Illinois Roofing Exam Prep offers two training classes to prepare you for the state roofing exam. The residential (limited) class is a two day class and the commercial/industrial (unlimited) is one additional day (three days total). The class material is condensed into manageable increments to explain everything you need to know and nothing you don't. The class schedule, built around the average work day and designed for the working contractor, meets from 5 P.M. – 9 P.M.