'Nearly' high-rise timber buildings in Germany - Project, experiences and further development

Since 2008 a number of 'nearly' high-rise multi-storey timber projects in Germany were realised up to eight storeys. As they are 'outside' of building regulations, exceptions in the area of fire regulations were necessary. To enable approvals and to avoid non-controllable cavity fires, massive timber (CLT, Glulam) or massive-timber/concrete hybrid constructions were chosen. Staircases are built in concrete, which requires special investigations to limit the vertical deformation of the timber structure. Facades are made out of a mineral-wool based ETIC, in other cases timber claddings are applied. New projects will use also massive-timber staircase and elevator shaft. Experience demonstrates that the structural and fire design is a minor problem, but moisture safety requires more alertness. For wider application further development of regulations and improvement of economic solutions are necessary.