On 2 January 2006 the roof of the ice rink in Bad Reichenhall collapsed. Fifteen people died, twelve of them children and young people. In September 2006 the conference of state building ministers adopted guidance on checking the structural safety of buildings. The engineering guideline VDI 6200 grew out of it and appeared in February 2010. It covers buildings of all kinds except transport structures. It requires operators to keep a building logbook, and certified experts must carry out the inspections. Each building is placed in a class according to the consequences its failure would have.