Assuring quality is of central importance for the companies of the HDH. Apart from optimising production processes, the focus is also on the safety of the products and customer satisfaction. The Federal Quality Association of Industrialised Building and Off-Site Housing (Bundes-Gütegemeinschaft Montagebau und Fertighäuser e.V. - BMF) concerns itself with this topic by monitoring and certifying off-site housing manufacturers, saw works, metal plate fastener truss producers and steelwork fabricators. As a RAL quality association it is authorised to award the RAL quality symbol "Wood house building", "Steel system building" and "Mobile Space Systems" to its members. Following notification through the Deutsche Institut für Bautechnik, the CE marking can be awarded for the production of metal plate fastener trusses and construction kits for buildings made of wood as well as the grading of cut wood. According to the German Federal State Building Codes (Landesbauordnungen) the off-site housing manufacturers are also monitored, and may then attach the conformity symbol required by planning and building laws to their preassembled wood panel elements.