Block Knoten (block node). A versatile spaceframe system using machined solid nodes and precise welded beams from hollow sections. Profiles are normally rectangular but can be round. High strength corrosion resistant fasteners are hidden and require prestressing into the node using special Novum wrenches. Beam ends are comprised of plates or blocks which are inserted into the tube and can be either recessed or protruded for welding. The beams allow direct attachment of varied cladding systems.

BK tubes are used in single layer and double layer spaceframe applications and are the preferred choice where geometries are close to orthogonal to keep nodes compact. Typical applications are cones, domes and vaults. Single layer applications use the BK node and for double layer grids the HK node (half spherical) integrates BK tubes with KK tubes creating bending stiff chord members on stiff spatial grids.