The automatic timetabling of complete schools is still a challenging task. We employ the allocation and scheduling framework evAlloc, which is generating solutions by means of an evolutionary search engine, for a timetabling application in an Austrian secondary school. Amongst common constraints like assigning specific courses to specific rooms, or considering time preferences of teachers, the requirements for this application include even more complex constraints. In specific subjects school classes are split into groups with students of similar performance, hence, a single class requires a number of rooms. The real-world data utilized for development and experiments are provided by a secondary school in the Tyrol, where the final application will also be tested and evaluated in daily operation by the school's administration.