to determine which of the following configurations of porch or deck you will be able to construct. 

Check out the City's Guide to Porch Design and Construction.